create-storage-pool unnecessarily requires key=value pairs

[Roger Peppe]

The create-storage-pool command implies in its usage information that the key-value attributes are optional:

    Usage: juju create-storage-pool [options] <name> <provider> [<key>=<value> [<key>=<value>...]]

However the command fails if you don't provide at least one key-value pair.
Given that some of the storage providers don't seem to have any keys defined (see for example the "gce" provider in https://jujucharms.com/docs/devel/charms-storage#storage-providers), requiring them seems unnecessary.

The usage information for create-storage-pool should probably also point to somewhere where the available providers and their attributes are defined (ideally in juju help, because the online docs might be for a different juju version than is being run on the command line).

[Anastasia (anastasia-macmood)]

I'll adjust the help text for the command as well the check.

However, we do not have a dedicated 'juju help' that describes providers better than what is on https://jujucharms.com/docs/devel/charms-storage#storage-providers. AFAIK, this is the point of truth in terms of documentation and we do make an effort to keep it current.

[Anastasia (anastasia-macmood)]

Cut-and-paste excitement... Of course, the point of truth is in 'stable' not 'devel' stream - https://jujucharms.com/docs/stable/charms-storage#storage-providers

[Anastasia (anastasia-macmood)]

PR against develop: https://github.com/juju/juju/pull/8648

[Anastasia (anastasia-macmood)]

Backport for 2.3: https://github.com/juju/juju/pull/8652