Why is Varnish not caching?
- by Justin
I am troubleshooting the setup of Varnish 3.x on my Ubuntu server. I'm running Drupal 7 on two sites set up on the box, via named-based vhosts. Before trying to get Varnish to play nice with Drupal I'm trying to just get Varnish to a PNG from cache.
Here are the headers I get from a curl -I request of the PNG file:
HTTP/1.1 200 OK
Server: Apache/2.2.22 (Ubuntu)
Last-Modified: Sun, 07 Oct 2012 21:18:59 GMT
ETag: "a57c2-3850-4cb7ea73db6c0"
Accept-Ranges: bytes
Content-Length: 14416
Cache-Control: max-age=1209600
Expires: Thu, 25 Oct 2012 22:55:14 GMT
Content-Type: image/png
Accept-Ranges: bytes
Date: Thu, 11 Oct 2012 22:55:14 GMT
X-Varnish: 1766703058
Age: 0
Via: 1.1 varnish
Connection: keep-alive
X-Varnish-Cache: MISS
Here is the Varnish VCL file I'm using (It's a default VCL configuration designed for Drupal):
# Default backend definition. Set this to point to your content
# server.
#
backend default {
.host = "127.0.0.1";
.port = "8080";
}
# Respond to incoming requests.
sub vcl_recv {
# Use anonymous, cached pages if all backends are down.
if (!req.backend.healthy) {
unset req.http.Cookie;
}
# Allow the backend to serve up stale content if it is responding slowly.
set req.grace = 6h;
# Pipe these paths directly to Apache for streaming.
#if (req.url ~ "^/admin/content/backup_migrate/export") {
# return (pipe);
#}
# Do not cache these paths.
if (req.url ~ "^/status\.php$" ||
req.url ~ "^/update\.php$" ||
req.url ~ "^/admin$" ||
req.url ~ "^/admin/.*$" ||
req.url ~ "^/flag/.*$" ||
req.url ~ "^.*/ajax/.*$" ||
req.url ~ "^.*/ahah/.*$") {
return (pass);
}
# Do not allow outside access to cron.php or install.php.
#if (req.url ~ "^/(cron|install)\.php$" && !client.ip ~ internal) {
# Have Varnish throw the error directly.
# error 404 "Page not found.";
# Use a custom error page that you've defined in Drupal at the path "404".
# set req.url = "/404";
#}
# Always cache the following file types for all users. This list of extensions
# appears twice, once here and again in vcl_fetch so make sure you edit both
# and keep them equal.
if (req.url ~ "(?i)\.(pdf|asc|dat|txt|doc|xls|ppt|tgz|csv|png|gif|jpeg|jpg|ico|swf|css|js)(\?.*)?$") {
unset req.http.Cookie;
}
# Remove all cookies that Drupal doesn't need to know about. We explicitly
# list the ones that Drupal does need, the SESS and NO_CACHE. If, after
# running this code we find that either of these two cookies remains, we
# will pass as the page cannot be cached.
if (req.http.Cookie) {
# 1. Append a semi-colon to the front of the cookie string.
# 2. Remove all spaces that appear after semi-colons.
# 3. Match the cookies we want to keep, adding the space we removed
# previously back. (\1) is first matching group in the regsuball.
# 4. Remove all other cookies, identifying them by the fact that they have
# no space after the preceding semi-colon.
# 5. Remove all spaces and semi-colons from the beginning and end of the
# cookie string.
set req.http.Cookie = ";" + req.http.Cookie;
set req.http.Cookie = regsuball(req.http.Cookie, "; +", ";");
set req.http.Cookie = regsuball(req.http.Cookie, ";(SESS[a-z0-9]+|SSESS[a-z0-9]+|NO_CACHE)=", "; \1=");
set req.http.Cookie = regsuball(req.http.Cookie, ";[^ ][^;]*", "");
set req.http.Cookie = regsuball(req.http.Cookie, "^[; ]+|[; ]+$", "");
if (req.http.Cookie == "") {
# If there are no remaining cookies, remove the cookie header. If there
# aren't any cookie headers, Varnish's default behavior will be to cache
# the page.
unset req.http.Cookie;
}
else {
# If there is any cookies left (a session or NO_CACHE cookie), do not
# cache the page. Pass it on to Apache directly.
return (pass);
}
}
}
# Set a header to track a cache HIT/MISS.
sub vcl_deliver {
if (obj.hits > 0) {
set resp.http.X-Varnish-Cache = "HIT";
}
else {
set resp.http.X-Varnish-Cache = "MISS";
}
}
# Code determining what to do when serving items from the Apache servers.
# beresp == Back-end response from the web server.
sub vcl_fetch {
# We need this to cache 404s, 301s, 500s. Otherwise, depending on backend but
# definitely in Drupal's case these responses are not cacheable by default.
if (beresp.status == 404 || beresp.status == 301 || beresp.status == 500) {
set beresp.ttl = 10m;
}
# Don't allow static files to set cookies.
# (?i) denotes case insensitive in PCRE (perl compatible regular expressions).
# This list of extensions appears twice, once here and again in vcl_recv so
# make sure you edit both and keep them equal.
if (req.url ~ "(?i)\.(pdf|asc|dat|txt|doc|xls|ppt|tgz|csv|png|gif|jpeg|jpg|ico|swf|css|js)(\?.*)?$") {
unset beresp.http.set-cookie;
}
# Allow items to be stale if needed.
set beresp.grace = 6h;
}
# In the event of an error, show friendlier messages.
sub vcl_error {
# Redirect to some other URL in the case of a homepage failure.
#if (req.url ~ "^/?$") {
# set obj.status = 302;
# set obj.http.Location = "http://backup.example.com/";
#}
# Otherwise redirect to the homepage, which will likely be in the cache.
set obj.http.Content-Type = "text/html; charset=utf-8";
synthetic {"
<html>
<head>
<title>Page Unavailable</title>
<style>
body { background: #303030; text-align: center; color: white; }
#page { border: 1px solid #CCC; width: 500px; margin: 100px auto 0; padding: 30px; background: #323232; }
a, a:link, a:visited { color: #CCC; }
.error { color: #222; }
</style>
</head>
<body onload="setTimeout(function() { window.location = '/' }, 5000)">
<div id="page">
<h1 class="title">Page Unavailable</h1>
<p>The page you requested is temporarily unavailable.</p>
<p>We're redirecting you to the <a href="/">homepage</a> in 5 seconds.</p>
<div class="error">(Error "} + obj.status + " " + obj.response + {")</div>
</div>
</body>
</html>
"};
return (deliver);
}
I'm getting a MISS and age 0 every time. If I'm understanding correctly, this means the file isn't being returned from Varnish's cache. Is there a problem with my Varnish config?
