Comment 1 for bug 1603640

We want to keep "juju controllers" as a command that always succeeds, and returns instantly. It does this by *only* parsing and printing just the local controllers.yaml file and not making any API calls. This is to avoid the situation where a bad or stuck controller can prevent the user from seeing what controllers they have.

A tabular output option was added to juju show-controller. API calls are made to display the level of access the current user has to that controller, as well as the agent version.

$ juju show-controller --format tabular
CONTROLLER MODEL USER ACCESS CLOUD/REGION VERSION
prod admin@local/controller admin@local superuser lxd/localhost 2.0-beta17.1

show-controller also allows multiple controllers to be specified:

$ juju show-controller --format tabular prod test

We can discuss and tweak the decisions made, and the reasoning for them, if the approach taken is not desirable.