Pushing Nginx to its limit with Lua

http://blog.cloudflare.com/pushing-nginx-to-its-limit-with-lua

by jgrahamc • 14 years ago

201 57 14 years ago

blog.cloudflare.com

zrail• 14 years ago

I used OpenResty as the core for an experimental HTTP routing service at my previous job. The idea was to maintain host:port pairs for HTTP services in Redis and use a small bit of Lua code to look up the right place to proxy a virtual host to. It worked well enough, but never got deployed because we were concerned about the Redis SPOF. Now-a-days it wouldn't be that big of a deal.

That said, the nginx/lua combo is wonderful to work with. I got the core of that thing working in just a few hours.

moonboots• 14 years ago

I'm using nginx+lua as the backend to http://typing.io, and I've found the combination to be a fast and robust alternative to more full featured web stacks like Rails.

smegel• 14 years ago

But what happens when people put big numbers in my Fibonacci calculator?

cheald• 14 years ago

Lua implements TCO, so it'll do just fine. :P

dbaupp3• 14 years ago

If we are being pedantic, the naive Fibonacci implementation isn't tail recursive. (And any tail recursive implementation is unlikely to need TCO before the numbers get too large.)

stcredzero2• 14 years ago

It would seem that this approach gives all the advantages of async with none of the drawbacks involved with writing callbacks. If someone added a type annotation extension to the language and parser, this would be a killer combination for large code bases. Lua is also a good match for "The Good Parts" of Javascript, so it should be possible to have all the code in one language.

kyrra• 14 years ago

Lua was never designed to be used for really large code basis. It's a lightweight scripting language on top of C. The entire runtime is written in 20k lines of C. It also is designed to be easily incorporated in C programs. Nginx is a popular server case, while World Of Warcraft is another popular us.

It's really a pretty amazing language, when you embed it you can choose exact what functionality is exposed to the scripts you run in it, so it's pretty good for sandboxes type code (though, imposing memory restrictions is much harder).

stcredzero2• 14 years ago

Lua was never designed to be used for really large code basis.

Bases. That doesn't mean that it wouldn't be good for large code bases. Many languages end up getting used for purposes they weren't designed for.

_dps2• 14 years ago

> Lua was never designed to be used for really large code basis

I'd certainly agree that "maintainable for large code bases" was probably never on Ierusalimschy & Co's language design requirements document, but you could say the same of same of Perl, Python, Ruby, Javascript, and most Lisps. None of those languages have any additional mechanisms traditionally associated with enforcing uniformity and consistency across large projects. This hasn't stopped people from building large successful projects using these languages.

As for your comment on the implementation size: I'm not sure which way you meant it (complimentary or pejorative) but I often find people react to this in exactly the opposite fashion I would. I see "self-ish/JS-ish/python-ish semantics in 20kloc of ANSI C? Sign me up!". I find some people see it and assume it to be a toy. It reminds me of the Bill Gates line about (paraphrasing) "measuring software's success by lines of code is like measuring an aircraft's success by its weight".

neopallium• 14 years ago

> (though, imposing memory restrictions is much harder).

I developed an Emergency GC patch [1] for Lua 5.1 (Lua 5.2 come with this feature). With this feature it is easy set a per Lua State/script memory limit. The Emergency GC feature is needed to allow a custom allocator to force the GC to run when the script is at it's memory limit. My EGC patch has been in use by the eLua [2] for years to help run Lua scripts on Microcontrollers with as little as 64Kbytes of Ram.

Also Lua is fine for large projects [3].

1. http://lua-users.org/wiki/EmergencyGarbageCollector

2. http://www.eluaproject.net/

3. http://prosody.im/

tomlu• 14 years ago

IME Lua is neither worse nor better than (eg) Python for large code bases.

InclinedPlane2• 14 years ago

Javascript was written by one guy in a shockingly short amount of time. What a language was intended for and what it's capable of are two very different things.

ufo2• 14 years ago

When I looked at their code I couldn't really find how they are dealing with the async stuff. Is it using coroutines or is it something else?

qnk2• 14 years ago

I'm really glad to see a Cloudflare post at the top of Hacker News, I've been following them and they have lots of interesting things to say. I switched from Amazon Cloudfront to Cloudflare two months ago and can't be happier. My hosting bill was reduced a 95% and my website speed decreased only a 13%, a figure my weekend project can afford to make it profitable.

eastdakota5• 14 years ago

Don't like that one bit. No reason your speed should decrease at all. That's quite different from other people's experience comparing CloudFlare to CloudFront. If you have a second, submit a ticket and we'll make sure you've got everything setup for maximum performance.

qnk2• 14 years ago

Thanks for your concern Matthew, I'm not very worried about this. That 13% of difference in speed is most probably due to the fact that Amazon has a Cloudfront edge location in Madrid, the city most of my traffic comes from.

