Manage charms

See also: Juju | Charm

Deploy a charm

The Terraform Provider for Juju does not support deploying a local charm.

To deploy a Charmhub charm, in your Terraform plan add a juju_application resource, specifying the target model and the charm you want to deploy:

resource "juju_application" "this" {
  model = juju_model.development.name

  charm {
    name = "hello-kubecon"
  }
}

You can also specify a charm channel and revision. For example:

resource "juju_application" "this" {
    model = <model>
    charm {
        name     = "<charm-name>"
        channel  = "<channel-name>"
        revision = "<revision-number>"
    }
}

This works as follows:

  • If both channel and revision are specified (recommended for reproducibility), the Terraform provider will deploy the requested revision.

  • If only channel is specified, the provider will deploy the latest revision available in that channel. The charm will not be refreshed on subsequent terraform apply runs.

  • If only revision is specified, the provider will try to deploy that revision from the default channel (as set for the charm on Charmhub); if not available, the result will be an error.

  • If neither field is specified, the provider will deploy the latest revision from the default channel (as set for the charm on Charmhub). The charm will not be refreshed on subsequent terraform apply runs.

If the charm has any resources, and your Terraform plan does not specify them explicitly, resources will come from the tip of the specified or inferred channel.

Update a charm

To update a charm, in the application’s resource definition, in the charm attribute, use a sub-attribute specifying a different revision or channel. For example:

resource "juju_application" "this" {
  model = juju_model.development.name

  charm {
    name = "hello-kubecon"
    revision = 19
  }

}

The Terraform provider does not support refreshing the charm when the revision is not specified. When unset, the revision number is determined during application creation. If you wish to keep the revision unset, you can refresh the application manually using the juju CLI. However, note that setting both channel and revision makes for a more reproducible deployment.

Remove a charm

As a charm is just the means by which (an) application(s) are deployed, there is no way to remove the charm / bundle. What you can do, however, is remove the application / model.