A Simple Plugin

This section describes how to write, compile, configure, and run a simple Traffic Server plugin. You’ll follow the steps below:

1. Make sure that your plugin source code contains an TSPluginInit initialization function.
2. Compile your plugin source code, creating a shared library.
3. Add an entry to your plugin’s plugin.config file.
4. Add the path to your plugin shared library into the records.config file.
5. Restart Traffic Server.

Compile Your Plugin

The process for compiling a shared library varies with the platform used, so the Traffic Server API provides the tsxs tool which you can use to create shared libraries on all the supported Traffic Server platforms.

Example

Assuming the sample program is stored in the file hello-world.c, you could use the following commands to build a shared library

tsxs -o hello-world.so -c hello-world.c

tsxs can be found in trafficserver-dev package.

This shared library will be your plugin. In order to install it, run

sudo tsxs -o hello-world.so -i

or the equivalent to sudo on your platform.

Update the plugin.config File

Your next step is to tell Traffic Server about the plugin by adding the following line to the plugin.config file. Since our simple plugin does not require any arguments, the following plugin.config will work:

# a simple plugin.config for hello-world
hello-world.so

Traffic Server can accommodate multiple plugins. If several plugin functions are triggered by the same event, then Traffic Server invokes each plugin’s function in the order each was defined in the plugin.config file.

Specify the Plugin’s Location

All plugins must be located in the directory specified by the configuration variable proxy.config.plugin.plugin_dir, which is located in the records.config file. The directory can be specified as an absolute or relative path.

If a relative path is used, then the starting directory will be the Traffic Server installation directory as specified in /etc/traffic_server. The default value is libexec/trafficserver, but this can vary based on how the software was configured and built. It is common to use the default directory. Be sure to place the shared library hello-world.so inside the directory you’ve configured.

Restart Traffic Server

The last step is to start/restart Traffic Server. Shown below is the output displayed after you’ve created and loaded your hello-world plugin.

# ls libexec/trafficserver
hello-world.so*
# bin/traffic_server
[Mar 27 19:06:31.669] NOTE: updated diags config
[Mar 27 19:06:31.680] NOTE: loading plugin 'libexec/trafficserver/hello-world.so'
hello world
[Mar 27 19:06:32.046] NOTE: cache disabled (initializing)
[Mar 27 19:06:32.053] NOTE: cache enabled
[Mar 27 19:06:32.526] NOTE: Traffic Server running

Note: in the example above, Traffic Server notes are directed to the console by specifying E for proxy.config.diags.output.note in records.config. The second note shows Traffic Server attempting to load the hello-world plugin. The third line of Traffic Server output is from your plugin.