I haven't really measured the speed from other locations but I will do it and file the ticket to let you know about it.

saurik5• 14 years ago

What caused the reduction in your hosting bill? Was it Amazon's supposedly-poor cache hit ratio, or a CloudFlare-specific feature? Have you tried negotiating with a larger CDN?

eastdakota5• 14 years ago

CloudFlare typically reduces bandwidth usage and load by about 70%. That can translate into cost savings if your host (e.g., AWS) charges you for bandwidth.

donavanm• 14 years ago

Can you elaborate on CloudFronts "poor cache hit ratio"? Wouldn't this just be up to the origins use of cache headers (cache-control, expires, etc)? I suppose cold content could be LRUd out, but the CloudFront docs advertise advertise 1 day last I looked. PS CloudFront customer access logs include cache result (hit/miss/error) so you can see for yourself.

jumby2• 14 years ago

Why doesn't everyone try Apache Traffic Server with its LUA plugin which has way better performance and many more capabilities?

tsewlliw• 14 years ago

That sounds interesting. Want to post your writeup of your experience with it?

piotrSikora• 14 years ago

> has way better performance

Do you have any performance comparison?

> many more capabilities

As...? Care to compare?

jumby2• 14 years ago

How about honoring the RFC's as a first comparison as to capabilities. Example: nginx doesn't even honor Vary headers:

http://trac.nginx.org/nginx/ticket/118

justincormack2• 14 years ago

(a) no evidence of better performance. Lua/Nginx is very fast too. (b) Its just a proxy, while Lua/Nginx/openresty is much more of a full web development environment. You can use it as a proxy, but it is not the main use case. (c) I don't think Traffic Server has more capabilities, as far as I can see, I think it has fewer as it is much more focus on being a proxy product, while Nginx is a full web server.

hypnotist• 14 years ago

I think Lua/nginx and ATS are quite different beasts, solving different problems. Nice presentation on ATS - "Apache Traffic Server: More Than Just a Proxy" https://www.usenix.org/conference/lisa11/apache-traffic-serv...

mattdeboard4• 14 years ago

I've written an authorization server for CloudFront using Python/Flask and have wondered whether just writing the same functionality via Lua could be a better/faster replacement. I'm just not clear on how to use Lua to make the calls to our API. This is a good pointer in the right direction though.

mtourne2• 14 years ago

Nginx exposes multiple phase to process an incoming HTTP Request. Mainly rewrite, access, content, header_filter, and log

You can embed Lua at the access phase, and query your API from there. Some of the Lua libraries of the OpenResty package [1] might help you do that.

And here [2] you can find an example of OAuth support.

[1] http://openresty.org/#Components [2] http://seatgeek.com/blog/dev/oauth-support-for-nginx-with-lu...

justincormack2• 14 years ago

Here is some example auth code for Amazon services in Lua for Nginx I wrote ages ago, which might help get an idea of what the code might look like https://gist.github.com/948423

It is very fast doing that type of stuff in Lua, and it all gets done in the same request context.

There is some new functionality in openresty since that example, so there are probably other choices of ways to implement it.

tferris2• 14 years ago

Sounds amazing and would love to step in immediately. Have some basic questions after reading briefly the post and the comments here.

1) What's the difference between OpenResty and the Nginx+Lua module (is the module the core of OpenResty)?

2) How does it compare to Node regarding ecosystem, performance and every day usage/maintainability (if it's comparable)?

jhancock• 14 years ago

I've only been playing with openresty for a couple of months. Here's what I've learned:

1 - openresty is nginx and many official and unofficial modules. From what I've asked the experts, there is supposed to be no difference in the source; openresty is just a single package of many modules with an easy to use ./config and make process.

2 - The nginx module and lua lib ecosystem seems to have most of the basics in order to roll a high level app framework, but only a half baked one exists thus far: https://github.com/appwilldev/moochine Also: https://github.com/antono/valum https://github.com/pintsized/lua-resty-rack

My impression is if you have the time to roll your own sinatra-like framework, it should be pretty straightforward.

tferris2• 14 years ago

Thanks!

decktech• 14 years ago

I've been using Openresty (with Lua and Redis support) to collect a large amount of data from GET requests for a video sharing site. Having nginx push data directly into Redis is super fast, lends easily to real-time metrics, and makes it easy to batch everything up and push it into MySQL at the end of the day. Now that Redis supports internal Lua scripts, you can also do custom atomic functions and other neat things.

If you can get around the Redis SPOF, OpenResty + Redis is great for large-volume data collection. Thousands of requests/sec on an EC2 Small at < 10% load.

Pushing Nginx to its limit with Lua

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