varnish, the high performance valhalla?

Kings of Code 2011

Varnish, the high performance valhalla?

∂ Open source addict

JEROEN VAN DIJK

∂ CTO @ Enrise∂ Email : [email protected]∂ Twitter: @neorey

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mailto:[email protected]

mailto:[email protected]

THE ENRISE RESTAURANT

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∂ We want to prepare the best dishes

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∂ We want to prepare the best dishes∂ With the best ingredients

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∂ Engineers are our top chefs!


∂ We want to prepare the best dishes∂ With the best ingredients∂ To create a magical client experience!

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BEFORE WE START

WHO KNOWS RFC 2616?

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BEFORE WE START

WHO KNOWS HTTP?

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BEFORE WE START

WHO THINKS HE/SHE KNOWS

HTTP?

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∂ Wikipedia : Proxy

STANDARD PROXY

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∂ Wikipedia : Reverse proxy

REVERSE PROXY

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∂ Wikipedia : Reverse proxy

REVERSE PROXIES

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∂ NOT a webserver!

WHAT IS VARNISH? (1)

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∂Caching reverse proxy

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∂Caching reverse proxy∂Load balancer

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∂Caching reverse proxy∂Load balancer∂Fail over system

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∂Caching reverse proxy∂Load balancer∂Fail over system∂HTTP Accelerator

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∂ Originally built for a Norwegian newspaper

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∂ Originally built for a Norwegian newspaper∂ > 545k new hostnames in December 2010§NetCraft monthly survey

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∂ Massive growth in usage


∂ Originally built for a Norwegian newspaper∂ > 545k new hostnames in December 2010§NetCraft monthly survey

∂ Known users§Wikileaks§Facebook§Twitter§SlashDot

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∂ Scaling limitations currently unknown


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∂Designed for 64bit architecture

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∂Designed for 64bit architecture∂Highly scalable

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∂Designed for 64bit architecture∂Highly scalable§Varnish in front of Varnish(es)

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∂Designed for 64bit architecture∂Highly scalable§Varnish in front of Varnish(es)∂Perfect browser cache solution

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∂Designed for 64bit architecture∂Highly scalable§Varnish in front of Varnish(es)∂Perfect browser cache solution§Prevent those hard refresh calls!

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∂ Possible request paths

INTERNALS (1)

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∂ Optimal request path

INTERNALS (2)

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∂ Caching request path

INTERNALS (3)

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∂ Prevent caching

INTERNALS (4)

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∂ Bypassing Varnish

INTERNALS (5)

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∂ Errors or issueing restarts

INTERNALS (6)

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∂ Compiled to C when run

VARNISH CONFIGURATION LANGUAGE (1)

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∂ 11 subroutines (vcl_recv, vcl_hash, etc ...)

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∂ 11 subroutines (vcl_recv, vcl_hash, etc ...)∂ Backend(s)

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∂ 11 subroutines (vcl_recv, vcl_hash, etc ...)∂ Backend(s)∂ Directors (random, round robin, hash)

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∂ 11 subroutines (vcl_recv, vcl_hash, etc ...)∂ Backend(s)∂ Directors (random, round robin, hash)∂ Access control lists

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∂ 11 subroutines (vcl_recv, vcl_hash, etc ...)∂ Backend(s)∂ Directors (random, round robin, hash)∂ Access control lists∂ Saint and grace mode

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∂ 11 subroutines (vcl_recv, vcl_hash, etc ...)∂ Backend(s)∂ Directors (random, round robin, hash)∂ Access control lists∂ Saint and grace mode∂ Custom subroutines

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∂ 11 subroutines (vcl_recv, vcl_hash, etc ...)∂ Backend(s)∂ Directors (random, round robin, hash)∂ Access control lists∂ Saint and grace mode∂ Custom subroutines∂ Inline C

