Summary of the AWS Service Event in the Northern Virginia (US-East-1) Region

https://aws.amazon.com/message/12721/

by eigen-vector • 5 years ago

638 384 5 years ago

aws.amazon.com

Exceeded character limit on the title so I couldn't include this detail there, but this is the post-mortem of the event on December 7 2021.

Fordec3• 5 years ago

Between this and Log4j, I'm just glad it's Friday.

eigen-vector2• 5 years ago

Unfortunately, patching vulns can't be put off for Monday.

_jal• 5 years ago

You are clearly not involved in patching.

Fordec3• 5 years ago

Simply already patched. Company sizes and number of attack surfaces vary. 22 hours is plenty of time for an input string filter on a centrally controlled endpoint and a dependency increment with the right CI pipeline.

JCM93• 5 years ago

Obviously one hopes these things don’t happen, but that’s an impressive and transparent write up that came out quickly.

markranallo• 5 years ago

Its not transparent at all. A massive amount of services were hard down for hours like SNS and were never acknowledged on the status page or in this write-up. This honestly reads like they don't truly understand the scope of things effected.

nijave7• 5 years ago

It sounded like the entire management plane was down and potentially part of the "data" plane too (management being config and data being get/put/poll to stateful resources)

I saw in the Reddit thread someone mentioned all services that auth to other services on the backend were effected (not sure how truthful it is but that certainly made sense)

jtchang• 5 years ago

The complexity that AWS has to deal with is astounding. Sure having your main production network and a management network is common. But making sure all of it scales and doesn't bring down the other is what I think they are dealing with here.

It must have been crazy hard to troubleshoot when you are flying blind because all your monitoring is unresponsive. Clearly more isolation with clearly delineated information exchange points are needed.

dijit4• 5 years ago

“But AWS has more operations staff than I would ever hope to hire” — a common mantra when talking about using the cloud overall.

I’m not saying I fully disagree. But consolidation of the worlds hosting necessitates a very complicated platform and these things will happen, either due to that complexity, failures that can’t be foreseen or good old fashioned Sod’s law.

I know AWS marketing wants you to believe it’s all magic and rainbows, but it’s still computers.

beoberha• 5 years ago

I work for one of the Big 3 cloud providers and it’s always interesting when giving RCAs to customers. The vast majority of our incidents are due to bugs in the “magic” components that allow us to operate at such a massive scale.

mperham• 5 years ago

I wish it contained actual detail and wasn’t couched in generalities.

nijave7• 5 years ago

That was my take. Seems like boilerplate you could report for almost any incident. Last year's Kinesis outage and the S3 outage some years ago had some decent detail

propter_hoc2• 5 years ago

Does anyone know how often an AZ experiences an issue as compared to an entire region? AWS sells the redundancy of AZs pretty heavily, but it seems like a lot of the issues that happen end up being region-wide. I'm struggling to understand whether I should be replicating our service across regions or whether the AZ redundancy within a region is sufficient.

dijit4• 5 years ago

The main issue tends to be a lot of AWS internal components tend to be in us-east-1; it’s also the oldest zone.

So when failures happen in that region (and they happen more commonly than others due to age, scale, complexity) then they can be globally impacting.

propter_hoc2• 5 years ago

I agree with you, but my services are actually in Canada (Central). There's only one region in Canada, so I don't really have an alternative. AWS justifies it by saying there are three AZs (distinct data centres) within Canada (Central), but I get scared when I see these region-wide issues. If the AZs were really distinct, you wouldn't really have region-wide issues.

randmeerkat• 5 years ago

AWS has been getting a pass on their stability issues in us-east-1 for years now because it’s their “oldest” zone. Maybe they should invest in fixing it instead of inventing new services to sell.

AUX4R6829DR82• 5 years ago

The stuff that's exclusively hosted in us-east-1 is, to my knowledge, mostly things that maintain global uniqueness. CloudFront distributions, Route53, S3 bucket names, IAM roles and similar- i.e. singular control planes. Other than that, regions are about as isolated as it gets, except for specific features on top.

Availability zones are supposed to be another fault boundary, and things are generally pretty solid, but every so often problems spill over when they shouldn't.

The general impression I get is that us-east-1's issues tend to stem from it being singularly huge.

(Source: Work at AWS.)

nemothekid2• 5 years ago

I've been naively setting up our distributed databases in separate AZs for a couple years now, paying, sometimes, thousands of dollars per month in data replication bandwidth egress fees. As far as I can remember I've never never seen an AZ go down, and the only region that has gone down has been us-east-1.

cyounkins3• 5 years ago

Is that separate AZs within the same region, or AZs across regions? I didn't think there were any bandwidth fees between AZs in the same region.

treis• 5 years ago

AZs definitely go down. It's usually due to a physical reason like fire or power issues.

maximilianroos• 5 years ago

I've never never seen an AZ go down, and the only region that has gone down has been us-east-1.

Doesn't the region going down mean that _all_ its AZs have gone down? Or is my mental model of this incorrect?

wjossey6• 5 years ago

There was an AZ outage in Oregon a couple months back. You should definitely go multi AZ without hesitation for production workloads for systems that should be highly available. You can easily lose a system permanently in a single AZ setup if it’s not ephemeral.

banana_giraffe3• 5 years ago

It can be a bit hard to know, since the AZ identifiers are randomized per account, so if you think you have problems in us-west-1a, I can't check on my side. You can get the AZ ID out of your account to de-randomize things, so we can compare notes, but people rarely bother, for whatever reason.

lanstin2• 5 years ago

If you do a lot of VPC Endpoints to clients/thirdparties, you learn the AZIDs or you go to all AZIDs in a region by default.

mnordhoff• 5 years ago

Amazon seems to have stopped randomizing them in newer regions. Another reason to move to us-east-2. ;-)

codeduck2• 5 years ago

the eu-central-1 datacenter fire earlier this year was purportedly just 1AZ, but it took down the entire region to all intents and purposes.

Our SOP is to cut over to a second region the moment we see any AZ-level shenanigans. We've been burned too often.

ashtonkem2• 5 years ago

The best bang for your buck isn’t deploying into multiple AZs, but relocating everything into almost any other region than us-east-1.

My system is latency and downtime tolerant, but I’m thinking I should move all my Kafka processing over to us-west-2

nijave7• 5 years ago

Over two years I think we'd see about 2-3 AZ issues but only once I would consider it an outage.

Usually there would be high network error rates which were usually enough to make RDS Postgres fail over if it was in the impacted AZ

The only real "outage" was DNS having extremely high error rates in a single us-east-1 AZ to the point most things there were barely working

Lack of instance capacity, especially spot, especially for the NVMe types was common of CI (it used ASGs for builder nodes). It'd be pretty common for a single AZ to run out of spot instance types--especially the NVMe ([a-z]#d types)

pinche_gazpacho• 5 years ago

Yeah, cloudwatch APIs went to the drain. Good for them for publishing this at least.

iwallace• 5 years ago

My company uses AWS. We had significant degradation for many of their APIs for over six hours, having a substantive impact on our business. The entire time their outage board was solid green. We were in touch with their support people and knew it was bad but were under NDA not to discuss it with anyone.

Of course problems and outages are going to happen, but saying they have five nines (99.999) uptime as measured by their "green board" is meaningless. During the event they were late and reluctant to report it and its significance. My point is that they are wrongly incentivized to keep the board green at all costs.

amalter• 5 years ago

I mean, not to defend them too strongly, but literally half of this post mortem is addressing the failure of the Service Dashboard. You can take it on bad faith, but they own up to the dashboard being completely useless during the incident.

dijit4• 5 years ago

Once is a mistake.

Twice is a coincidence.

Three times is a pattern.

But this… This is every time.

s_dev• 5 years ago

You can take it on bad faith

It's smart politics -- I don't blame them but I don't trust the dashboard either. There's established patterns now of the AWS dashboard being useless.

If I want to check if Amazon is down I'm checking Twitter and HN. Not bad faith -- no faith.

luhn• 5 years ago

Off the top of my head, this is the third time they've had a major outage where they've been unable to properly update the status page. First we had the S3 outage, where the yellow and red icons were hosted in S3 and unable to be accessed. Second we had the Kinesis outage, which snowballed into a Cognito outage, so they were unable to login into the status page CMS. Now this.

