go-plugin-example

A quick example project using Hashicorp's go-plugin system.

This project attempts to show how go-plugin can be used to satisfy implementations of plugin code called dynamically from a core Go application.

go-plugin provides a system for plugin code to be written in distince processes (implementing agreed upon interfaces). These processes speak to a core Go application via an RPC mechanism.

Note: quick and dirty example from a few hours trying to understand how go-plugin works and can be used in different design patterns.

Goals

This exmaple project demonstrates a simple architectural pattern with the following goals.

• Go developer wishes to allow a plugin sytem for extensibility
• Go developer wishes to decouple external plugins from main application build
• Plugin developers can write/ship custom proprietary plugins if needed

Example Architecture

This example creates a main application that loads and calls plugins from plugin implmentations that have been compiled into plugin binaries. These plugins implment agreed upon interfaces and ahere to a filename pattern of <type>-<name. For example, the plugin named greeter-foo would represent a plugin of type: greeter and implementation: foo. Here we use the term type for a class of plugins that implmenet a similar interface definition.

This example shows how one could interface with two plugin types, each with different implementations.

• main.go - Example of a core GO application that wishes to interact with plugins.
• ./plugin - Go package wrapping up a Manager for loading plugin binaries from specific directories. It also contains interfaces that need to be
• ./plugin/greeter.go - Interfaces for plugins of type greeter
• ./plugin/clubber.go - Interfaces for plugins of type clubber
• ./plugin/config.go - Common items needed for configuring underlying plugin clients/servers (abstracted by go-plugin)
• ./plugin/manager.go - Convenient package for loading/ using plugins by the main application.
• ./plugins - Individual plugin implementations. In the real world these would probably be seperate Git repos for 3rd party plugins.

Setup

1. Make sure you have Go installed and setup
2. Clone the project
3. Get dependencies bash go get github.com/hashicorp/go-plugin
4. Run make in order to build and place the plugins in the expected location bash make clean && make
5. Run the main program bash go run main.go