Varnish Cache 5.0

http://varnish.org/releases/rel5.0.0.html#rel5-0-0

by ruben_varnish • 10 years ago

163 53 10 years ago

boyter2• 10 years ago

From the release notes http://varnish.org/docs/5.0/whats-new/relnote-5.0.html "It is important that people understand that Free and Open Source Software isn't the same as gratis software: Somebody has to pay the developers mortgages and student loans."

Varnish is an excellent piece of software, but I thought it was totally funded by the commercial side varnish software. How does this model work? It seems odd to ask for donations while also selling an expensive supported version?

qeternity• 10 years ago

"Until now Varnish Software has done a lot of work for the Varnish Cache project, but for totally valid reasons, they are scaling that back and the project either needs to pick up the slack or drop some of those activities."

Why they are pulling back is anybody's guess. But it sounds like they are focusing on monetizing the existing codebase instead of further developing it.

phkamp4• 10 years ago

Varnish Cache Author here.

The Varnish Cache FOSS project and Varnish Software the company are two entirely different things.

By and large, the Varnish Cache FOSS project is me, and I am not employed by Varnish Software: I have my own one-man company where I "make computers to do weird things".

The time I spend on Varnish Cache is funded by "The Varnish Moral License":

http://phk.freebsd.dk/VML/index.html

Varnish Software is one of the handful of companies who pay via the VML to keep me working on Varnish.

Varnish Software has also supported the project in many other ways as well, from running the project server to donating manpower and source code.

Some of these things are being scaled down, for instance the project server had become the square peg in their round internal IT systems, so I have been migrating that off to a server kindly sponsored by RootBSD.

boyter2• 10 years ago

Thanks so much for replying. I did notice the Moral License and was confused as to how it works. I will attempt to get some high profile users I know to help pay for some continued development.

tomschlick2• 10 years ago

As someone who has never used Varnish but has used Nginx's cache to some degree... whats the benefit of placing varnish in the middle vs going with Nginx?

corecoder• 10 years ago

A one or two orders of magnitude greater speed, lots of configurations for caching policies, the ability to split a request in several subrequests (ESI) and some other nice things.

omn12• 10 years ago

Not sure if the performance gains are still valid. There's reports that state the contrary: https://deliciousbrains.com/page-caching-varnish-vs-nginx-fa... Nginx has something similar to ESI called SSI (http://serverfault.com/questions/406103/main-differences-bet...)

jacquesm• 10 years ago

Faster and far more configurable, the configuration language (VCL) compiles to 'C' and you can inline bits of C if you want.

https://www.varnish-cache.org/trac/wiki/ArchitectureInlineC

zepolen• 10 years ago

Faster in theory maybe. In production nginx has always faster, more stable, less resources. I've used both extensively. Varnish has more caching features and configuration for sure.

zcam2• 10 years ago

If you use it for caching, nginx is lacking something quite important at the moment: stale-while-revalidate (https://tools.ietf.org/html/rfc5861)

Aka serving a cached response while the cache is getting refreshed (even to the request who initiated the refresh). Currently when nginx has to refresh the cache it will "hang" the current response until it gets refreshed (the requests that follow, even while the cache is getting refreshed, will get the stale version tho).

It's the difference between your client being amazed by how fast your api is, to "wtf does page X takes 3s to render from time to time" comments.

e98cuenc• 10 years ago

I think "proxy_cache_use_stale updating;" covers this case

justincormack• 10 years ago

There is an openresty project that provides this https://github.com/pintsized/ledge - also provides ESI and more.

buro9• 10 years ago

* ESI support is really nice (if you're an API designer, you can really go nuts on this and make a super simple API do some very complex things or expressive composition from lots of simple calls)

* More fine-grained control of your caching is possible

* Easier to express normalisation of requests (increase your cache hit rate and protect your underlying origin from malicious requests by discarding cache busters)