They "own up to it" in their postmortems, but after multiple failures they're still unwilling to implement the obvious solution and what is widely regarded as best practice: host the status page on a different platform.

tw042• 5 years ago

Multiple AWS employees have acknowledged it takes VP approval to change the status color of the dashboard. That is absurd and it tells you everything you need to know. The status page isn't about accurate information, it's about plausible deniability and keeping AWS out of the news cycle.

discodave9• 5 years ago

The AWS summary says: "As the impact to services during this event all stemmed from a single root cause, we opted to provide updates via a global banner on the Service Health Dashboard, which we have since learned makes it difficult for some customers to find information about this issue"

This seems like bad faith to me based on my experience when I worked for AWS. As they repeated many times at Re:Invent last week, they've been doing this for 15+ years. I distinctly remember seeing banners like "Don't update the dashboard without approval from <importantSVP>" on various service team runbooks. They tried not to say it out loud, but there was very much a top-down mandate for service teams to make the dashboard "look green" by:

1. Actually improving availability (this one is fair).

2. Using the "Green-I" icon rather than the blue, orange, or red icons whenever possible.

3. They built out the "Personal Health Dashboard" so they can post about many issues in there, without having to acknowledge it publicly.

ProAm• 5 years ago

You can take it on bad faith, but they own up to the dashboard being completely useless during the incident.

Let's not act like this is the first time this has happened. It's bad faith that they do not change when their promise is they hire the best to handle infrastructure so you don't have to. It's clearly not the case. Between this and billing I we can easily lay blame and acknowledge lies.

nwallin• 5 years ago

So -- ctrl-f "Dash" only produces four results and it's hidden away in the bottom of the page. It's false to claim that even 20% of the post mortem is addressing the failure of the dashboard.

The problem is that the dashboard requires VP approval to be updated. Which is broken. The dashboard should be automatic. The dashboard should update before even a single member of the AWS team knows there's something wrong.

Clubber• 5 years ago

Yes, it's a conflict of interest. They have a guarantee on uptime and they decide what their actual uptime is. There's a lot of that now. Most insurances comes to mind.

notimetorelax2• 5 years ago

If you were deployed in 2 regions would it alleviate the impact?

ransom1538• 5 years ago

Yes. Exactly. Pay double. That is what all the blogs say. But no, when a region goes down everything is hosed. Give it a shot! Next time an entire region is down try out your apis or give AWS support a call.

hvgk2• 5 years ago

No. We don't have an active deployment in that region at all. It killed our build pipeline as ECR was down globally so we had nowhere to push images. Also there was a massive risk as our target environments are EKS so any node failures or scaling events had nowhere to pull images from while ECR was down.

Edit: not to mention APIGW and Cloudwatch APIs were down too.

multipassnetwrk• 5 years ago

Depends. If your failover to another region required changing DNS and your DNS was using Route 53, you would have problems.

electroly4• 5 years ago

The entire time their outage board was solid green

Unless you're talking about some board other than the Service Health Dashboard, this isn't true. They dropped EC2 down to degraded pretty early on. I bemusedly noted in our corporate Slack that every time I refreshed the SHD, another service was listed as degraded. Then they added the giant banner at the top. Their slight delay in updating the SHD at the beginning of the outage is mentioned in the article. It was absolutely not all green for the duration of the outage.

logical_proof• 5 years ago

That is not true. There was hours before they started annotating any kind of service issues. Maybe from when you noticed there was a problem it appeared to be quick, but the board remained green for a large portion of the outtage.

JPKab• 5 years ago

Multiple services I use were totally skunked, and none were ever anything but green.

Sagemaker, for example, was down all day. I was dead in the water on a modeling project that required GPUs. It relied on EC2, but nobody there even thought to update the status? WTF. This is clearly executives incentivized to let a bug persist. This is because the bug is actually a feature for misleading customers and maximizing profits.

ALittleLight2• 5 years ago

I worked at Amazon. While my boss was on vacation I took over for him in the "Launch readiness" meeting for our team's component of our project. Basically, you go to this meeting with the big decision makers and business people once a week and tell them what your status is on deliverables. You are supposed to sum up your status as "Green/Yellow/Red" and then write (or update last week's document) to explain your status.

My boss had not given me any special directions here so I assumed I was supposed to do this honestly. I set our status as "Red" and then listed out what were, I felt, quite compelling reasons to think we were Red. The gist of it was that our velocity was negative. More work items were getting created and assigned to us than we closed, and we still had high priority items open from previous dates. There was zero chance, in my estimation, that we would meet our deadlines, so I called us Red.

This did not go over well. Everyone at the Launch Readiness meeting got mad at me for declaring Red. Our VP scolded me in front of the entire meeting and lectured me about how I could not unilaterally declare our team red. Her logic was, if our team was Red, that meant the entire project was Red, and I was in no position to make that call. Other managers at the meeting got mad at me too because they felt my call made them look bad. For the rest of my manager's absence I had to first check in with a different manager and show him my Launch Readiness status and get him to approve my update before I was allowed to show it to the rest of the group.

For the rest of the time that I went to Launch Readiness I was forbidden from declaring Red regardless of what our metrics said. Our team was Yellow or Green, period.

Naturally, we wound up being over a year late on the deadlines, because, despite what they compelled us to say in those meetings, we weren't actually getting the needed work done. Constant "schedule slips" and adjustments. Endless wasted time in meetings trying to rework schedules that would instantly get blown up again. Hugely frustrating. Still slightly bitter about it.

Anyway, I guess all this is to say that it doesn't surprise me that Amazon is bad about declaring Red, Yellow, or Green in other places too. Probably there is a guy in charge of updating those dashboards who is forbidden from changing them unless they get approval from some high level person and that person will categorically refuse regardless of the evidence because they want the indicators to be Green.

transcriptase• 5 years ago

This explicitly supports what most of us assume is going on. I wont be surprised if someone with a (un)vested interest will be along shortly to say that their experience is the opposite and that on their team, making people look bad by telling the truth is expected and praised.

version_five• 5 years ago

I had a good chuckle reading your comment. This is not unique to Amazon. Unfortunately, status indicators are super political almost everywhere, precisely because they are what is being monitored as a proxy for the actual progress. I think your comment should be mandatory reading for any leader who is holding the kinds of meetings you describe and thinks they are getting an accurate picture of things.

throwaway82931• 5 years ago

A punitive culture of "accountability" naturally leads to finger pointing and evasion.

belter• 5 years ago

Was this Amazon or AWS?

blowski• 5 years ago

The problem here sounds like lack of clarity over the meaning of the colours.

In organisations with 100s of in-flight projects, it’s understandable that red is reserved for projects that are causing extremely serious issues right now. Otherwise, so many projects would be red, that you’d need a new colour.

tempnow987• 5 years ago

This is not unique. The reason is simple.

1) If you keep status green for 5 years, while not delivering anything, the reality is the folks at the very top (who can come and go) just look at these colors and don't really get into the project UNLESS you say you are red :)

2) Within 1-2 years there is always going to be some excuse for WHY you are late (people changes, scope tweaks, new things to worry about, covid etc)

3) Finally you are 3 years late, but you are launching. Well, the launch overshadows the lateness. Ie, you were green, then you launched, that's all the VP really sees sometime.

dylan6042• 5 years ago

While my boss was on vacation I took over for him in the "Launch readiness" meeting....once a week

Jeez, how many meetings did you go to, and how long was this person's vacation? I'm jelly of being allowed to take that much time off continuously.

subsaharancoder• 5 years ago

I worked at AMZN and this perfectly captures my experience there with those weekly reviews. I once set a project I was managing as "Red" and had multiple SDMs excoriate me for apparently "throwing them under the bus" even though we had missed multiple timelines and were essentially not going to deliver anything of quality on time. I don't miss this aspect of AMZN!

fma• 5 years ago

We have something similar at my big corp company. I think the issue is you went from Green to Red in a flip of a switch. A more normal project goes Green...raise a red flags...if red flags aren't resolved in the next week or two, go to yellow...In these meetings everyone collaborates ways to keep your green or get you back to green if you went yellow.

In essence - what you were saying is your boss lied the whole time, because how does one go from a presumed positive velocity to negative velocity in a week?

Additionally assuming you're a dev lead, it's a little surprising that this is your first meeting of this sorts. As dev lead, I didn't always attend them but my input is always sought on the status.

Sounds like you had a bad manager, and Amazon is filled with them.

tootie3• 5 years ago

I once had the inverse happen. I showed up as an architect at a pretty huge e-commerce shop. They had a project that had just kicked off and onboarded me to help with planning. They had estimated two months by total finger in the air guessing. I ran them through a sizing and velocity estimation and the result came back as 10 months. I explained this to management and they said "ok". We delivered in about 10 months. It was actually pretty sad that they just didn't care. Especially since we quintupled the budget and no one was counting.

syngrog66• 5 years ago

your story reminded me of the Challenger disaster and the "see no evil" bureaucratic shenanigans about the O-rings failing to seal in cold weather.

"How dare you threaten our launch readiness go/no-go?!"

dawnbreez2• 5 years ago

I worked at an Amazon air-shipping warehouse for a couple years, and hearing this confirms my suspicions about the management there. Lower management (supervisors, people actually in the building) were very aware of problems, but the people who ran the building lived out of state, so they only actually went to the building on very rare occasions.

