Varnish @ Opera

Varnish Users Group MeetingParis, 22nd March 2012

Cosimo Streppone <cosimo@opera.com>

• October 2009• 1 old recycled machine, 2 Gb of disk allocated• Started serving static pictures (1M+ req/day)• Then more...• Even more...• ...• ~15% of all My Opera requests were «varnished»• Around 8M req/day

1st Varnish deployment: My Opera

• Still using Debian EtchFirst Varnish instance was running v1.x from Etch.several years old, not good

• Experienced VIPs– ”Very Interesting Problems”– User X getting User Y's session– Random users getting admin powers. Nightmare!

• Theory: Varnish was caching response bodies that containedSet-Cookie: opera_session=<session_id>

My Opera – The start

if (req.url ~ "^/community/users/avatar\.pl/[0-9]+$"

|| req.url ~ "^/.+/avatar\.pl$"

|| req.url ~ "^/.+/picture\.pl\?xscale=100$"

|| req.url ~ "^/desktopteam/xml/atom/blog/?$"

|| req.url ~ "^/desktopteam/xml/rss/blog/?$"

|| req.url ~ "^/community/api/users/friends\.pl\?user=.+$"

|| req.url ~ "^/community/api/users/groups\.pl\?user=.+$"

) {

unset req.http.Cookie;

unset req.http.Authorization;

lookup;

}

My Opera – The start

...

# Check for cookie only after always-cache URLs

if (req.http.Cookie ~ "(opera_session|opera_persistent_)") {

pass;

}

# DANGER, Will Robinson! Caching the front-page

# At this point, lots of Google Analytics cookies will go in.

# No problem. It's stuff used by Javascript

if (req.url ~ "^/community/$") {

lookup;

}

pass;

}

My Opera – Pass logged in users

My Opera: testing Varnish setup

...ok 289 - Got response from backend for /community/ (from ...) ok 290 - Correct status line# Adding header [Cookie] => [language=it]# ----------# GET http://cache01.my.opera.com:6081/community/# Host: my.opera.com# ------------ok 291 - 2nd request: got response from backend for /community/ (from...)ok 292 - Correct status line# X-Varnish: 1211283813 1211283812# X-Varnish-Status: hit# X-Varnish-Cacheable: yes, language cookie# X-Varnish-URL: /community/ok 293 - URL '/community/' was handled correctly by varnish# cookie_header:ok 294 - URL '/community/' has correct cookies (or no cookies)1..294

All tests successful.

X-Varnish: 1211283813 1211283812X-Varnish-Status: hitX-Varnish-Cacheable: yes, language cookieX-Varnish-URL: /community/

My Opera – Next steps

My Opera – Next steps

● Front page caching● Static assets and UGC● On-the-fly thumbnails● “Shields-up” configuration

Problem

• Very dynamic, i18n• Accept-Language

header variation• Vary: Accept-Language sub-optimal

Front page caching

Solution

• varnish-accept-language “extension”

Client sends

Accept-Language: ru, uk;q=0.9

Accept-Language: es-ES, es;q=0.8

Accept-Language: fr, it;q=0.7

Accept-Language: fr

Front page caching - Accept-Language

Backend receives

Accept-Language: ru

Accept-Language: es

Accept-Language: it

Accept-Language: ben

SUPPORTED_LANGUAGES = “:de:es:it:ru:”DEFAULT_LANGUAGE = “en”

Front page caching

Problem

• One central location• SPOF• High latency US -> NO

Static assets and UGC servers

Solution

• Decentralized varnish servers in multiple DC

• Talking to 1 backend• Very long TTL• Health probes• Cache invalidation API• Built our GeoDNS

Problem

• Change of Design™ made our millions of pre-generated thumbnails useless

Thumbnail generation and caching

Solution

• Switch to on-the-fly generation model

• Used mod_dims (AOL)• Varnish on :80• 2 backends

300k objects95% hit rate avg800 req/s/backend peak

Thumbnail generation and caching

How it works

http://localhost/dims/ crop/472x360/ contrast/+1/ quality/90/ /actual/picture/url.jpg (remote too!)

Using rewrite rules

Http://localhost/tn/small/ /actual/picture/url.jpg

Thumbnail generation and caching

● Recognize mobile/non-mobile

● Scale thumbnails on the fly

● Reduce JPEG quality Ex.: /thumb/small/quality/80/some/path/pic.jpg

Problem

• Original setup too specific to My Opera

• Long tail of non-popular content “unprotected”

• Can we find some more generic setup?

Shields-up configuration

Solution

• DDoS• Varnish in front, rather

than after frontends• Cache most logged out

requests with lower TTL• Compromise solution,

but generic enough

Sitecheck

• Used by the Opera browser• Must work! Failure not an option• ~8k req/s/backend peak• 2 varnish boxes, 16k req/s, 20k peak• 85% hit rate• TTL 10'

Sitecheck – Malware, fraud protection

Opera TV Store

Country-level ban

• Contract mandates that TV Store shouldn't be available in specific countries

• Country check in the backend means no caching is possible

• Implemented with varnish-geoip

Country-level bansub country_ban_list_check {

# Allow testing of country ban if (req.http.Cookie ~ "x_geo_ip_forced\s*=\s*country:..") { set req.http.X-Geo-IP = regsuball( req.http.Cookie, "^.*x_geo_ip_forced\s*=\s*(country:..).*$", "\1" ); log "Forced X-Geo-IP to '" req.http.X-Geo-IP "'"; }

# Block access to tvstore in these countries if (req.http.X-Geo-IP && req.http.X-Geo-IP ~ "^country:(C1|C2|C3|...)$") { log "Country ban"; error 750 "tvstore is not available in your country"; }}

sub vcl_recv { C{ vcl_geoip_country_set_header_xff(sp); }C call country_ban_list_check;}

Brand + device TV detection

• Analyze User-Agent header

• Regex the hell out of it

• Send X-Brand, X-Device header to backend

• Fallback Device detection in the backend(for development, test setups, ...)

VCL library

accept-encoding.vcl

# STD: Deal with different Accept-Encoding formatssub accept_encoding_normalize {

if (req.http.Accept-Encoding) {

if (req.http.Accept-Encoding ~ "gzip") { set req.http.Accept-Encoding = "gzip"; }

elsif (req.http.Accept-Encoding ~ "deflate") { set req.http.Accept-Encoding = "deflate"; }

else { unset req.http.Accept-Encoding; }

}}

accept-language.vclC{

/* * Accept-language header normalization * * - Parses client Accept-Language HTTP header * - Tries to find the best match with the supported languages * - Writes the best match as req.http.X-Varnish-Accept-Language * * http://github.com/cosimo/varnish-accept-language */

#include <ctype.h> /* isupper */#include <stdio.h>#include <stdlib.h> /* qsort */#include <string.h>

#define DEFAULT_LANGUAGE "en"#define SUPPORTED_LANGUAGES ":de:en:es-la:fr:fy:hu:ja:no:pl:pt-br:ru:sk:sq:sr:tr:uk:vn:xx-lol:zh-tw:"

…

maintenance.vcl + {up,down}.shinclude "/etc/varnish/accept-encoding.vcl";

backend oopsy { .host = "10.20.21.22”; .port = "80";}

sub vcl_recv {

set req.backend = oopsy;

# Serve page from within Varnish. See vcl_error() if (req.url == "/ping.html") { error 700; }

call accept_encoding_normalize;

# Collapse URLs, so that we have just one cached object set req.url = "/maintenance-down";

remove req.http.Cookie; remove req.http.Authorization; return (lookup);}

purge.vclacl purge { … }

sub vcl_recv {

if (req.request == "PURGE") { If (! (client.ip ~ purge)) { error 405 "Not allowed."; } purge("req.url == " req.url); error 200 "Purged."; }

else if (req.request == "PURGE_SUFFIX") { set req.http.X-URL = regsuball(req.url, "\[|\]|[\\^.$|()*+?{}]", "\\\0") "$"; purge_url(req.http.X-URL); unset req.http.X-URL; error 200 "Purged suffix."; }

else if (req.request == "PURGE_PREFIX") { … }

}

Ugly!

X-forwarded-for.vcl

# See http://www.varnish-cache.org/trac/ticket/540sub inject_forwarded_for {

# Rename the incoming XFF header to work around a Varnish bug if (req.http.X-Forwarded-For) { # Append the client IP set req.http.X-Real-Forwarded-For = req.http.X-Forwarded-For ", " regsub(client.ip, ":.*", ""); } else { # Simply use the client IP set req.http.X-Real-Forwarded-For = regsub(client.ip, ":.*", ""); }}

Wat!?

Testing VCLs – http-cuke

http-cuke – csrf.test

Feature: TVStore uses cookies to protect against CSRF attacks

In order to protect the users from CSRF attacks As a TV Store developer I want to verify that some pages send out a CSRF cookie token to the browser or device

Scenario: Accessing the Backgammon application URL

Given a "Opera/9.80 (Linux … Opera TV Store)" user agent When I go to "https://tvstore.server/store/app/backgammon" Then the final HTTP status code should be "200" Then the page should contain "A board game for one player"

Then the page should not be cached by varnish

Then the server should send a CSRF token

http-cuke – prove-like output

$ http-cuke --test ./csrf.test

$ http-cuke --test-dir ./some-dir

http-cuke – a sample test run

# ============================================================# FEATURE: TV Store uses cookies to protect against CSRF attacks# ============================================================# ------------------------------------------------------------# SCENARIO: Accessing the Backgammon application URL# ------------------------------------------------------------ok 1 - Given a "Opera/9.80 (Linux...)" user agentok 2 - When I go to "https://tvstore.server/app/backgammon"ok 3 - Status code is 200 (expected 200)ok 4 - Then the final HTTP status code should be "200"ok 5 - String 'A board game for one player' was found in the pageok 6 - Then the page should contain "A board game for one player"ok 7 - X-Varnish header contains only current XID (523289525)ok 8 - Age of cached resource is zerook 9 - Then the page should not be cached by varnishok 10 - CSRF token was found (49a0da1b2758bf62a028072e4f7f36dc)ok 11 - Then the server should send a CSRF token