* Inline C means you can do things like move your authentication to the edge

* In theory if you have enough RAM you can go faster than nginx's on-disk... in practice the sweet spot for the gain is small and they're both on par

But then... it comes with disadvantages too. Like most Varnish services would never let you do the nice Inline C stuff because no-one in their right mind would run untrusted code in their environment where it could impact another customer. If you see a provider do this (at any price point), avoid them.

ruben_varnish4• 10 years ago

Since 3.0 you have VMODs, to counter for the well-founded lack of Inline C support around. These Varnish modules will extend VCL with C, C++ or even Rust libraries on a safer manner: https://varnish-cache.org/vmods/

If you make your own VMOD(can take from a few hours to days), make sure to send a PR and add it to the directory above (IOW: share it) :)

tomschlick2• 10 years ago

Thanks for the detailed list! ESI looks pretty sweet so I'll have to take a look at that as we scale out our API in the coming months.

jimjag3• 10 years ago

"In theory if you have enough RAM you can go faster than nginx's on-disk... in practice the sweet spot for the gain is small and they're both on par"

Not in theory, but in reality. Even if you don't, varnish's file on-disk implementation is just as good as nginx's if not better.

The idea behind a cache is to increase performance. If that is the priority then you would pick a design and implementation geared towards that problem set. Sure you can say "Well, nginx or httpd is 'good enough'" and that would be right. But when nginx or httpd aren't good enough, you need varnish. And even when you don't need varnish, it is often a better architectural design to break out specific functionality (best of breed).

c0l0• 10 years ago

Take a look at `varnishlog` while you have traffic flowing thru - you'll feel like you've seen the light :) Also, read the vsl-query docs: https://www.varnish-cache.org/docs/trunk/reference/vsl-query...

In terms of introspectability, Varnish (afaik) is without equal.

ruben_varnish4• 10 years ago

Totally agreed!

I believe that the power and utility of VSL are so underestimated and overlooked that I don't know where to start...

sdca• 10 years ago

The ability to manually purge the cache by URL, with wildcards, is pretty handy.

mwpmaybe• 10 years ago

If you're already using Nginx and its caching subsystem is working for your use case(s), then I wouldn't worry about it. A typical web stack is composed of load balancing, SSL termination, caching and compression, and static and dynamic content serving. Nginx is capable of all these things (including dynamic content serving using OpenResty).

Once you start breaking your stack apart to 1) add redundancy, 2) isolate hardware for different workloads, and 3) scale the components independently of each other, the situation gets a little more interesting. Sure, you could run different clusters of Nginx for each of SSL termination, static content, cache and compress, etc. and have them reverse proxy to each other (and some people probably do this), but when you get to this evolution of your architecture, it's worth evaluating the different options for each layer of the stack. There's an argument to be made that e.g. HAProxy is a better load balancer, Nginx is a better static content server, Pound is a better SSL terminator, Varnish is a better caching and compressing reverse proxy, etc. (N.B. that I am not saying these things, I am just saying that they can be said.) If you're not serving static content at all—let's say you're presenting an API written in Elixir/Phoenix—it may not make sense to go with Nginx in the first place!

Regarding Varnish, specifically, I've found that it offers unparalleled power and flexibility when it comes to caching and compression. Yes, that power and flexibility comes at the cost of more complexity, but it's there when you need it. It offers different storage backends, including a pure memory backend; the ability to serve gzipped content directly from cache (for supported clients); PURGE and BAN HTTP verbs; synthetic responses; query string sorting; the ability to serve stale content while updating; ESI; and probably a whole bunch of other stuff I'm forgetting and/or have never used. Nginx and Nginx Plus may support some or all of these things, built-in or as modules... I'm not sure.

jimjag3• 10 years ago

1: Performance. varnish provides much less latency.

2: More control.

3: Better compliance

willvarfar2• 10 years ago

Historically, PHK was a very vocal criticizer of SPDY and HTTP/2: http://www.varnish-cache.org/docs/trunk/phk/http20.html

Of course he relented and implemented SPDY and HTTP/2 anyway.

But all the same I can't help but feel that his original criticsm still stands, and what we need is a rethink of e.g. cookies.

youngtaff• 10 years ago

The original brief for H2 was to have the same semantics etc, as HTTP/1.x

From my reading PHK didn't think it went far enough, and wanted to change more.

I think he's got good points to make on session ids, cookies etc. and I suspect we'll se some of the ideas feed into future versions too.

willvarfar2• 10 years ago

I don't think we will, because most in the driving seat make their money identifying visitors. Cynical but true.

jjoe• 10 years ago

It's always good to see new stuff coming out for Varnish. Do these changes warrant a major jump in release numbers especially when HTTP/2 support (biggest feature) is experimental?

Anyway, I'm looking forward to testing it out and integrating v5 with Cachoid ( shameful plug: https://www.cachoid.com/ ).

ksherlock• 10 years ago

From the horse's mouth:

Varnish 5.0 changes some (mostly) internal APIs and adds some major new features over Varnish 4.1.
We are in the process of adding HTTP/2 support to Varnish ... we hope to have it production ready for the next major release (2017-03-15).

hannob• 10 years ago

Do I understand this right? It supports HTTP/2, but doesn't support HTTPS. Therefore it supports HTTP/2 in a mostly unusable form, because browser vendors (for good reasons) decided to support HTTP/2 only over HTTPS.

ruben_varnish4• 10 years ago

Yes, Varnish does h2c so for HTTPS you will need something like 1.4 or later: https://hitch-tls.org/

Made by Varnish Software to provide a "browser-vendor-compliant" HTTP/2 stack.

jamwt• 10 years ago

Hmm... you guys sure have pretty thoroughly sanitized all references to Stud at this point in code, documentation, READMEs, etc.

:-(

vertex-four• 10 years ago

You could put a TLS proxy in front of it, I think? Though you'd have to implement ALPN or NPN in the proxy. (Apparently Hitch, above, does.)

phkamp4• 10 years ago

The reason I don't want to link Varnish against a SSL library, is that in my considered opinion, they all suck.

From a purely operational point of view, you are better of with two different SSL proxies in front if your Varnish (or other webserver), so that you can turn OpenSSL off in even-numbered weeks and the other (pick your poison) in odd-numbered weeks.

The code to hold safely onto your certificate and do all the songs and dances involved in SSL/TLS, is under all circumstances something which should be isolated in as small a process/protection domain as possible.

encoderer• 10 years ago

This is why i love hn. Thanks for answering this!

convolvatron• 10 years ago

they do. they really do. i've read your screed about this and i completely agree. absolutely appalling. in particular a marked inability to handle thread concurrency, which is pretty fatal to varnish.

however. given that tls is operationally important. and using an additional proxy causes a lot of configuration and performance headaches. isn't there any better path forward?

flojo• 10 years ago

https://www.nginx.com/blog/maximizing-drupal-8-performance-n...

In the BBC’s testing, they found that with NGINX as a drop-in replacement for Varnish, they saw five times more throughput.

phkamp4• 10 years ago

I don't suppose that particular workload was very suited for Varnish in the first place, if you read carefully, you'll soon realize that most people don't have that kind of content.

I have heard from (other parts of) BBC that Varnish saved a fair amount of bacon for them during the London Olympics, obviously in different workloads.

And nobody would be more surprised than me, if Varnish was a micacle-cure for every single website in the world...

cheald• 10 years ago

nginx as a cache is very minimal-featured compared to Varnish. If it fits your workload, great. If not, Varnish is an exceptional tool.

olavgg• 10 years ago

PHK explained the cause of this is that the Linux kernel VM system performs poorly when overcomitted.

https://news.ycombinator.com/item?id=10752209

So the conclusion is, as long your malloc fits in your system memory, Varnish should be blazing fast on Linux. If you need a gigantic cache, please try FreeBSD.

Varnish Cache 5.0

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