Equipment was constantly breaking down, in ways that ranged from inconvenient to potentially dangerous. Seemingly basic design decisions, like the shape of chutes, were screwed up in mind-boggling ways (they put a right-angle corner partway down each chute, which caused packages to get stuck in the chutes constantly). We were short on equipment almost every day; things like poles to help us un-jam packages were in short supply, even though we could move hundreds of thousands of packages a day. On top of all this, the facility opened with half its sorting equipment, and despite promises that we'd be able to add the rest of the equipment in the summer, during Amazon's slow season...it took them two years to even get started.

And all the while, they demanded ever-increasing package quotas. At first, 120,000 packages/day was enough to raise eyebrows--we broke records on a daily basis in our first holiday rush--but then, they started wanting 200,000, then 400,000. Eventually it came out that the building wouldn't even be breaking even until it hit something like 500,000.

As we scaled up, things got even worse. None of the improvements that workers suggested to management were used, to my knowledge, even simple things like adding an indicator light to freight elevators.

Meanwhile, it eventually became clear that there wasn't enough space to store cargo containers in the building. 737s and the like store packages mostly in these giant curved cargo containers, and we needed them to be locked in place while working around/in them...except that, surprise, the people planning the building hadn't planned any holding areas for containers that weren't in use! We ended up sticking them in the middle of the work area.

Which pissed off the upper management when they visited. Their decision? Stop doing it. Are we getting more storage space for the cans? No. Are we getting more workers on the airplane ramp so we can put these cans outside faster? No. But we're not allowed to store those cans in the middle of the work area anymore, even if there aren't any open stations with working locks. Oh, by the way, the locking mechanisms that hold the cans in place started to break down, and to my knowledge they never actually fixed any of the locks. (A guy from their safety team claims they've fixed like 80 or 90 of the stations since the building opened, but none of the broken locks I've seen were fixed in the 2 years I worked there.)

hvgk2• 5 years ago

This. We're under NDA too on internal support. Our customers know we use AWS and they go and check the AWS status dashboards and tell us there's nothing wrong so the inevitable vitriol is always directed at us which we then have to defend.

macintux• 5 years ago

I guess you have to hope that every outage that impacts you is big enough to make the news.

SkyPuncher• 5 years ago

My company isn't big enough for us to have any pull but this communication is _significantly_ downplaying the impact of this issue.

One of our auxiliary services that's basically a pass through to AWS was offline nearly the entire day. Yet, this communication doesn't even mention that fact. In fact, it almost tries to suggest the opposite.

Likewise, AWS is reporting S3 didn't have issues. Yet, for a period of time, S3 was erroring out frequently because it was responding so slowly.

jiggawatts2• 5 years ago

SLAs with self-reported outage periods are worthless.

SLAs that refund only the cost of the individual service that was down is worthless.

SLAs that require separate proof and refund requests for each and every service that was affected are nearly worthless.

There needs to be an independent body set up by a large cloud customers to monitor availability and enforce refunds.

codegeek• 5 years ago

"Our Support Contact Center also relies on the internal AWS network, so the ability to create support cases was impacted from 7:33 AM until 2:25 PM PST. "

This to me is really bad. Even as a small company, we keep our support infrastructure separate. For a company of Amazon's size, this is a shitty excuse. If I cannot even reach you as a customer for almost 7 hours, that is just nuts. AWS must do better here.

Also, is it true that the outage/status pages are manually updated ? If yes, there is no excuse why it was green for that long. If you are manually updating it, please update asap.

anonu• 5 years ago

Wasn't this the Bezos directive early on that created AWS? Anything that was created had to be a service with an API. Not allowed to recreate the wheel. So AWS depends on AWS.

walrus01• 5 years ago

I know a few tiny ISPs that host their voip server and email server outside of their own ASN so that in the event of a catastrophic network event, communications with customers is still possible... Not saying amazon should do the same, but the general principle isn't rocket science.

there's such as thing as too much dogfooding.

acwan93• 5 years ago

We moved our company's support call system to Microsoft Teams when lockdowns were happening, and even that was affected by the AWS outage (along with our SaaS product hosted on AWS).

It turned out our call center supplier had something running on AWS, and it took out our entire phone system. After this situation settles, I'm tempted to ask my supplier to see what they're doing to get around this in the future, but I doubt even they knew that AWS was used further downstream.

AWS operates a lot like Amazon.com, the marketplace now--you can try to escape it, but it's near impossible. If you want to ban usage of Amazon's services, you're going to find some service (AWS) or even a Shopify site (FBA warehouse) who uses it.

soheil4• 5 years ago

This was addressed at least 3 times during this post. I'm not defending them but you're just gaslighting. If you have something to add about the points they raised regarding the status page please do so.

codeduck2• 5 years ago

carbon copy of our experience.

notyourday• 5 years ago

The entire time their outage board was solid green. We were in touch with their support people and knew it was bad but were under NDA not to discuss it with anyone.

  if ($pain > $gain) {
    move_your_shit_and_exit_aws();
  }

  sub move_your_shit_and_exit_aws
  {
    printf("Dude. We have too much pain. Start moving\n");
    printf("Yeah. That won't happen, so who cares\n");
    exit(1);
  }

secondcoming• 5 years ago

Moving your shit from AWS can be really expensive, depending on how much shit you have. If you're nice, GCP may subsidise - or even cover - the costs!

tuananh2• 5 years ago

even in the post mortem, they are reclutant to admit it

While AWS customer workloads were not directly impacted from the internal networking issues described above, the networking issues caused impact to a number of AWS Services which in turn impacted customers using these service capabilities. Because the main AWS network was not affected, some customer applications which did not rely on these capabilities only experienced minimal impact from this event.

nijave7• 5 years ago

some customer applications which did not rely on these capabilities only experienced minimal impact from this event

Yeah so vanilla LB and EC2 with no autoscaling were fine. Anyone using "serverless" or managed services had a real bad day

tootie3• 5 years ago

Second hand info but supposedly when an outage hits they go all hands on resolving it and no one who knows what's going on has time to update the status board which is why it's always behind.

voidfunc• 5 years ago

Not AWS, but Azure: highly doubt. At least at Azure the moment you declare an outage there is a incident manager to handle customer communication.

Bullshit someone at Amazon doesn’t have time to update the status.

jedberg• 5 years ago

Honestly, the should host that status page on CloudFlare or some completely separate infrastructure that they maintain in colo datacenters or something. The only time it really needs to be up is when their stuff isn't working.

eranation• 5 years ago

Obligatory mention to https://stop.lying.cloud

steveBK123• 5 years ago

Exactly, we had the same thing almost exactly a year ago - https://www.dailymail.co.uk/sciencetech/article-8994907/Wide...

They are barely doing better than 2 9s.

hourislate• 5 years ago

Broadcast storm. Never easy to isolate, as a matter of fact it's nightmarish...

bpodgursky• 5 years ago

DNS?

Of course it was DNS.

It is always* DNS.

tezza• 5 years ago

It is often BGP, regularly DNS, frequently expired keys, sometimes a bad release and occasionally a fire

shepherdjerred2• 5 years ago

This wasn’t caused by DNS. DNS was just a symptom.

simlevesque• 5 years ago

Customers accessing Amazon S3 and DynamoDB were not impacted by this event. However, access to Amazon S3 buckets and DynamoDB tables via VPC Endpoints was impaired during this event.

What does this even mean ? I bet most people use DynamoDB via a VPC, in a Lambda or in EC2

jtoberon• 5 years ago

VPC Endpoint is a feature of VPC: https://docs.aws.amazon.com/vpc/latest/privatelink/endpoint-...

discodave9• 5 years ago

Your application can call DynamoDB via the public endpoint (dynamodb.us-east-1.amazonaws.com). But if you're in a VPC (i.e. practically all AWS workloads in 2021), you have to route to the internet (you need public subnet(s) I think) to make that call.

VPC Endpoints create a DynamoDB endpoint in your VPC, from the documentation:

"When you create a VPC endpoint for DynamoDB, any requests to a DynamoDB endpoint within the Region (for example, dynamodb.us-west-2.amazonaws.com) are routed to a private DynamoDB endpoint within the Amazon network. You don't need to modify your applications running on EC2 instances in your VPC. The endpoint name remains the same, but the route to DynamoDB stays entirely within the Amazon network, and does not access the public internet."

aeyes• 5 years ago

I call my DynamoDB tables via the public endpoint and it was severely impaired - high error rate and very high (second) latency.

all2well• 5 years ago

From within a VPC, you can either access DynamoDB via its public internet endpoints (eg, dynamodb.us-east-1.amazonaws.com, which routes through an Internet Gateway attachment in your VPC), or via a VPC endpoint for dynamodb that's directly attached to your VPC. The latter is useful in cases where you want a VPC to not be connected to the internet at all, for example.

foobarbecue2• 5 years ago

"... the networking congestion impaired our Service Health Dashboard tooling from appropriately failing over to our standby region. By 8:22 AM PST, we were successfully updating the Service Health Dashboard."

