Working with actions
Juju charms can describe actions that users can take on deployed applications.
Actions are scripts that can be triggered on a unit via the command line. Parameters for an action are passed as a map, either defined in a YAML file or given through the UI, and are validated against the schema defined in actions.yaml. See Actions for the charm author for more information.
The following commands are specified for dealing with actions:
juju actions- list actions defined for a service
juju list-actions- alias for
juju run-action- queue an action for execution
juju show-action-output- show output of an action by ID
juju show-action-status- show status of all actions filtered by optional ID
Lists the actions defined for a service.
For example, with the ‘git’ charm deployed, you can see which actions it supports with the following command:
juju actions git
You should see something similar to this:
Action Description add-repo Create a git repository. add-repo-user Give a user permissions to access a repository. add-user Create a new user. get-repo Return the repository's path. list-repo-users List all users who have access to a repository. list-repos List existing git repositories. list-user-repos List all the repositories a user has access to. list-users List all users. remove-repo Remove a git repository. remove-repo-user Revoke a user's permissions to access a repository. remove-user Remove a user.
To show the full schema for all the actions on a service, append the
--schema argument to the
actions command. For example, here’s the beginning of the output from
juju actions git --schema --format yaml:
add-repo: additionalProperties: false description: Create a git repository. properties: repo: description: Name of the git repository. type: string required: - repo title: add-repo type: object ...
The full schema is under the
properties key of the root action. Actions rely on JSON-Schema for validation. The top-level keys shown for the action (
properties) may include future additions to the feature.
Triggers an action.
This command takes a unit (or multiple units) as an argument and returns an ID for the action. The ID can be used with
juju show-action-output <ID> or
juju show-action-status <ID>.
If an action requires parameters, these can be passed directly. For example, we could create a new ‘git’ repository by triggering the ‘add-repo’ action and following this with the name we’d like to give the new repository:
juju run-action git/0 add-repo repo=myproject
This will return the ID for the new action:
Action queued with id: 3a7cc626-4c4c-4f00-820f-f881b79586d10
As mentioned, this command can be applied to more than one unit (of the same application). So if there were two git units you can also do:
juju run-action git/0 git/1 add-repo repo=myproject
To run an action on an application leader append the string “/leader” to the application name, like this:
juju run-action postgresql/leader switchover --string-args master=postgresql/1
When running short-lived actions from the command line, it is more convenient to add the
--wait option to this command. This causes the Juju client to wait for the action to run, and then return the results and other information in YAML format.
For example, running the command:
juju run-action git/0 list-repos --wait
Will return something like:
action-id: 09563275-87bc-4224-81ef-8282ad7e9d63 results: docs1: /var/git/docs1.git myproject: /var/git/myproject.git status: completed timing: completed: 2017-06-18 11:20:10 +0000 UTC enqueued: 2017-06-18 11:20:07 +0000 UTC started: 2017-06-18 11:20:10 +0000 UTC
This avoids having to run a separate command to see the results of the action (although you can still run
show-action-output using the action-id that was returned).
For actions which may take longer to return, it is also possible to specify a ‘timeout’ value, expressed in hours(h), minutes(m), seconds(s), milliseconds(ms) or nanoseconds(ns). In this case, if the action has completed before the specified period is up, it will return the results as before. If the action has not completed, the command will simply return the id and status, enabling the user to continue issuing commands. For instance:
juju run-action git/0 list-repos --wait=10ns
Ten nanoseconds isn’t much time to get anything done, so in this case the output will be similar to:
action-id: 10fb05d9-d220-4a07-825e-a1258b1a868b status: pending timing: enqueued: 2017-06-18 11:27:15 +0000 UTC
You can also set parameters indirectly via a YAML file, although you can override those parameters by providing them directly.
repo: myproject sure: no
With the above example
params.yaml file, we could remove the
myproject git repository with the following command:
juju run-action git/0 remove-repo --wait --params=params.yaml sure=yes
If you have an action that requires multiple lines, use YAML quoting to make sure the whitespace is not collapsed into one line, like in this example where
foo is an action and the parameter
bar is defined in the
actions.yaml file shown just after the example:
juju run-action unit/0 foo bar="'firstline secondline thirdline fourthline'"
YAML quoting uses both single ’ and double " quotes to surround the part that should not be moved to one line.
#!/usr/bin/python3 from subprocess import call import sys with open("/tmp/out", mode='w') as out: call(['action-get','bar'],stdout=out) sys.exit(0)
Shows the results returned from an action with the given ID.
To see the output from the
add-repo action we executed earlier, for example, we’d enter the following:
juju show-action-output 3a7cc626-4c4c-4f00-820f-f881b79586d10
This will return something like the following:
results: dir: /var/git/myproject.git status: completed timing: completed: 2018-06-18 13:46:12 +0000 UTC enqueued: 2018-06-18 13:46:11 +0000 UTC started: 2018-06-18 13:46:11 +0000 UTC
Queries the status of an action.
For example, We could check on the progress of git’s
add-repo action with the following command:
juju show-action-status 3a7cc626-4c4c-4f00-820f-f881b79586d1
This will output the status of the action, shown here as ‘completed’:
actions: - id: 3a7cc626-4c4c-4f00-820f-f881b79586d1 status: completed unit: git/0
There are 5 different values for the status of an action:
- pending - the default status when an action is first queued.
- running - the action is currently running.
- completed - the action ran to completion as intended.
- failed - the action did not complete successfully.
- cancelled - the action was cancelled before being run.
To debug actions, use the
debug-hooks command, like this:
juju debug-hooks <service/unit> [action-name action-name2 ...]
For example, if you want to check the
add-repo action of the
git charm, use:
juju debug-hooks git/0 add-repo
Learn more about debugging charms in Debugging hooks.