goops

Develop Reliable, Portable, and Fast Juju Charms in Go

goops is a Go library for developing robust Juju charms. While charm developers traditionally use the ops Python framework, Python's dynamic typing and interpreter-based execution often lead to runtime errors and portability issues across different bases. In contrast, Go compiles to a single, self-contained binary, ensuring greater reliability and consistent behavior in any environment.

Building a charm with goops is 2-3 times faster.

Running charmcraft pack for an X.509 certificates provider charm from a clean cache.

Getting Started

1. Use the Charmcraft go plugin

Use the go plugin to build your charm in charmcraft.yaml:

parts:
  charm:
    source: .
    plugin: go
    build-snaps:
      - go
    organize:
      bin/<your-charm-name>: dispatch

2. Write your charm

Create a main.go file under the cmd/<your-charm-name>/ directory in your charm's root directory. This file will contain the main logic of your charm. Import the goops library and use its functions to interact with Juju. For example:

package main

import (
	"os"

	"github.com/gruyaume/goops"
	"github.com/gruyaume/goops/commands"
)

func main() {
	hookContext := goops.NewHookContext()
	hookName := hookContext.Environment.JujuHookName()
	hookContext.Commands.JujuLog(commands.Info, "Hook name:", hookName)

	statusOpts := &commands.StatusOptions{
		Name:    commands.StatusActive,
		Message: "A happy charm",
	}

	err := hookContext.Commands.StatusSet(statusOpts)
	if err != nil {
		hookContext.Commands.JujuLog(commands.Error, "Could not set status:", err.Error())
		os.Exit(0)
	}

	hookContext.Commands.JujuLog(commands.Info, "Status set to active")
	os.Exit(0)
}

The certificates charm repository provides an example of the library's use.

Reference

Design principles

• Reliability: Our top priority is building predictable and robust charms.
• Simplicity: goops serves as a minimal, one-to-one mapping between Juju concepts and Go constructs. It is not a framework; it does not impose charm design patterns. The library has no dependencies.

Juju compatibility

goops is compatible with Juju 3.6 and later.