Sounds like they lost the ability to update the dashboard. HN comments at the time were theorizing it wasn't being updated due to bad policies (need CEO approval) etc. Didn't even occur to me that it might be stuck in green mode.

wongarsu• 5 years ago

Hasn't this exact thing (something in US-east-1 goes down, AWS loses ability to update dashboard) happened before? I vaguely remember it was one of the S3 outages, but I might be wrong.

In any case, AWS not updating their dashboard is almost a meme by now. Even for global service outages the best you will get is a yellow.

foobarbecue2• 5 years ago

Yeah, probably. I haven't watched it this closely before during an outage. I have no idea if this happens in good faith, bad faith, or (probably) a mix.

dgivney• 5 years ago

In the February 2017 S3 outage, AWS was unable to move status icons to the red icon because those images happened to be stored on the servers that went down.

https://twitter.com/awscloud/status/836656664635846656

llaolleh• 5 years ago

I wonder if they could've designed better circuit breakers for situations like this. They're very common in electrical engineering, but I don't think they're as common in software design. Something we should try to design and put in, actually for situations like this.

EsotericAlgo• 5 years ago

They’re a fairly common design pattern https://en.m.wikipedia.org/wiki/Circuit_breaker_design_patte.... However, they certainly aren’t implemented with the frequency they should be at service level boundaries resulting in these sorts of cascading failures.

riknos314• 5 years ago

One of the big issues mentioned was that one of the circuit breakers they did have (client back off), didn't function properly. So they did have a circuit breaker in the design, but it was broken.

kevin_nisbet• 5 years ago

Netflix was talking alot about circuit breaks a few years ago, and had the Hystrix project. Looks like Hystrix is discontinued, so I'm not sure if there are good library solutions that are easy to adopt. Overall I don't see it getting talked about that frequently... beyond just exponential backoff inside a retry loop.

- https://github.com/Netflix/Hystrix - https://www.youtube.com/watch?v=CZ3wIuvmHeM I think talks about Hystrix a bit, but I'm not sure if it's the presentation I'm thinking of from years ago or not.

isbvhodnvemrwvn3• 5 years ago

In the JVM land resilience4j is the de facto successor of Hystrix:

https://github.com/resilience4j/resilience4j

nayuki• 5 years ago

Operators instead relied on logs to understand what was happening and initially identified elevated internal DNS errors. Because internal DNS is foundational for all services and this traffic was believed to be contributing to the congestion, the teams focused on moving the internal DNS traffic away from the congested network paths. At 9:28 AM PST, the team completed this work and DNS resolution errors fully recovered.

Having DNS problems sounds a lot like the Facebook outage of 2021-10-04. https://en.wikipedia.org/wiki/2021_Facebook_outage

shepherdjerred2• 5 years ago

It’s quite a bit different… Facebook took themselves offline completely because of a bad BGP update, whereas AWS had network congestion due to a scaling event. DNS relies on the network, so of course it’ll be impacting if networking is also impacted.

bdd• 5 years ago

no. it wasn't a "bad bgp update". bgp withdrawal of anycast addresses was a desired outcome of a region (serving location) getting disconnected from the backbone. if you'd like to trivialize it, you can say it was configuration change to the software defined backbone.

human2• 5 years ago

The rule is that it’s always DNS.

jessaustin• 5 years ago

DNS seemed to be involved with both the Spectrum business internet and Charter internet outages overnight. So much for diversifying!

bamboozled2• 5 years ago

Still doesn’t explain the cause of all the IAM permission denied requests we saw against policies which are again working fine without any intervention.

Obviously networking issues can cause any number of symptoms but it seems like an unusual detail to leave out to me. Unless it was another ongoing outage happening at the same time.

a45a33s• 5 years ago

how are auth requests supposed to reach the auth server if the networking is broken?

bamboozled2• 5 years ago

I’d accept this as an answer if I received a timeout or a message to say that.

Permission denied is something altogether because it implies the request reached an authorisation system, was evaluated and denied.

notimetorelax2• 5 years ago

It’s so hard to know what was the state of the system when the monitoring was out. Wouldn’t be surprised if they don’t have the data to investigate it now.

cyounkins3• 5 years ago

My favorite sentence: "Our networking clients have well tested request back-off behaviors that are designed to allow our systems to recover from these sorts of congestion events, but, a latent issue prevented these clients from adequately backing off during this event."

dilap• 5 years ago

Oh you know, an editing error -- they accidentally dropped the word "not".

discodave9• 5 years ago

I saw pleeeeeenty of untested code at Amazon/AWS. Looking back it was almost like the most important services/code had the least amount of testing. While internal boondoggle projects (I worked on a couple) had complicated test plans and debates about coverage metrics.

DrBenCarson3• 5 years ago

This is almost always the case.

The most important services get the most attention from leaders who apply the most pressure, especially in the first ~2y of a fast-growing or high-potential product. So people skip tests.

tootie3• 5 years ago

It's gotta be a whole thing to even think about how to accurately test this kind of software. Simulating all kinds of hardware failures, network partitions, power failures, or the thousand other failure modes.

Then again they get like $100B in revenue that should buy some decent unit tests.

wbsun• 5 years ago

Interesting. I also work for a cloud provider. My team work on both internal infrastructure as well as product features. We take testing coverage very seriously and tie the metrics to the team's perf. Any product feature must have unit tests, integration tests at each layer of the stack, staging test, production test and continuous probers in production. But our reliability is still far from satisfactory. Now with your observation at AWS, I start wondering whether the coverage effort and different types of tests really help or not...

dastbe2• 5 years ago

my take is that the overwhelming majority of services insufficiently invest in making testing easy. the services that need to grow fast due to customer demand skip the tests while the services that aren't going much of anywhere spend way too much time on testing.

a-dub• 5 years ago

this caught my eye as well. i'd wager that it was not configured.

foobiekr2• 5 years ago

thundering herd and accidental synchronization for the win

I am sad to say, I find issues like this any time I look at retry logic written by anyone I have not interacted with previously on the topic. It is shockingly common even in companies where networking is their bread and butter.

cyounkins3• 5 years ago

It absolutely is difficult. A challenge I have seen is when retries are stacked and callers time out subprocesses that are doing retries.

I just find it amusing that they describe their back-off behaviors as "well tested" and in the same sentence, say it didn't back off adequately.

lanstin2• 5 years ago

I found myself wishing for a few code snippets here. It would be interesting. A lot of time code that handles "connection refused" or fast failures doesn't handle network slowness well. I've seen outages from "best effort" services (and the best-effort-ness worked when the services were hard down) because all of a sudden calls that were taking 50 ms were not failing but all taking 1500+ ms. Best effort but no client enforced SLAs that were low enough to matter.

Load shedding never kicked in, so things had to be shutdown for a bit and then restarted.

Seems their normal operating state might be what is called "meta-stable" - dynamically stable at a high thru-put (edited) unless/until a brief glitch bumps the system into the low work being finished state which is also stable.

DenisM2• 5 years ago

Customers accessing Amazon S3 and DynamoDB were not impacted by this event.

We've seen plenty of S3 errors during that period. Kind of undermines credibility of this report.

banana_giraffe3• 5 years ago

Yeah

For example, while running EC2 instances were unaffected by this event

That ignores the 3-5% drop in traffic I saw in us-east-1 on EC2 instances that only talk to peers on the Internet with TCP/IP during this event.

manquer4• 5 years ago

I guess you have to read this kind of items hidden in careful language, running the instances had no problem, it is different matter they had limited connectivity!from AWS point of view they don't seem to see user impact but services from their point of view.

Perhaps that distinction has value if your workloads did not depend on network connectivity externally for example say S3 access without vpc and only compute some DS/ ML jobs perhaps.

grogers• 5 years ago

How are you measuring this? Remember that cloudwatch was apparently also losing metrics, so aggregating CW metrics might show that kind of drop.

davidstoker• 5 years ago

Do you use VPC endpoints for S3? The next sentence explained failures I observed with S3: "However, access to Amazon S3 buckets and DynamoDB tables via VPC Endpoints was impaired during this event."

DenisM2• 5 years ago

No, I use the normal endpoint.

karmelapple• 5 years ago

I could not modify file properties in S3, uploading new or modified files was spotty, and AWS Console GUI access was broken as well. Was that because of VPC endpoints?

marcinzm• 5 years ago

DAX, part of DynamoDB from how AWS groups things, was throwing internal server errors for us and eventually we had to reboot nodes manually. That's separate from the STS issues we had in terms of our EKS services connecting to DAX.

JCM93• 5 years ago

Queue the armchair infrastructure engineers.

The reality is that there’s a handful of people in the world that can operate systems at this sheer scale and complexity and I have mad respect for those in that camp.

tristor• 5 years ago

Some of us are in that camp and are looking at this outage and also pointing out that they continuously fail to accurately update their status dashboard in this and prior outages. Yes, doing what AWS does is hard, and yes outages /will/ happen, it is no knock on them that this outage occurred, what is a knock is that they haven't communicated honestly while the outage was ongoing.

JCM93• 5 years ago

They address that in the post, and between Twitter, HN and other places there wasn’t anyone legit questioning if something was actually broken. Contacts at AWS also all were very clear that yes something was going on and being investigated. This narrative that AWS was pretending nothing was wrong just wasn’t true based on what we saw.

plausibledeny• 5 years ago

Isn't this the equivalent of "complaining about your meal in a restaurant, I'd like to see you do better."

The point of eating at a restaurant is that I can't/don't want to cook. Likewise, I use AWS because I want them to do the hard work and I'm willing to pay for it.

How does that abrogate my right to complain if it goes badly (regardless of whether I could/couldn't do it myself)?

cube00• 5 years ago

I think the distinction is you can say "I pay good money for you to do it properly and how dare you go down on me" but you become an "armchair infrastructure engineer" when you try and explain how you would have avoided the outage because you don't have the whole picture (especially based on a very carefully worded PR approved blog post).

ikiris2• 5 years ago

This outage report reads like a violation of the SRE 101 checklist for networking management though.

StreamBright• 5 years ago

Very detailed.

almostdeadguy• 5 years ago

The AWS container services, including Fargate, ECS and EKS, experienced increased API error rates and latencies during the event. While existing container instances (tasks or pods) continued to operate normally during the event, if a container instance was terminated or experienced a failure, it could not be restarted because of the impact to the EC2 control plane APIs described above.

This seems pretty obviously false to me. My company has several EKS clusters in us-east-1 with most of our workloads running on Fargate. All of our Fargate pods were killed and were unable to be restarted during this event.

ClifReeder• 5 years ago

Strong agree. We were using Fargate nodes in our us-east-1 EKS cluster and not all of our nodes dropped, but every coredns pod did. When they came back up their age was hours older than expected, so maybe a problem between Fargate and the scheduler rendered them “up” but unable to be reached?

Either way, was surprising to us that already provisioned compute was impacted.

silverlyra• 5 years ago

Saw the same. The only cluster services I was running in Fargate were CoreDNS and cluster-autoscaler; thought it would help the clusters recover from anything happening to the node group where other core services run. Whoops.

Couldn't just delete the Fargate profile without a working EKS control plane. I lucked out in that the label selector the kube-dns Service used was disjoint from the one I'd set in the Fargate profile, so I just made a new "coredns-emergency" deployment and cluster networking came back. (cluster-autoscaler was moot since we couldn't launch instances anyway.)

I was hoping to see something about that in this announcement, since the loss of live pods is nasty. Not inclined to rely on Fargate going forward. It is curious that you saw those pod ages; maybe Fargate kubelets communicate with EKS over the AWS internal network?

soheil4• 5 years ago

Having an internal network like this that everything on the main AWS network so heavily depends on is just bad design. One does not create a stable high tech spacecraft and then fuels it with coal.

discodave9• 5 years ago

It's 2006, you work for an 'online book store' that's experimenting with this cloud thing. Are you going to build a whole new network involving multi-million dollar networking appliances?

jvolkman2• 5 years ago

Developing EC2 did involve building a whole new network. It was a new service, built from the ground up to be a public product.

soheil4• 5 years ago

No but one would hope 15 years and 1 trillion dollars later you would stop running it on the computer under your desk.

ripper1138• 5 years ago

Might seem that way because of what happened, but the main network is probably more likely to fail than the internal network. In those cases, running monitoring on a separate network is critical. EC2 control plane same story.

soheil4• 5 years ago

The entire value proposition for AWS is "migrate your internal network to us so it's more stable with less management." I buy that 100%, and I think you're wrong to assume their main network is more likely to fail than their internal one. They have every incentive to continuously improve it because it's not made just for one client.

zeckalpha• 5 years ago

What would you recommend instead? Control plane/data plane is a well known pattern.

yegle• 5 years ago

Was this outage only impact us-east-1 region? I think I saw other regions affected in some HN comments but this summary did not mention anything to suggest it has more than 1 region impacted.

teej• 5 years ago

There are some AWS services, notably STS, that are hosted in us-east-1. I don’t have anything in us-east-1 but I was completely unable to log into the console to check on the health of my services.

azundo• 5 years ago

This resulted in a large surge of connection activity that overwhelmed the networking devices between the internal network and the main AWS network, resulting in delays for communication between these networks. These delays increased latency and errors for services communicating between these networks, resulting in even more connection attempts and retries. This led to persistent congestion and performance issues on the devices connecting the two networks.

I remember my first experience realizing the client retry logic we had implemented was making our lives way worse. Not sure if it's heartening or disheartening that this was part of the issue here.

Our mistake was resetting the exponential backoff delay whenever a client successfully connected and received a response. At the time a percentage but not all responses were degraded and extremely slow, and the request that checked the connection was not. So a client would time out, retry for a while, backing off exponentially, eventually successfully reconnect and then after a subsequent failure start aggressively trying again. System dynamics are hard.

colechristensen2• 5 years ago

System dynamics are hard.

And have to be actually tested. Most of them are designs based on nothing but uninformed intuition. There is an art to back pressure and keeping pipelines optimally utilized. Queueing doesn’t work like you think until you really know.

vmception2• 5 years ago

Most of them are designs based on nothing but uninformed intuition.

Or because they read it on a Google|AWS Engineering blog

gfodor• 5 years ago

Why is this hard, and can’t just be written down somewhere as part of the engineering discipline? This aspect of systems in 2021 really shouldn’t be an “art.”

EnlightenedBro3• 5 years ago

But what's a good alternative then? What if the internet connection has recovered? And you were at the, for example, 4 minute retry loop. Would you just make your users stare at a spinning loader for 8 minutes?

xmprt• 5 years ago

I first learned about exponential backoff from TCP and TCP has a lot of other smart ways to manage congestion control. You don't need to implement all the ideas into client logic but you can also do a lot better than just basic exponential backoff.

kqr2• 5 years ago

Sure, why not?

Or tell them directly that "We have screwed up. The service is currently overloaded. Thank you for your patience. If you still haven't given up on us, try again a less busy time of day. We are very sorry."

There are several options, and finding the best one depends a bit on estimating the behaviour of your specific target audience.

sciurus• 5 years ago

See for instance the client request rejection probability equation at https://sre.google/sre-book/handling-overload/

heisenbit• 5 years ago

The problem shows up at the central system while the peripheral device is causing it. And those systems belong to very different organizations with very different priorities. I still remember how difficult the discussion was with 3G basestation team persuading them to implement exponential backoff with some random factor when connecting to the management system.

markus_zhang• 5 years ago

At 7:30 AM PST, an automated activity to scale capacity of one of the AWS services hosted in the main AWS network triggered an unexpected behavior from a large number of clients inside the internal network.

Just curious, is this scaling an AWS job or a client job? Looks like an AWS one from the context. I'm wondering if they are deploying additional data centers or something else?

whatever1• 5 years ago

Noob question, but why does network infrastructure need dns? Why the full ipv6 address of the various components do not suffice to do business?

nijave7• 5 years ago

It's basically used for service discovery. At a certain point, you have too many different devices which are potentially changing to identify them by IP. You want some abstraction layer to separate physical devices from services and DNS lets you so things like advertise different IPs at different times in different network zones

AUX4R6829DR82• 5 years ago

That "internal network" hosts an awful lot of stuff- it's not just network hardware, but services that mostly use DNS to find each other. Besides that, it's just plain useful for network devices to have names.

(Source: Work at AWS.)

betaby• 5 years ago

Problem is that I have to defend our own infrastructure real availability numbers vs cloud's fictional "five nines". It's a loosing game.

Spivak2• 5 years ago

All I’m hearing is that you can make up your own availability numbers and get away with it. When you define what it means to be up or down then reality is whatever you say it is.

#gatekeep your real availability metrics

#gaslight your customers with increased error rates

#girlboss

WoahNoun• 5 years ago

What are you trying to imply with that last hashtag?

mpyne• 5 years ago

Some orgs really do have lousy availability figures (such as my own, the Navy).

We have an environment we have access to for hosting webpages for one of the highest leaders in the whole Dept of Navy. This environment was DOWN (not "degrade availability" or "high latencies"), literally off of the Internet entirely, for CONSECUTIVE WEEKS earlier this year.

Completely incommunicado as well. It just happened to start working again one day. We collectively shrugged our shoulders and resumed updating our part of it.

This is an outlier example but even our normal sites I would classify as 1 "nine" of availability at best.

garbagecoder• 5 years ago

Army, here. We're no better. And of course a few years back the whole system for issuing CACs was off for DAYS.

