- Author
Lasse Karstensen
- Date
2013-11-18
- Version
1.0
- Manual section
3
import policy;
The policy vmod allows request policy handling to be done in a separate process.
The goal of this is to simplify the development of advanced decision policies for Varnish.
A policy daemon will be supplied with:
- Metainfo; client IP/port, URI, etc.
- Request headers
- Request body (in 4.0, empty in 3.0)
Example usage can be:
- Request rate limiting (number, size, etc)
- DNS blacklists for expensive POST requests.
- Client profiling/tracking
See the vpol-protocol.txt for a description of the line protocol between libvmod-policy and the policy daemon.
- Prototype
check(STRING S)- Return value
STRING
- Description
Checks with policy server in S, and returns the string provided by it.
- Example
if (policy.check("127.0.0.1:15696") == 400) { error 403 "Forbidden"; }
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
This document is licensed under the same license as the libvmod-policy project. See LICENSE for details.
- Copyright (c) 2013 Varnish Software