CircleCI: Twemproxy, Sentinels and TLS

[jlledom]

I counted up to 34 different scenarios we are going to officially support in the next release. Those are the all the possible combinations of: Twemproxy, ACL, TLS, Client TLS verification, Sentinels, Single Instance, Sync and Async.

For instance, these are some examples of possible scenarios:

• Twemproxy in sync mode
• Sentinels in async mode
• Single instance with TLS but not ACL in async mode.
• Sentinels with TLS and ACL, enforcing client certificate verification, in sync mode
• ... Many more.

I think those can be reduced to 10 critical scenarios:

• Single instance, Sync and Async
• Single with TLS and ACL, Sync and Async
• Sentinels, Sync and Async
• Sentinels with TLS and ACL, Sync and Async
• Twempproxy, Sync and Async

Testing these 10 scenarios doesn't test all possible combinations, but tests all the code (except TLS client verification), I think it should be enough.

Since our tests suite always runs once for Sync and once for Async, what we need is to set up 5 CircleCI workspaces to run our tests on. This PR implements all of them.

Jira Issue

https://issues.redhat.com/browse/THREESCALE-10870

Note for reviewers

For further explanation, please read commits descriptions.

[jlledom]

Ideally we would run the tests in a proper container instead of the host. That can be achieved by attaching a volume to the container.

I tried that, but CircleCI doesn't allow attaching a volume to a container when launching containers from the docker executor.

https://circleci.com/docs/using-docker/#docker-benefits-and-limitations

[akostadinov]

I tried that, but CircleCI doesn't allow attaching a volume to a container when launching containers from the docker executor.

If you can run random commands, it can be achieved like this. But as I said, that can be explored in the future.