EnlightenedBro3• 5 years ago

This feels like it's a common thing in large enterprisey companies. Execs out of touch with technical teams, always pushing for more for less.

ngc2482• 5 years ago

Yep, things should be made clear to whoever cares about your service's SLA that our SLA is contingent upon AWS's SLA et al. AWS' SLA would be the lower bound :)

tyingq• 5 years ago

"Amazon Secure Token Service (STS) experienced elevated latencies"

I was getting 503 "service unavailable" from STS during the outage most of the time I tried calling it.

I guess by "elevated latency", they mean from anyone with retry logic that would keep trying after many consecutive attempts?

jrockway• 5 years ago

I suppose all outages are just elevated latency. Has anyone ever had an outage and said "fuck it, we're going out of business" and never came back up? That's the only true outage ;)

hericium3• 5 years ago

5xx errors are servers or proxies giving up on requests. Increased timeouts resulting in successful requests may have been considered "elevated latency" (but rarely this would be a proper way to solve similar issue).

They treat 5xx errors as non-errors but this is not the case with rest of the world. "Increased timeouts" is Amazon's untruthful term for "not working at all".

WaxProlix2• 5 years ago

STS is the worst with this. Even for other internal teams, they seem to treat dropped requests (ie, timeouts which represent 5xxs on the client side) as 'non faults', and so don't treat those data points in their graphs and alarms. It's really obnoxious.

AWS in general is trying hard to do the right thing for customers, and obviously has a long ways to go. But man, a few specific orgs have some frustrating holdover policies.

hericium3• 5 years ago

AWS in general is trying hard to do the right thing for customers

You are responding to a comment that suggests they're misrepresenting the truth (which wouldn't be the first time even in last few days) in communication to their customers.

As always, they are doing the right thing for themselves only.

EDIT: I think that you should mention being an Engineer at Amazon AWS in your comment.

comboy• 5 years ago

So many lessons in this article. When your service goes down but eventually gets back up, it's not an outage. It's "elevated latency". Of a few hours, maybe days.

sneak• 5 years ago

"impact" occurs 27 times on this page.

What was wrong with "affect"?

pohl• 5 years ago

The easiest way to avoid confusing affect with effect is to use other words.

wjossey6• 5 years ago

I’ve been running platform teams on aws now for 10 years, and working in aws for 13. For anyone looking for guidance on how to avoid this, here’s the advice I give startups I advise.

First, if you can, avoid us-east-1. Yes, you’ll miss new features, but it’s also the least stable region.

Second, go multi AZ for production workloads. Safety of your customer’s data is your ethical responsibility. Protect it, back it up, keep it as generally available as is reasonable.

Third, you’re gonna go down when the cloud goes down. Not much use getting overly bent out of shape. You can reduce your exposure by just using their core systems (EC2, S3, SQS, LBs, Cloudfrount, RDS, Elasticache). The more systems you use, the less reliable things will be. However, running your own key value store, api gateway, event bud, etc., can also be way less reliable than using their’s. So, realize it’s an operational trade off.

Degradation of your app / platform is more likely to come from you than AWS. You’re gonna roll out bad code, break your own infra, overload your own system, way more often than Amazon is gonna go down. If reliability matters to you, start by examining your own practices first before thinking things like multi region or super durable highly replicated systems.

This stuff is hard. It’s hard for Amazon engineers. Hard for platform folks at small and mega companies. It’s just, hard. When your app goes down, and so does Disney plus, take some solace that Disney in all their buckets of cash also couldn’t avoid the issue.

And, finally, hold cloud providers accountable. If they’re unstable and not providing service you expect, leave. We’ve got tons of great options these days, especially if you don’t care about proprietary solutions.

Good luck y’all!

daguava• 5 years ago

You've written up my thoughts better than I can express them myself - I think what people get really stuck on when something like this happens is the 'can I solve this myself?' aspect.

A wait for X provider to fix it for you situation is infinitely more stressful than an 'I have played myself, I will now take action' situation.

Situations out of your (immediate) resolution control feel infinitely worse, even if the customer impact in practice of your fault vs cloud fault is the same.

dalyons• 5 years ago

For me it’s the opposite… aws outages are much less stressful than my own because I know there’s nothing I/we can do about it, they have smart people working on it, and it will be fixed when it’s fixed

electroly4• 5 years ago

I couldn't possibly disagree more strongly with this. I used to drive frantically to the office to work on servers in emergency situations, and if our small team couldn't solve it, there was nobody else to help us. The weight of the outage was entirely on our shoulders. Now I relax and refresh a status page.

manquer4• 5 years ago

Easy to say leave, the techinical lockin cloud service providers by design choose to have makes it impossible to leave .

AWS (and others) make egress costs insanely expensive for any startup to consider leaving with their data, also there is constant push to either not support open protocols or extend /expand them in ways making it hard to migrate a code base easily.

If the advise is to use only effectively use managed open source components then why AWS at all ? most competent mid sized teams can do that much cheaper with a colo providers like OVH/hetzner.

The point of investing in AWS is not outsource running base infra, if we should stay away from leveraging the kind of cloud native services us mere mortals cannot hope to build or maintain.

Also this avoid us-east-1 advice is bit frustrating, AWS does not have to experiment with new services always in the same region,it is not marked as experimental region or has reduced SLAs , if it is inferior/preview/beta than call it out in the UI and contract, what about when there is no choice? If cloudfront is managed in us-east-1 and we shouldnt now use it ? Why use the cloud then ?

if your engineering only discovers scale problems at us-east-1 along with customers perhaps something is wrong ? aws could limit new instances in that region and spread the load, playing with customers like this who are at your mercy just because you can is not nice.

Disney can afford to go down, or build their cloud, small companies don't have deep pockets to do either

cherioo• 5 years ago

AWS (and others) make egress costs insanely expensive for any startup to consider leaving with their data

I have seen this repeated many times, but don't understand it. Yes egress is expensive, but they are not THAT expensive compared to storage. S3 egress per GB is no more than 3x the price of storage, i.e. moving out just cost 3 month of storage cost (there's also API cost but that's not the one often mentioned).

Is egress pricing being a lock-in factor just a myth? Is there some other AWS cost I'm missing? Obviously there will be big architectural and engineering cost to move, but that's just part of life.

EnlightenedBro3• 5 years ago

Lesson to build your services with Docker and Terraform. In this setup you can spin up a working clone of a decently sized stack in a different cloud provider in under an hour.

Don't lock yourself in.

oasisbob2• 5 years ago

Third, you’re gonna go down when the cloud goes down. Not much use getting overly bent out of shape.

Ugh. I have a hard time with this one. Back in the day, EBS had some really awful failures and degradations. Building a greenfield stack that specifically avoided EBS and stayed up when everyone else was down during another mass EBS failure felt marvelous. It was an obvious avoidable hazard.

It doesn't mean "avoid EBS" is good advice for the decade to follow, but accepting failure fatalistically doesn't feel right either.

wjossey6• 5 years ago

I hear you. I didn’t use EBS for five years after the great outage in, what was it, 2011?

At this point, it’s reliable enough that even if it were to go down, it’s more safe than not using it. I’d put EBS in the pantheon of “core” services I never mind using these days.

speedgoose2• 5 years ago

Third, you’re gonna go down when the cloud goes down.

Not necessarily. You just need to not be stuck with a single cloud provider. The likelihood of more than one availability zone going down on a single cloud provider is not that low in practice. Especially when the problem is a software bug.

The likelihood of AWS, Azure, and OVH going down at the same time is low. So if you need to stay online if AWS fail, don't put all your eggs in the AWS basket.

That means not using proprietary cloud solutions from a single cloud provider, it has a cost so it's not always worth it.

chii• 5 years ago

using proprietary cloud solutions from a single cloud provider, it has a cost so it's not always worth it.

but perhaps some software design choices could be made to alleviate these costs. For example, you could have a read-only replica on azure or whatever backup cloud provider, and design your software interfaces to allow the use of such read only replicas - at least you'd be degraded rather than unavailable. Ditto with web servers etc.

This has a cost, but it's lower than entirely replicating all of the proprietary features in a different cloud.

bombcar• 5 years ago

True multi-cloud redundancy is hard to test - because it’s everything from DNS on up and it’s hard to ask AWS to go offline so you can verify Azure picks up the slack.

bradknowles6• 5 years ago

Complex systems are expensive to operate, in many ways.

The more complexity you build into your own systems on top of the providers you depend on, the more likely you are to shoot yourself in the foot when you run into complexity issues that you’ve never seen before.

And the times that is most likely to happen is when one of your complex service providers goes down.

