How-to manage actions¶

Juju users can run actions in charms using the juju run command. Here we cover how you can use goops to handle those actions in your charm.

1. Declare actions¶

Declare the actions in you charm's charmcraft.yaml file. For example:

actions:
  get-password:
    description: Return the password for the specified user.
    params:
      username:
        type: string
        description: >-
            The username for which to return the password.
    required: [username]

Note

For more information on the charmcraft.yaml charm definition, read the official charmcraft documentation.

2. Read the action name¶

You can read the action name in your charm using ReadEnv():

package main

import (
    "os"

    "github.com/gruyaume/goops"
    "github.com/gruyaume/goops/internal/charm"
)

func main() {
    env := goops.ReadEnv()

    if env.ActionName != "" {
        goops.LogInfof("Action name: %s", env.ActionName)

        switch env.ActionName {
        case "get-password":
            err := charm.HandleGetPasswordAction()
            if err != nil {
                goops.LogErrorf("Error handling get-password action: %s", err.Error())
                os.Exit(1)
            }

        default:
            goops.LogErrorf("Action '%s' not recognized, exiting", env.ActionName)
            os.Exit(1)
        }
    }
}

3. Handle the action¶

You can handle the action in your charm. Here the charm reads the username parameter from the action and returns a password based on that username:

package charm

import (
    "fmt"

    "github.com/gruyaume/goops"
)

type GetPasswordActionParams struct {
    Username string `json:"username"`
}

func HandleGetPasswordAction() error {
    params := GetPasswordActionParams{}

    err := goops.GetActionParams(&params)
    if err != nil {
        goops.FailActionf("could not get action parameters")
        return fmt.Errorf("could not get action parameters: %w", err)
    }

    if params.Username == "" {
        goops.FailActionf("Username is not set in action parameters")
        return nil
    }

    password := fmt.Sprintf("%s-12345", params.Username)

    err = goops.SetActionResults(map[string]string{
        "password": password,
    })

    if err != nil {
        return fmt.Errorf("could not set action result: %w", err)
    }

    return nil
}

Warning

All action-related functions (ex. GetActionParams, SetActionResults) will fail if they are not called in the context of an action hook. I.e. env.ActionName must not be empty.

Info

Learn more about action management in charms: