vmod-accept

SYNOPSIS

import accept;

DESCRIPTION

accept allows you to sanitize the Accept* headers (mainly Accept, Accept-Charset and Accept-Encoding) by specify one fallback string, and then adding valid values:

new rule = accept.rule("text/plain");
rule.add("text/html");
rule.add("application/json");

You can then use the rule object to filter the headers. The following line will set the accept header to "text/html" or "application/json" if any of them is found in the original header, and will set it to "text/plain" if neither is found:

set req.http.Accept = rule.filter(req.http.Accept);

accept will ignore any parameter found and will just return the first choice found. More info here: https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html

If the idea of this vmod rings a bell, it's probably because it started as a replacement for @cosimo's `varnish-accept-language VCL module <https://github.com/cosimo/varnish-accept-language`_, before the author noticed `his new version<https://github.com/cosimo/libvmod-i18n>`_. However, vmod-accept tries to be more generic, and should be usable with all accept headers and not just the accept-language ones.

FUNCTIONS

The full API is listed in src/vmod_str.vcc.

INSTALLATION

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.

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

Usage:

./autogen.sh
./configure

If you have installed Varnish to a non-standard directory, call autogen.sh and configure with PKG_CONFIG_PATH pointing to the appropriate path. For instance, when varnishd configure was called with --prefix=$PREFIX, use

export PKG_CONFIG_PATH=${PREFIX}/lib/pkgconfig
export ACLOCAL_PATH=${PREFIX}/share/aclocal

The module will inherit its prefix from Varnish, unless you specify a different --prefix when running the configure script for this module.

Make targets:

• make - builds the vmod.
• make install - installs your vmod.
• make check - runs the unit tests in src/tests/*.vtc.
• make distcheck - run check and prepare a tarball of the vmod.

If you build a dist tarball, you don't need any of the autotools or pkg-config. You can build the module simply by running:

./configure
make

Installation directories

By default, the vmod configure script installs the built vmod in the directory relevant to the prefix. The vmod installation directory can be overridden by passing the vmoddir variable to make install.

USAGE

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

import accept;

sub vcl_init {
        new rule = accept.rule("en");
        rule.add("en");
        rule.add("de");
}

sub vcl_recv {
        # filter the Accept-Language header, returning "en" or "de" if
        # found in the header, and "en" otherwise.
        set req.http.Accept-Language = rule.filter(req.http.Accept-Language);
}

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.