Redis TLS for coordination in Gnocchi

[MatusJenca2]

As an operator, I want be able to use TLS with Gnocchi so that i can use Redis with TLS in my cloud.

Currently, there's an upstream PR covering Redis TLS connectivity. This PR covers TLS all the services osing Tooz - see #562. However Gnocchi does not use Tooz to communicate with Redis, instead it uses a custom solution. This code does not parse certificates from URL.

This requires an upstream change in Gnocchi repo.

Acceptance criteria:

• [x] Gnocchi is able to use Redis with TLS on.
• [ ] Kolla Ansible is able to use Gnocchi with Redis and TLS

Definition of Ready:

• [x] User Story is small enough to be finished within one sprint
• [x] User Story is clear and understood by the whole team
• [x] Acceptance criteria are defined
• [x] Acceptance criteria are clear and understood by the whole team

Definition of Done:

• [ ] All acceptance criteria are met
• [ ] Changes have been reviewed
• [ ] CI tests have run successfully
• [ ] Documentation has been updated
• [ ] Release Notes have been updated

[MatusJenca2]

I just found out that it's already there, but it's in a different fromat from what Tooz uses. We may close this issue perhaps

[MatusJenca2]

Update: The change is on master only, not latest release tag.

So we have to wait for the next release of Gnocchi.