When deploying a service, the charm you use will often support or even require specific configuration options to be set.
Juju provides tools to help manage these options and respond to changes over the lifetime of the service deployment. These options apply to the entire service, as opposed to only a specific unit or relation. The configuration can modified by an administrator at deployment time or after the services are operational.
Discovering service configuration options
You can discover what configuration options are available for a specific charm in various ways
- By running the
juju get <service>command.
- By viewing the charm in the charm store.
- By examining the config.yaml file in the charm itself.
The configurations setting names and the values they take will obviously vary between charms. The options and possible values are all well documented however, so you should consult one of the above sources to find out particular details.
Configuring a service at deployment
It is possible to set configuration values when deploying a service by providing a yaml-formatted file containing configuration values.
For example, upon investigation we discover that the Mediawiki charm allows us to set values for the name of the wiki and the 'skin' to use. We can put these inside a configuration file.
mediawiki: name: Juju Wiki skin: monobook admins: admin:admin
We can then use this configuration when we deploy the service:
juju deploy --config myconfig.yaml mediawiki
Caution: If the yaml configuration file cannot be read or contains some syntax errors or invalid options, you will receive an error message to this effect. However, the service will still be deployed .
Configuring a service which is already deployed
It is possible to set or change configuration of a service which is already deployed.
Before you set any of these options, you may want to check what current options are already set, using the
juju get <service> command. For example:
juju get mediawiki
Should return something like this:
charm: mediawiki service: mediawiki settings: admins: default: true description: Admin users to create, user:pass type: string value: null debug: default: true description: turn on debugging features of mediawiki type: boolean value: false logo: default: true description: URL to fetch logo from type: string value: null name: default: true description: The name, or Title of the Wiki type: string value: Please set name of wiki skin: default: true description: skin for the Wiki type: string value: vector
You can set the options using the
juju set <service>, specifying multiple key=value pairs if necessary:
juju set mediawiki skin=monoblock name='Juju Wiki'
Setting options back to their default value is done using the
unset command followed
by the service and the respective options:
juju unset mediawiki admins name