If the kind of thing you’re talking about could be feasibly done, then Netflix would have already done it. The fact that Netflix hasn’t solved this problem is a strong indicator that piling more proprietary complexity on top of all the vendor complexity you inherit from using a given service, well that’s a really hard problem in and of itself.

chrisweekly2• 5 years ago

Hey Wes! I upvoted your comment before I noticed your handle. +1 insightful, as usual

mobutu• 5 years ago

Brown nose

qwertyuiop_2• 5 years ago

Or rent bare metal servers like old times and be responsible for your own s*t

aenis• 5 years ago

Still plenty of networking issues that can knock you down hard.

xyst2• 5 years ago

And, finally, hold cloud providers accountable. If they’re unstable and not providing service you expect, leave. We’ve got tons of great options these days, especially if you don’t care about proprietary solutions.

Easy to say, but difficult to do in practice (leaving a cloud provider)

wjossey6• 5 years ago

Absolutely hard. But that doesn’t mean if you’re in a position to start a company from scratch that you can’t walk away. Or if you go to another company and are involved in their procurement of a new purchase, that you can’t sway it away from said provider.

Just because it takes years doesn’t meant it can’t happen.

kortilla3• 5 years ago

Safety of your customer’s data is your ethical responsibility. Protect it, back it up, keep it as generally available as is reasonable.
Third, you’re gonna go down when the cloud goes down. Not much use getting overly bent out of shape.

“Whoops, our provider is down, sorry!” is not taking responsibility with customer data at all.

wjossey6• 5 years ago

Respectfully disagree. No company in the world has 100% uptime. Whether it’s your server rack or their server rack going down means nothing to a customer.

We’re not discussing data loss in this thread specifically. This is about a couple of hours of downtime per year.

wly_cdgr• 5 years ago

Their service board is always as green as you have to be to trust it

AtlasBarfed• 5 years ago

"At 7:30 AM PST, an automated activity to scale capacity of one of the AWS services hosted in the main AWS network triggered an unexpected behavior from a large number of clients inside the internal network. This resulted in a large surge of connection activity that overwhelmed the networking devices between the internal network and the main AWS network, resulting in delays for communication between these networks. These delays increased latency and errors for services communicating between these networks, resulting in even more connection attempts and retries."

So was this in service to something like DynamoDB or some other service?

As in, did some of those extra services that AWS offers for lockin (and that undermines open source projects with embrace and extend) bomb the mainline EC2 service?

Because this kind of smacks of "Microsoft Hidden APIs" that office got to use against other competitors. Does AWS use "special hardware capabilites" to compete against other companies offering roughtly the same service?

nijave7• 5 years ago

Yes and other cloud providers (Google, Microsoft) probably have similar. Besides special network equipment, they use PCIe accelerator/coprocessors on their hypervisors to offload all non-VM activity (Nitro instances)

They also recently announced Graviton ARM CPUs

User232• 5 years ago

A packet storm outage? Now that brings back memories. Last time I saw that it was rendezvous misbehaving.

rodmena• 5 years ago

umm... But just one thing, S3 was not available at least for 20 minutes.

divbzero• 5 years ago

This congestion immediately impacted the availability of real-time monitoring data for our internal operations teams, which impaired their ability to find the source of congestion and resolve it.

Disruption of the standard incident response mechanism seems to be a common element of longer lasting incidents.

femiagbabiaka2• 5 years ago

It is. And to add, all automation that we rely on in peace time can often complicate cross cutting wartime incidents by raising the ambient complexity of an environment. Bainbridge for more: https://blog.acolyer.org/2020/01/08/ironies-of-automation/

daenney• 5 years ago

Yup. There was a GCP outage a couple of years ago like this.

I don’t remember the exact details, but it was something along the lines of a config change went out that caused systems to incorrectly assume there were huge bandwidth constraints. Load shedding kicked in to drop lower priority traffic which ironically included monitoring data rendering GCP responders blind and causing StackDriver to go blank for customers.

sponaugle2• 5 years ago

Indeed - Even the recent facebook outage outlined how slow recovery can be if the primary investigation and recovery methods are directly impacted as well. Back in the old days some environments would have POTS dial-in connections to the consoles as backup for network problems. That of course doesn't scale, but it was an attempt to have an alternate path of getting to things. Regrettably if a backhoe takes out all of the telecom at once that plan doesn't work so well.

qwertyuiop_2• 5 years ago

House of cards

onion2k• 5 years ago

This congestion immediately impacted the availability of real-time monitoring data for our internal operations teams

I guess this is why it took ages for the status page to update. They didn't know which things to turn red.

jetru3• 5 years ago

Complex systems are really really hard. I'm not a big fan of seeing all these folks bash AWS for this, and not really understanding the complexity or nastiness of situations like this. Running the kind of services they do for the kind of customers, this is a VERY hard problem.

We ran into a very similar issue, but at the database layer in our company literally 2 weeks ago, where connections to our MySQL exploded and completely took down our data tier and caused a multi-hour outage, compounded by retries and thundering herds. Understanding this problem under the stressful scenario is extremely difficult and a harrowing experience. Anticipating this kind of issue is very very tricky.

Naive responses to this include "better testing", "we should be able to do this", "why is there no observability" etc. The problem isn't testing. Complex systems behave in complex ways, and its difficult to model and predict, especially when the inputs to the system aren't entirely under your control. Individual components are easy to understand, but when integrating, things get out of whack. I can't stress how difficult it is to model or even think about these systems, they're very very hard. Combined with this knowledge being distributed among many people, you're dealing with not only distributed systems, but also distributed people, which adds more difficulty in wrapping this around your head.

Outrage is the easy response. Empathy and learning is the valuable one. Hugs to the AWS team, and good learnings for everyone.

fastball• 5 years ago

I think most of the outrage is not because "it happened" but because AWS is saying things like "S3 was unaffected" when the anecdotal experience of many in this thread suggests the opposite.

That and the apparent policy that a VP must sign off on changing status pages, which is... backwards to say the least.

jetru3• 5 years ago

There's definitely miscommunication around this. I know I've miscommunicated impact, or my communication was misinterpreted across the 2 or 3 people it had to jump before hitting the status page.

For example, The meaning of "S3 was affected" is subject to a lot of interpretation. STS was down, which is a blocker for accessing S3. So, the end result is S3 is effectively down, but technically it is not. How does one convey this in a large org? You run S3, but not STS, it's not technically an S3 fault, but an integration fault across multiple services. If you say S3 is down, you're implying that the storage layer is down. But it's actually not. What's the best answer to make everyone happy here? I cant think of one.

amzn-throw• 5 years ago

a VP must sign off on changing status pages, which is... backwards to say the least.

I think most people's experience with "VP's" makes them not realize what AWS VP's do.

VP's here are not sitting in an executive lounge wining and dining customers, chomping on cigars and telling minions to "Call me when the data center is back up and running again!"

They are on the tech call, working with the engineers, evaluating the problem, gathering the customer impact, and attempting to balance communicating too early with being precise.

Is there room for improvement? Yes. I wish we would just throw up a generic "Shit's Fucked Up. We Don't Know Why Yet, But We're Working On It" message.

But the reason why we don't, doesn't have anything to do with having to get VP approval to put that message up. The VP's are there in the trenches most of the time.

metb• 5 years ago

Thanks for these thoughts. Resonated well with me. I feel we are sleepwalking into major fiascos, when a simple doorbell needs to sit on top this level of complexity. It's in our best interest to not tie every small thing into layers, and layers of complexity. Mundane things like doorbells need to have their fallback at least done properly to function locally without relying on complex cloud systems.

xamde• 5 years ago

There is this really nice website which explains how complex systems fail: https://how.complexsystems.fail/

simonbarker87• 5 years ago

I’m not all that angry over the situation but more disappointed that we’ve all collectively handed the keys over to AWS because “servers are hard”. Yeh they are but it’s not like locking ourselves into one vendor with flaky docs and a black box of bugs is any better, at least when your own servers go down it’s on you and you don’t take out half of North America.

nix234• 5 years ago

Servers are not hard if you have a dedicated person (long time ago known as Systemadminstrator), and fun fact...it's sometimes even much cheaper and more reliable then having everything in the "cloud".

Personally i am a believer in mixed environments, public webservers etc in the "cloud", locally used systems and backup "in house" with a second location (both in Data-centers or at least one), and no, i don't talk about the next google but the 99% of businesses.

ranguna2• 5 years ago

You can either pay a dedicated team to manage your on prem solution, go multi cloud, or simply go multi region on aws.

My company was not affected by this outage because we are multi region. Cheapest and quickest option if you want to have at least some fault tolerance.

linsomniac• 5 years ago

If you aren't going to rely on external vendors, servers are really, really hard. Redundancy in: power, cooling, networking? Those get expensive fast. Drop your servers into a data center and you're in a similar situation to dropping it in AWS.

