Nomad plugin authoring guide

Nomad implements a plugin framework that lets you extend the functionality of some components within Nomad. The design of the plugin system is inspired by the lessons learned from plugin systems implemented in other HashiCorp products such as Terraform and Vault.

The following components are currently pluggable within Nomad:

• Device: Extend workload functionality with a custom hardware device.
• Host volume: Extend workload storage functionality with a plugin specific to your local storage environment.
• Task driver: Extend task execution functionality with a custom task driver.

Architecture

The Nomad task driver and device plugin framework uses the go-plugin project to expose a language-independent plugin interface. Plugins implement a set of gRPC services and methods that Nomad manages by running the plugin and calling the implemented RPCs. As a result, plugins are free to be implemented in the author's language of choice. To facilitate plugin development, a set of Go interfaces and structs exist for each plugin type that abstracts away go-plugin and the gRPC interface. The guides in this documentation reference these abstractions for ease of use.