CSS-5866 - Add all Juju providers to JIMM's global provider registry

[kian99]

Description

There is currently a bug in JIMM that makes it difficult to add a new cloud to a controller managed by JIMM. If one bootstraps a controller, then adds some clouds to it, you can then add that controller to JIMM and JIMM will retrieve the list of clouds available on that controller without an issue.

But, if you do the above, and then want to add a new cloud to a controller, you are supposed to do that through the jimmctl command add-cloud-to-controller which will add the cloud to the controller and then add it to JIMM's state.

Unfortunately that command fails with the following error (taken from when Field engineering tried this):

jimmctl add-cloud-to-controller main-controller maas-test --cloud=./maas-cloud.yaml
{}
ERROR error reading cloud from file: no registered provider for "maas"

The error "no registered provider" actually comes from Juju here which is called by the jimmctl client here when it validates the cloud config file. It throws the error because there is a concept of registered "providers" in Juju where providers are a computing or storage provider that can back Juju like aws, azure, gce, maas, openstack, etc. The cloud providers are registered against a globalProviders map (contained inside the environs Juju package) via the init() method of each provider. Some examples below:
https://github.com/juju/juju/blob/2.9/provider/ec2/init.go
https://github.com/juju/juju/blob/2.9/provider/azure/init.go
https://github.com/juju/juju/blob/2.9/provider/maas/init.go

In order to ensure that jimmctl also has these providers registered in its instance of the globalProviders map, we can simply import the github.com/juju/juju/provider/all package without using it, but simply for its side effects.

Fixes CSS-5866

Update: Also adds the --force flag to jimmctl add-cloud-to-controller to match juju add-cloud --force

Engineering checklist

Check only items that apply

• Documentation updated
• Covered by unit tests
• Covered by integration tests

Test instructions

Still need to add tests but I added the following lines to func (c *addCloudToControllerCommand) Run(ctxt *cmd.Context) error

		providers := environs.RegisteredProviders()
		fmt.Printf("Providers: %v", providers)

Before the change to import all provider:
Providers: [kubernetes]{}
After:
Providers: [ec2 equinix kubernetes azure maas manual oci openstack vsphere gce lxd]{}

Notes for code reviewers

[alesstimec]

LGTM, but.. could we add a unit test for this? a test that calls readCloudFromFile and see if that goes ok?

[kian99]

@alesstimec Yip, that was on my mind, I'll add that.

[ale8k]

approving, but perhaps explain this in standup again for me about the whole provider concept, I sort of understand but I think in standup can clear it up better

[kian99]

Added a test but this required a lot more changes to ensure we pass along the force flag which wasn't used before. This is pretty important to add for clients. The reasoning:

• Juju does a check here to ensure that the cloud you are adding is compatible with the controller's cloud. This is a matrix mapping known compatible clouds but only includes clouds "kubernetes", "lxd", "maas" and "openstack".
• Clients could have custom cloud names and without the force flag, would never be able to add clouds to their controllers.

[alesstimec]

feels like we could have one table test for these three test cases

[ale8k]

Yeah, think it might make it clearer too

[alesstimec]

same here.. a table test with two test cases..

[kian99]

I don't like this field but the previous tests were checking that the controller has a new cloud, which was always on the 2nd index since each test ran in an clean database. Now that these are in a single table test, they are a lot faster since the whole test suite doesn't need to be start/stopped every time but the database is shared between the tests. Open to suggestions on this.

[kian99]

Will add the comment about why the s.RefreshControllerAddress(c) function is needed separately. Need to follow this up with some extra checks and I don't want to the CI to run again for just 1 additional comment added.