A couple years ago all our services at our data center just vanished. I call the data center and they start creating a ticket. "Can you tell me if there is a data center outage?" "We are currently investigating and I don't have any information I can give you." "Listen, if this is a problem isolated to our cabinet, I need to get in the car. I'm trying to decide if I need to drive 60 miles in a blizzard."

That facility has been pretty good to us over a decade, but they were frustratingly tight-lipped about an entire room of the facility losing power because one of their power feeder lines was down.

Could AWS improve? Yes. Does avoiding AWS solve these sorts of problems? No.

raffraffraff3• 5 years ago

Interesting. Just wondering if your guys have a dedicated DBA?

raffraffraff3• 5 years ago

Not sure why I got down voted for an honest question. Most start-ups are founders, developers, sales and marketing. Dedicated infrastructure, network and database specialists don't get factored in because "smart CS graduates can figure that stuff out". I've worked at companies who held onto that false notion way too long and almost lost everything as a result ("company extinction event", like losing a lot of customer data)

qaq• 5 years ago

Very good summary of why small projects need to think real hard before jumping onto microservices bandwagon.

tuldia3• 5 years ago

Excuse me, do we need all that complexity? Telling that it is "hard" is justifiable?

It is naive to assume people bashing AWS are uncapable to running things better, cheaper, faster, across many other vendors, on-prem, colocation or what not.

Outrage is the easy response.

That is what made AWS get the marketshare it has now in the first place, the easy responses.

The main selling point of AWS in the beginning was "how easy is to sping a virtual machine". After basically every layman started recommending AWS and we flocked there, AWS started making things more complex than it should. Was that to make harder to get out of it? IDK.

Empathy and learning is the valuable one.

When you run your infrastructure and something fails and you are not transparent, your users will bash you, independently who you are.

And that was another "easy response" used to drive companies towards AWS. We developers were echoing that "having a infrastructure team or person is not necessary", etc.

Now we are stuck in this learned helplessness where every outage is a complete disaster in terms of transparency, multiple services failing, even for multi-region and multi-az customers, we saying "this service here is also not working" and AWS simple states that service was fine, not affected, up and running.

If it was a sysadmin doing that, people will be asking for his/her neck with pitchforks.

noahtallen• 5 years ago

AWS started making things more complex than it should

I don’t think this is fair for a couple reasons:

1. AWS would have had to scale regardless just because of the number of customers. Even without adding features. This means many data centers, complex virtual networking, internal networks, etc. These are solving very real problems that happen when you have millions of virtual servers.

2. AWS hosts many large, complex systems like Netflix. Companies like Netflix are going to require more advanced features out of AWS, and this will result in more features being added. While this is added complexity, it’s also solving a customer problem.

My point is that complexity is inherent to the benefits of the platform.

iso16312• 5 years ago

I'm not a big fan of seeing all these folks bash AWS for this,

The disdain I saw was towards those claiming that all you need is AWS, that AWS never goes down, and don't bother planning for what happens when AWS goes down.

AWS is an amazing accomplishment, but it's still a single point of failure. If you are a company relying on a single supplier and you don't have any backup plans for that supplier being unavailable, that is ridiculous and worthy of laughter.

Ensorceled4• 5 years ago

Outrage is the easy response. Empathy and learning is the valuable one.

I'm outraged that AWS, as a company policy, continues to lie about the status of their systems during outages, making it hard for me to communicate to my stakeholders.

Empathy? For AWS? AWS is part a mega corporation that is closing in on 2 TRILLION dollars in market cap. It's not a person. I can empathize with individuals who work for AWS but it's weird to ask us to have empathy for a massive faceless, ruthless, relentless, multinational juggernaut.

Jgrubb• 5 years ago

It seems obvious to me that they're specifically talking about having empathy for the people who work there, the people who designed and built these systems and yes, empathy even for the people who might not be sure what to put on their absolutely humongous status page until they're sure.

ithkuil• 5 years ago

My reading of GP's comment is that the empathy should be directed towards AWS' team, the people who are building the system and handling the fallout, not AWS the corporate entity.

I may be wrong, but I try to apply the https://en.m.wikipedia.org/wiki/Principle_of_charity

danjac• 5 years ago

The problem isn't AWS per se. The problem is it's become too big to fail. Maybe in the past an outage might take down a few sites, or one hospital, or one government service. Now one outage takes out all the sites, all the hospitals and all the government services. Plus your coffee machine stops working.

spfzero• 5 years ago

But Amazon advertises that they DO understand the complexity of this, and that their understanding, knowledge and experience is so deep that they are a safe place to put your critical applications, and so you should pay them lots of money to do so.

Totally understand that complex systems behave in incomprehensible ways (hopefully only temporarily incomprehensible). But they're selling people on the idea of trading your complex system, for their far more complex system that they manage with such great expertise that it is more reliable.

bradknowles6• 5 years ago

They don’t sell “guaranteed no downtime throughout the history of the universe”.

They have SLAs. And there are clauses that cover the weird edge cases for when the SLAs are not met.

revskill• 5 years ago

Most of rate limiter system often drop invalid requests, it's not optimal as i see.

The better way is, we should have two queues, one for valid messages and one for invalid messages.

xyst2• 5 years ago

I am not a fan of AWS due to their substantial market share on cloud computing. But as a software engineer I do appreciate their ability to provide fast turnarounds on root cause analyses and make them public.

waz0wski• 5 years ago

This isn't a good example of an RCA - as other commenters have noted, it's outrightly lying about some issues during the incident, and using creative language to dance around other problems many people encountered.

If you want to dive into postmortems, there are some repos linking other examples

https://github.com/danluu/post-mortems

https://codeberg.org/hjacobs/kubernetes-failure-stories

amznbyebyebye• 5 years ago

I’m glad they published something, that too so quick. Ultimately these guys are running a business. There are other market alternatives, multibillion dollar contracts at play, SLAs, etc. it’s not as simple as people think.

herodoturtle2• 5 years ago

I am grateful to AWS for this report.

Not sure if any AWS support staff are monitoring this thread, but the article said:

Customers also experienced login failures to the AWS Console in the impacted region during the event.

All our AWS instances / resources are in EU/UK availability zones, and yet we couldn't access our console either.

Thankfully none of our instances were affected by the outage, but our inability to access the console was quite worrying.

Any idea why this was this case?

Any suggestions to mitigate this risk in the event of a future outage would be appreciated.

plasma• 5 years ago

They posted on the status page to try using the alternate region endpoints like us-west.console.Amazon.com (I think) at the time, but not sure if it was a true fix.

raffraffraff3• 5 years ago

Something they didn't mention is AWS Billing alarms. These rely on metrics systems which were affected by this (and are missing some data). Crucially, billing alarms only exist in the us-east-1 region, so if you're using them, your impacted no matter where you're infrastructure is deployed. (That's just my reading of it)

londons_explore• 5 years ago

Idea:. Network devices should be configured to automatically prioritize the same packet flows for the same clients as they served yesterday.

So many overload issues seem to be caused by a single client, in a case where the right prioritization or rate limit rule could have contained any outage, but such a rule either wasn't in place or wasn't the right one due to the difficulty of knowing how to prioritize hundreds of clients.

Using more bandwidth or requests than yesterday should then be handled as capacity allows, possibly with a manual configured priority list, cap, or ratio. But "what I used yesterday" should always be served first. That way, any outage is contained to clients acting differently to yesterday, even if the config isn't perfect.

stevefan1999• 5 years ago

In a nutshell: thundering herd.

Ensorceled4• 5 years ago

There are a lot of comments in here that boil down to "could you do infrastructure better?"

No, absolutely not. That's why I'm on AWS.

But what we are all ACTUALLY complaining about is ongoing lack of transparent and honest communications during outages and, clearly, in their postmortems.

Honest communications? Yeah, I'm pretty sure I could do that much better than AWS.

moogly2• 5 years ago

Hm. This post does not seem to acknowledge what I saw. Multiple hours of rate-limiting kicking in when trying to talk to S3 (eu-west-1). After the incident everything works fine without any remediations done on our end.

MrBurnsa• 5 years ago

eu-west-1 was not impacted by this event. I’m assuming you saw 503 Slowdown responses, which are non-exceptional and happen for a multitude of reasons.

moogly2• 5 years ago

I see. Then I suppose that was an unfortunately timed happenstance (and we should look into that more closely).

sponaugle2• 5 years ago

"Our networking clients have well tested request back-off behaviors that are designed to allow our systems to recover from these sorts of congestion events, but, a latent issue prevented these clients from adequately backing off during this event. "

That is an interesting way to phrase that. A 'well-tested' method, but 'latent issues'. That would imply the 'well-tested' part was not as well-tested as it needed to be. I guess 'latent issue' is the new 'bug'.

paulryanrogers• 5 years ago

Has anyone been credited by AWS for violations of their SLAs?

atoav• 5 years ago

A "service event"?!

Summary of the AWS Service Event in the Northern Virginia (US-East-1) Region

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