Juju 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 servicejuju list-actions
- alias foractions
juju run-action
- queue an action for executionjuju show-action-output
- show output of an action by IDjuju show-action-status
- show status of all actions filtered by optional ID
Action commands
juju actions
List 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
...
Note:
the full schema is under the properties
key of the root Action. Juju
Actions rely on JSON-Schema for validation. The
top-level keys shown for the Action (description
and properties
) may
include future additions to the feature.
juju run-action
Trigger 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
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. E.g.:
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 the parameters within the file by providing them directly.
Example params.yaml:
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.
Example actions.yaml:
#!/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)
juju show-action-output
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
juju show-action-status
Query 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.
Debugging actions
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 Juju charms in Debugging hooks.