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Varnish 4 documentation & VCL #8

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Feb 15, 2017
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Varnish 4 documentation & VCL #8

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16 changes: 16 additions & 0 deletions docs/varnish/varnish.md
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eZ Platform Varnish configuration
=================================

Prerequisites
-------------
* A working Varnish 4.1 and higher setup with xkey module installed.

Recommended VCL base files
--------------------------
For Varnish to work properly with eZ, you'll need to use the provided configuration:

* [eZ Platform optimized Varnish VCL](vcl/varnish4.vcl)

> **Note:** Http cache management is done with the help of [FOSHttpCacheBundle](http://foshttpcachebundle.readthedocs.org/).
One may need to tweak their VCL further on according to [FOSHttpCache documentation](http://foshttpcache.readthedocs.org/en/latest/varnish-configuration.html)
in order to use features supported by it.
267 changes: 267 additions & 0 deletions docs/varnish/vcl/varnish4.vcl
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// Varnish VCL for:
// - Varnish 4.1 or higher with xkey vmod (via varnish-modules package, or via Varnish Plus)
// - eZ Platform 1.8 or higher (configured for Varnish, incl with Symfony HttpCache Proxy disabled)
//
// Complete VCL example, further reading on:
// - https://symfony.com/doc/current/http_cache/varnish.html
// - https://foshttpcache.readthedocs.io/en/stable/varnish-configuration.html
// - https://github.com/varnish/varnish-modules/blob/master/docs/vmod_xkey.rst
// - https://www.varnish-cache.org/docs/trunk/users-guide/vcl.html
//
// Make sure to at least adjust default domain/ip values on backend, invalidators & debuggers, current values are set
// for default bundled docker containers for testing use and needs to reflect your setup instead.

vcl 4.0;
import std;
import xkey;

// Our Backend - Assuming that web server is listening on port 80
// Replace the host to fit your setup
backend ezplatform {
.host = "web";
.port = "80";
}

// ACL for invalidators IP
acl invalidators {
"127.0.0.1";
"172.16.0.0"/20;
"app";
}

// ACL for debuggers IP
acl debuggers {
"127.0.0.1";
"172.16.0.0"/20;
}

// Called at the beginning of a request, after the complete request has been received
sub vcl_recv {

// Set the backend
set req.backend_hint = ezplatform;

// Advertise Symfony for ESI support
set req.http.Surrogate-Capability = "abc=ESI/1.0";

// Varnish, in its default configuration, sends the X-Forwarded-For header but does not filter out Forwarded header
unset req.http.Forwarded;

// Trigger cache purge if needed
call ez_purge;

// Don't cache requests other than GET and HEAD.
if (req.method != "GET" && req.method != "HEAD") {
return (pass);
}

// Don't cache Authenticate & Authorization
// You may remove this when using REST API with basic auth.
if (req.http.Authenticate || req.http.Authorization) {
if (client.ip ~ debuggers) {
set req.http.X-Debug = "Not Cached according to configuration (Authorization)";
}
return (hash);
}

// Do a standard lookup on assets (these don't vary by user context hash)
// Note that file extension list below is not extensive, so consider completing it to fit your needs.
if (req.url ~ "\.(css|js|gif|jpe?g|bmp|png|tiff?|ico|img|tga|wmf|svg|swf|ico|mp3|mp4|m4a|ogg|mov|avi|wmv|zip|gz|pdf|ttf|eot|wof)$") {
return (hash);
}

// Retrieve client user context hash and add it to the forwarded request.
call ez_user_context_hash;

// If it passes all these tests, do a lookup anyway.
return (hash);
}

// Called when a cache lookup is successful. The object being hit may be stale: It can have a zero or negative ttl with only grace or keep time left.
sub vcl_hit {
if (obj.ttl >= 0s) {
// A pure unadultered hit, deliver it
return (deliver);
}

if (obj.ttl + obj.grace > 0s) {
// Object is in grace, logic below in this block is what differs from default:
// https://varnish-cache.org/docs/5.0/users-guide/vcl-grace.html#grace-mode
if (!std.healthy(req.backend_hint)) {
// Service is unhealthy, deliver from cache
return (deliver);
} else if (req.url ~ "^/api/ezp/v2" && req.http.referer ~ "/ez$") {
// Request is for Platform UI for REST API, fetch it
return (miss);
}

// By default deliver cache, automatically triggers a background fetch
return (deliver);
}

// fetch & deliver once we get the result
return (miss);
}

// Called when the requested object has been retrieved from the backend
sub vcl_backend_response {

if (bereq.http.accept ~ "application/vnd.fos.user-context-hash"
&& beresp.status >= 500
) {
return (abandon);
}

// Check for ESI acknowledgement and remove Surrogate-Control header
if (beresp.http.Surrogate-Control ~ "ESI/1.0") {
unset beresp.http.Surrogate-Control;
set beresp.do_esi = true;
}

