import softpurge;

Softpurge is cache invalidation in Varnish that reduces TTL but keeps the grace value of a resource.

This makes it possible to serve purged content to users if a backend is unavailable and fresh content can not be fetched.

Prototype

softpurge()

Return value

NULL

Description

Performs a soft purge. Valid in vcl_hit and vcl_miss.

Example

sub vcl_hit {
        if (req.method == "PURGE") {
                softpurge.softpurge();
        }
}

The source tree is based on autotools to configure the building, and does also have the necessary bits in place to do functional unit tests using the varnishtest tool.

Usage:

./configure VARNISHSRC=DIR [VMODDIR=DIR]

VARNISHSRC is the directory of the Varnish source tree for which to compile your vmod. Both the VARNISHSRC and VARNISHSRC/include will be added to the include search paths for your module.

Optionally you can also set the vmod install directory by adding VMODDIR=DIR (defaults to the pkg-config discovered directory from your Varnish installation).

Make targets:

• make - builds the vmod
• make install - installs your vmod in VMODDIR
• make check - runs the unit tests in src/tests/*.vtc

In your VCL you could then use this vmod along the following lines:

import softpurge;

sub vcl_recv {
        if (req.method == "PURGE") { return(hash); }
}
sub vcl_fetch { set beresp.grace = 10m; }

sub vcl_hit {
        if (req.method == "PURGE) {
                softpurge.softpurge();
                return (synth(200, "Successful softpurge"));
        }
}
sub vcl_miss {
        if (req.method == "PURGE) {
                softpurge.softpurge();
                return (synth(200, "Successful softpurge"));
        }
}

• Copyright (c) 2014 Varnish Software