External Plugins

External plugins are external programs that are built outside of Telegraf that can run through an execd plugin. These external plugins allow for more flexibility compared to internal Telegraf plugins.

• External plugins can be written in any language (internal Telegraf plugins can only be written in Go)
• External plugins can access to libraries not written in Go
• Utilize licensed software that is not available to the open source community
• Can include large dependencies that would otherwise bloat Telegraf
• You do not need to wait on the Telegraf team to publish the plugin and start working with it.
• Using the shim you can easily convert plugins between internal and external use
• Using 3rd-party libraries requiring CGO support

External Plugin Guidelines

The guidelines of writing external plugins would follow those for our general input, output, processor, and aggregator plugins. Please reference the documentation on how to create these plugins written in Go.

For listed external plugins, the author of the external plugin is also responsible for the maintenance and feature development of external plugins. Expect to have users open plugin issues on its respective GitHub repository.

Execd Go Shim

For Go plugins, there is a Execd Go Shim that will make it trivial to extract an internal input, processor, or output plugin from the main Telegraf repo out to a stand-alone repo. This shim allows anyone to build and run it as a separate app using one of the execd plugins:

• inputs.execd
• processors.execd
• outputs.execd

Follow the Steps to externalize a plugin and Steps to build and run your plugin to properly with the Execd Go Shim.

Step-by-Step guidelines

This is a guide to help you set up a plugin to use it with execd:

1. Write a Telegraf plugin. Depending on the plugin, follow the guidelines on how to create the plugin itself using InfluxData's best practices:
   • Input Plugins
   • Processor Plugins
   • Aggregator Plugins
   • Output Plugins
2. Move the project to an external repo, it is recommended to preserve the path structure, but not strictly necessary. For example, if the plugin was at plugins/inputs/cpu, it is recommended that it also be under plugins/inputs/cpu in the new repo. For a further example of what this might look like, take a look at ssoroka/rand or danielnelson/telegraf-execd-openvpn.
3. Copy main.go into the project under the cmd folder. This will be the entrypoint to the plugin when run as a stand-alone program and it will call the shim code for you to make that happen. It is recommended to have only one plugin per repo, as the shim is not designed to run multiple plugins at the same time.
4. Edit the main.go file to import the plugin. Within Telegraf this would have been done in an all.go file, but here we do not split the two apart, and the change just goes in the top of main.go. If you skip this step, the plugin will do nothing.

   _ "github.com/me/my-plugin-telegraf/plugins/inputs/cpu"

5. Optionally add a plugin.conf for configuration specific to the plugin. Note that this config file must be separate from the rest of the config for Telegraf, and must not be in a shared directory where Telegraf is expecting to load all configs. If Telegraf reads this config file it will not know which plugin it relates to. Telegraf instead uses an execd config block to look for this plugin.
6. Add usage and development instructions in the homepage of the repository for running the plugin with its respective execd plugin. Please refer to openvpn install and awsalarms install for examples. Include the following steps:
   1. How to download the release package for the platform or how to clone the binary for the external plugin
   2. The commands to build the binary
   3. Location to edit the telegraf.conf
   4. Configuration to run the external plugin with inputs.execd, processors.execd, or outputs.execd
7. Submit the plugin by opening a PR to add the external plugin to the /EXTERNAL_PLUGINS.md list. Please include the plugin name, link to the plugin repository and a short description of the plugin.