// Make Varnish keep all objects for up to 1 hour beyond their TTL, see vcl_hit for Request logic on this
set beresp.grace = 1h;
}

// Handle purge
// You may add FOSHttpCacheBundle tagging rules
// See http://foshttpcache.readthedocs.org/en/latest/varnish-configuration.html#id4
sub ez_purge {

# Support how purging was done in earlier versions, this is deprecated and here just for BC
if (req.method == "BAN") {
if (!client.ip ~ invalidators) {
return (synth(405, "Method not allowed"));
}

if (req.http.X-Location-Id) {
ban("obj.http.X-Location-Id ~ " + req.http.X-Location-Id);
if (client.ip ~ debuggers) {
set req.http.X-Debug = "Ban done for content connected to LocationId " + req.http.X-Location-Id;
}
return (synth(200, "Banned"));
}
}

if (req.method == "PURGE") {
if (!client.ip ~ invalidators) {
return (synth(405, "Method not allowed"));
}

# If http header "key" is set, we assume purge is on key and you have Varnish xkey installed
if (req.http.key) {
# By default we recommend using soft purge to respect grace time, if you need to hard purge use:
# set req.http.n-gone = xkey.purge(req.http.key);
set req.http.n-gone = xkey.softpurge(req.http.key);

return (synth(200, "Invalidated "+req.http.n-gone+" objects"));
}

# if not, then this is a normal purge by url
return (purge);
}
}

// Sub-routine to get client user context hash, used to for being able to vary page cache on user rights.
sub ez_user_context_hash {

// Prevent tampering attacks on the hash mechanism
if (req.restarts == 0
&& (req.http.accept ~ "application/vnd.fos.user-context-hash"
|| req.http.x-user-hash
)
) {
return (synth(400));
}

if (req.restarts == 0 && (req.method == "GET" || req.method == "HEAD")) {
// Backup accept header, if set
if (req.http.accept) {
set req.http.x-fos-original-accept = req.http.accept;
}
set req.http.accept = "application/vnd.fos.user-context-hash";

// Backup cookie heder if set and only forward session ID to hash lookup, as hash cache will vary on cookie.
if (req.http.cookie) {
set req.http.x-fos-original-cookie = req.http.cookie;
set req.http.cookie = ";" + req.http.cookie;
set req.http.cookie = regsuball(req.http.cookie, "; +", ";");
set req.http.cookie = regsuball(req.http.cookie, ";(eZSESSID[^=]*)=", "; \1=");
set req.http.cookie = regsuball(req.http.cookie, ";[^ ][^;]*", "");
set req.http.cookie = regsuball(req.http.cookie, "^[; ]+|[; ]+$", "");

if (req.http.cookie == "") {
// If there are no more cookies, remove the header to get page cached.
unset req.http.cookie;
}
}

// Backup original URL
set req.http.x-fos-original-url = req.url;
set req.url = "/_fos_user_context_hash";

// Force the lookup, the backend must tell not to cache or vary on all
// headers that are used to build the hash.
return (hash);
}

// Rebuild the original request which now has the hash.
if (req.restarts > 0
&& req.http.accept == "application/vnd.fos.user-context-hash"
) {
set req.url = req.http.x-fos-original-url;
unset req.http.x-fos-original-url;
if (req.http.x-fos-original-accept) {
set req.http.accept = req.http.x-fos-original-accept;
unset req.http.x-fos-original-accept;
} else {
// If accept header was not set in original request, remove the header here.
unset req.http.accept;
}

if (req.http.x-fos-original-cookie) {
set req.http.cookie = req.http.x-fos-original-cookie;
unset req.http.x-fos-original-cookie;
}

// Force the lookup, the backend must tell not to cache or vary on the
// user context hash to properly separate cached data.

return (hash);
}
}

sub vcl_deliver {
// On receiving the hash response, copy the hash header to the original
// request and restart.
if (req.restarts == 0
&& resp.http.content-type ~ "application/vnd.fos.user-context-hash"
) {
set req.http.x-user-hash = resp.http.x-user-hash;

return (restart);
}

// If we get here, this is a real response that gets sent to the client.

// Remove the vary on user context hash, this is nothing public. Keep all
// other vary headers.
set resp.http.Vary = regsub(resp.http.Vary, "(?i),? *X-User-Hash *", "");
set resp.http.Vary = regsub(resp.http.Vary, "^, *", "");
if (resp.http.Vary == "") {
unset resp.http.Vary;
}

// Sanity check to prevent ever exposing the hash to a client.
unset resp.http.x-user-hash;

if (client.ip ~ debuggers) {
if (resp.http.X-Varnish ~ " ") {
set resp.http.X-Cache = "HIT";
} else {
set resp.http.X-Cache = "MISS";
}
} else {
// Remove tag headers when delivering to non debug client
unset resp.http.xkey;
}
}