README.rst

vmod-example

notice

For new developments, we recommend to consider using https://github.com/Dridi/vcdk

SYNOPSIS

import example;

DESCRIPTION

Example Varnish vmod demonstrating how to write an out-of-tree Varnish vmod.

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

Installation will require:

• cmake
• make, ninja or another build system
• clang, gcc or another C compiler

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

Building requires the Varnish header files and uses pkg-config to find the necessary paths.

Usage:

mkdir build
cmake -S . -B build

If you have installed Varnish to a non-standard directory, export PKG_CONFIG_PATH pointing to the appropriate path before calling cmake. For instance, when varnishd configure was called with --prefix=$PREFIX, use

export PKG_CONFIG_PATH=${PREFIX}/lib/pkgconfig

Make targets:

• make -C build - builds the vmod.
• make -C build install - installs your vmod.
• make -C build test - runs the unit tests in tests/*.vtc.

You can install your vmod under a specific prefix by adding DESTDIR to the make command line.

USAGE

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");
}

COMMON PROBLEMS

• configure: error: Need varnish.m4 -- see README.rst

  Check whether PKG_CONFIG_PATH and ACLOCAL_PATH were set correctly before calling autogen.sh and configure

• Incompatibilities with different Varnish Cache versions

  Make sure you build this vmod against its correspondent Varnish Cache version. For instance, to build against Varnish Cache 4.1, this vmod must be built from branch 4.1.

START YOUR OWN VMOD

The basic steps to start a new vmod from this example are:

name=myvmod
git clone libvmod-example libvmod-$name
cd libvmod-$name
./rename-vmod-script $name

and follow the instructions output by rename-vmod-script