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∂ 11 subroutines (vcl_recv, vcl_hash, etc ...)∂ Backend(s)∂ Directors (random, round robin, hash)∂ Access control lists∂ Saint and grace mode∂ Custom subroutines∂ Inline C∂ Since v3.0 : VMODS

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∂ Cache images in vcl_recv


if (req.request == “GET” &&req.url ~ “\.(gif|jpg|jpeg|bmp|png|ico)$”) {unset req.http.cookie;set req.grace = 1m;return(lookup);

}

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∂ Remove Google Analytics in vcl_recv


if (req.http.cookie) { set req.http.Cookie = regsuball(req.http.Cookie,

"__utm.=[^;]+(; )?", ""); if (req.http.cookie ~ "^ *$") { remove req.http.cookie; }}

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∂ Multiple backend configuration


backend default { .host="192.168.1.10"; .port="8080"; .probe={ .url=”/test.php”; }}backend second { .host="192.168.1.20"; .port="8080";}

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∂ Load balanced 33 / 66 % config


director balance random { { .backend = default; .weight = 1; } { .backend = second; .weight = 2; }}sub vcl_recv { set.req.backend = balance; return(pass);}

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∂ Adding headers on response


if (obj.hits > 0) { #if hit add hit count set resp.http.X-Cache = "HIT-" obj.hits;} else { set resp.http.X-Cache = "MISS”;}

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VARNISHING WORDPRESS (1)

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∂Siege on standard WordPress homepage

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∂Siege on standard WordPress homepage§No Varnish

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∂Siege on standard WordPress homepage§No Varnish§Default Varnish installation

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∂Siege on standard WordPress homepage§No Varnish§Default Varnish installation§Custom VCL configuration

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∂ No Varnish


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∂ Default Varnish


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∂ Kill those cookies!!


# Drop any cookies sent to WordPress.sub vcl_recv { unset req.http.cookie;}# Drop any cookies WordPress tries to send backsub vcl_fetch { unset beresp.http.set-cookie;}

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∂ Custom Varnish


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OTHER PITFALLS

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OTHER PITFALLS

∂ Accept headers§application/vnd.kingsofcode.speakers+xml;§return “Vary: Accept” header

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OTHER PITFALLS

∂ Accept headers§application/vnd.kingsofcode.speakers+xml;§return “Vary: Accept” header∂ Accept-encoding header

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∂ Not specifically Varnish issues

OTHER PITFALLS

∂ Accept headers§application/vnd.kingsofcode.speakers+xml;§return “Vary: Accept” header∂ Accept-encoding header∂ Vary: User-Agent header

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∂ Very powerful for content assembly

EDGE SIDE INCLUDES (1)

∂Markup language∂Co-authored Akamai, IBM, Oracle & more∂Extensive features

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∂ Examples? http://esi-examples.akamai.com


∂ if ... else§<esi:choose><esi:when> ... <esi:otherwise>

∂ Variables§<esi:assign> and <esi:vars>

∂ Varnish implements only one feature!§<esi:include src=”uri” />

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http://esi-examples.akamai.com

http://esi-examples.akamai.com

∂ VCL config for ESI


if (req.url ~ "^/url/to/esi/snippets") { unset beresp.http.set-cookie;}## enable esi on header from backendif (beresp.http.enable-esi == "1") { set beresp.do_esi = true; //varnish 3.0

unset beresp.http.enable-esi;}

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∂ Where are the ESI’s?


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∂ Different TTL’s for content snippets


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∂ You can’t go without

TOOLS

∂Varnishstat∂Varnishsizes∂Varnishtop∂Varnishadm∂Varnishlog

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VARNISHLOG

∂ Log hits§varnishlog -o VCL_Call hit | grep RxURL∂ Log misses§varnishlog -i TxURL

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∂ Request of a gif image by client

VARNISHLOG

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CAVEATS

∂ Unsuitable for 32 bit

∂ Beware of cookie monster applications

∂ Check your API design

∂ Avoid large files

∂ Minimize cookie usage in ESI

∂ No SSL support

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∂ Questions? Thank you!