varnish-cache-reaper
UNMAINTAINED (2018/06/28): While this tool is stable and has been used in production for 4 years, this is no longer maintained and is superseded by varnish-towncrier.
--
Simple python/twisted HTTP daemon forwarding PURGE and BAN requests to multiple varnish (or other proxy) instances.
The daemon forwards all HTTP PURGE and BAN requests using the original Host-header and URL to all configured endpoints. It also supports surrogate keys (cache tags) using the xkey module, it will forward XKey and XKey-Purge headers if present.
This script is designed to run in a supervised environment like supervisord, daemontools or runit. For runit example code see runit-run and runit-log-run.
Usage
usage: varnish-cache-reaper.py [-h] [-v] [-l IP] [-p PORT]
targets [targets ...]
Varnish cache reaper
positional arguments:
targets Endpoint(s) to send PURGE/BAN requests to
optional arguments:
-h, --help show this help message and exit
-v, --version show program's version number and exit
-l IP, --listen-ip IP
IP to listen on, default *
-p PORT, --listen-port PORT
TCP port to listen on, default 8042
VCL example
Varnish 4.x / 5.x
Varnish documentation on purging and banning in varnish 4, or in varnish 5
[...]
# use xkey module
import xkey;
# purgers acl
# - who is allowed to issue PURGE and BAN requests
#
acl purgers {
"localhost";
}
sub vcl_recv {
[...]
if (req.method == "PURGE") {
if (!client.ip ~ purgers) {
return(synth(405,"Method not allowed"));
}
if(req.http.xkey) {
set req.http.n-gone = xkey.softpurge(req.http.xkey);
return (synth(200, "Got " + req.http.xkey + ", invalidated " + req.http.n-gone + " objects"));
}
return (purge);
}
if (req.method == "BAN" && client.ip ~ purgers ) {
# remove leading / to not confuse regular expression
ban(
"obj.http.x-host == " + req.http.host + " && " +
"obj.http.x-url ~ " + regsub(req.url, "^/", "")
);
return(synth(200, "Banned"));
} else {
return(synth(405,"Method not allowed"));
}
[...]
return(hash);
}
sub vcl_backend_response {
[...]
# be friendly to ban lurker
set beresp.http.x-url = bereq.url;
set beresp.http.x-host = bereq.http.host;
[...]
}
sub vcl_deliver {
[...]
# remove some variables we used before
unset resp.http.x-url;
unset resp.http.x-host;
unset resp.http.xkey;
[...]
}
Varnish 3
Varnish documentation on purging and banning in varnish 3.
# purgers acl
# - who is allowed to issue PURGE and BAN requests
#
acl purgers {
"localhost";
}
sub vcl_recv {
[...]
if (req.request == "PURGE" && !client.ip ~ purgers) {
error 405 "Method not allowed";
}
if (req.request == "BAN") {
if (client.ip ~ purgers) {
# remove leading / to not confuse regular expression
ban(
"obj.http.x-host == " + req.http.host + " && " +
"obj.http.x-url ~ " + regsub(req.url, "^/", "")
);
error 200 "Banned";
} else {
error 405 "Method not allowed";
}
}
[...]
return(lookup);
}
sub vcl_hit {
if (req.request == "PURGE") {
purge;
error 200 "Purged";
}
}
sub vcl_miss {
if (req.request == "PURGE") {
purge;
error 200 "Purged";
}
}
sub vcl_fetch {
# be friendly to ban lurker
set beresp.http.x-url = req.url;
set beresp.http.x-host = req.http.host;
}
Example
The following command line will start a service listening on 127.0.0.1:8042 (default port) and will forward all incoming PURGE or BAN requests to http://127.0.0.1:8080 and http://127.0.0.1:8081.
./varnish-cache-reaper.py -l 127.0.0.1 http://127.0.0.1:8080 http://127.0.0.1:8081
To issue a PURGE request, use
curl -X PURGE -H "Host: vhost.whatever" "http://127.0.0.1:8042/foo/bar" > /dev/null
which will send PURGE requests to all endpoints using vhost.whatever as Host: header and /foo/bar as URL.
To issue a PURGE request using a surrogate key, use
curl -X PURGE -H "Host: vhost.whatever" -H "Xkey: some-cache-tag" "http://127.0.0.1:8042/foo/bar" > /dev/null
Dependencies
- Python 2.7
- Twisted, Debian/Ubuntu Package: python-twisted
License
varnish-cache-reaper is licensed under the MIT License.