Move CTL logging logic over to CTL package

[nsmith5]

Summary

In an attempt to de-cluster the all powerful api.(*api).signingCert method, I've moved to logging logic for the CT log client over into the CT log package. This is achieved by

• Abstracting the CTL client into an interface
• Creating a ctl.WithLogging(inner ctl.Client, logger *Logger) ctl.Client middleware to instrument the client
• Finally removing the logging from the signingCert method

Release Note

NONE

[lukehinds]

I think this is a worthwhile refactor. Main observation so far is only a nit pick. We have the actual CTL POST request under pkg/ctl/logging.go - is logging here meant to mean "logging an entry (to the CTL)" or logging as in a logger?

[nsmith5]

😆 Yeah I was wringing my hands on how to write the commit messages because of that too. The pkg/ctl/logging.go contains a middleware for logging as in a logger. Perhaps we it should be pkg/ctl/logger.go and the middleware should be named WithLogger? I'm definitely open to more clear naming if anyone can thing of something

[bobcallaway]

I just wanted to note that we don't really have test coverage on this change with the KinD tests ☹️ (not your fault @nsmith5):

fulcio/.github/workflows/verify-k8s.yml

Line 198 in 230f809

ct-log-url: ""

[nsmith5]

Ahhh but it is definitely my fault that I got lazy and didn't unit test this. That is easy so I'm going to do that! @lukehinds Did you want to me to change the names around or are you ok with them?

[lukehinds]

Ahhh but it is definitely my fault that I got lazy and didn't unit test this. That is easy so I'm going to do that! @lukehinds Did you want to me to change the names around or are you ok with them?

Maybe CTLloggingClient pkg/ctl/ctl_logging.go etc?

[nsmith5]

Alrighty! Clarified the naming a bit and adding some docs to clarify the that logging means writing helpful stuff to console in this case. Also added some unit testing for the logger!