Puppet module

varnish/manifests/init.pp

class varnish {

package { "varnish": ensure => "installed" }

file { "/etc/init.d/varnish": … }

file { "/etc/sysctl.conf": … } exec { "update-sysctl": … }

file { "/usr/share/varnish/purge-cache": … }

service { "varnish": ensure => "running", … }

munin::plugin::custom { "varnish_": } munin::plugin { [ "varnish_backend_traffic", "varnish_expunge", … }}

Custom init script

# Lower stack limit demand for every Varnish thread# http://projects.linpro.no/pipermail/varnish-misc/2009-August/002977.html# Still relevant for Varnish 3 ??ulimit -s 256

# Startup with custom cc_command fails# Filed Debian bug #659005if bash -c "start-stop-daemon \ --start --quiet --pidfile ${PIDFILE} \ --exec ${DAEMON} -- -P ${PIDFILE} \ ${DAEMON_OPTS} > ${output} 2>&1"; then log_end_msg 0else …

Custom sysctl settings

# From http://varnish.projects.linpro.no/wiki/Performance# + our own tweaking and tuning

net.ipv4.ip_local_port_range = 1024 65536net.core.rmem_max = 16777216net.core.wmem_max = 16777216net.ipv4.tcp_rmem = 4096 87380 16777216net.ipv4.tcp_wmem = 4096 65536 16777216net.ipv4.tcp_fin_timeout = 30net.core.netdev_max_backlog = 30000net.ipv4.tcp_no_metrics_save = 1net.core.somaxconn = 262144net.ipv4.tcp_syncookies = 1net.ipv4.tcp_max_orphans = 262144net.ipv4.tcp_max_syn_backlog = 262144net.ipv4.tcp_synack_retries = 2net.ipv4.tcp_syn_retries = 2

Purge cache script

Modeled after Debian vcl-reload script

$ purge-cache -a$ purge-cache -u http://some.url$ purge-cache -r '^/(home|user)/'

varnish/manifests/init.pp – 2define varnish::config ( $vcl_conf="default.vcl", $listen_address="", $listen_port=6081, $thread_min=400, $thread_max=5000, $thread_timeout=30, $storage_type="malloc", $storage_size="12G", $ttl=60, $thread_pools=$processorcount, $sess_workspace=131072, $cc_command="", $sess_timeout=3 ) {

file { "/etc/default/varnish": ensure => "present", owner => "root", group => "root", mode => 644, content => template("varnish/debian-defaults.erb"), require => Package["varnish"], notify => Service["varnish"], }

}

Example of varnish::config

varnish::config { "cache-varnish-config": vcl_conf => "cache.vcl", storage_type => "malloc", storage_size => "20G", listen_port => 80, sess_workspace => 131072, ttl => 86400, thread_pools => 8, thread_min => 800, thread_max => 10000, # Necessary for GeoIP cc_command => 'exec cc -fpic -shared -Wl,-x \ -L/usr/include/GeoIP.h -lGeoIP -o %o %s',}

varnish/manifests/init.pp – 3

define varnish::vcl ($source) {

file { "/etc/varnish/${name}.vcl": ensure => "present", owner => "root", group => "root", mode => 644, source => $source, require => Package["varnish"], notify => Service["varnish"], }

}

Migration to Varnish 3

Following Debian stableNot there yet. Still anchored to 2.1

Migration 2.0 2.1 was relatively painless→

Embedded C code?Migrate accept-language and geoip

extensions to VMODs

2.1 3.0 syntax changes?→Test our VCLs

CustomizationsAre they still relevant for 3.0?

(ulimit -s 256, etc...)

I'd like to see in varnish...

Easier VMODsIdeally, as easy as embedded C!

varnishtop -t10s

Collect traffic for 10s and then report

Bonus feature: tags, AKA group-by

varnishtop -i RxURL -g RxHeader.Referer -t 60s

Use headers as vars less than ideal

Introduce variables or registers to avoid

set req.http.X-Var = regsuball( req.http.Some-Header, '…', '\1');

Better Cookies inspectionAvoid regsuball() mess on req.http.Cookie

set req.http.Cookie.SomeName = “xxx”;set req.http.X-Var1 = req.http.Cookie.sessionid;

and...

set var.SessionID = req.http.Cookie.sessionid;

file storage?malloc works fine for us, but we always had

problems with file storage

Better SSL handlingNot really. nginx works fine.

Questions!

opera.com/jobs