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An example vmod for Varnish

branch: 3.0
README.rst

vmod_example

Varnish Example Module

Author: Martin Blix Grydeland
Date: 2011-05-26
Version: 1.0
Manual section: 3

SYNOPSIS

import example;

DESCRIPTION

Example Varnish vmod demonstrating how to write an out-of-tree Varnish vmod for Varnish 3.0 and later.

Implements the traditional Hello World as a vmod.

FUNCTIONS

hello

Prototype
hello(STRING S)
Return value
STRING
Description
Returns "Hello, " prepended to S
Example
set resp.http.hello = example.hello("World");

INSTALLATION

This is an example skeleton for developing out-of-tree Varnish vmods available from the 3.0 release. It implements the "Hello, World!" as a vmod callback. Not particularly useful in good hello world tradition,but demonstrates how to get the glue around a vmod working.

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 example;

sub vcl_deliver {
        # This sets resp.http.hello to "Hello, World"
        set resp.http.hello = example.hello("World");
}

HISTORY

This manual page was released as part of the libvmod-example package, demonstrating how to create an out-of-tree Varnish vmod. For further examples and inspiration check the vmod directory:

System Message: ERROR/3 (<string>, line 91)

Unexpected indentation.
https://www.varnish-cache.org/vmods

COPYRIGHT

This document is licensed under the same license as the libvmod-example project. See LICENSE for details.

  • Copyright (c) 2011 Varnish Software
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