Breaking up the config and pubsub packages by dependency

[jprobinson]

One of the largest of complaints against Gizmo so far has been how the toolkit lumps all dependencies into the config and pubsub packages, often requiring users to vendor or fetch an absurd amount of packages just to work with a simple server.

This PR hopes to fix this problem by breaking out the config and pubsub packages into a set of subpackages, which follows a similar structure to Go Kit and it's implementations. The new package structure:

├── config
│   ├── aws
│   ├── combined
│   ├── cookie
│   ├── gcp
│   ├── metrics
│   ├── mongodb
│   ├── mysql
│   └── oracle
├── pubsub
│   ├── aws
│   ├── gcp
│   ├── kafka
│   └── pubsubtest
├── server
└── web

Notable changes:

• config.Config is now config/combined.Config
• config.Server is now server.Config
• If a "config" type got moved to a package with the same name, it is now likely renamed as Config.
  • example: config.MongoDB moved to config/mongodb.Config

[coveralls]

Coverage decreased (-2.4%) to 42.471% when pulling f8b1879 on config-breakout into 46437ab on master.

[basvanbeek]

just a quick browse. I notice there are now multiple different logging packages found (log, kit/log and Sirupsen/Logrus and sometimes a global var initializing for instance Logrus. (see pubsub.go)

If you need to support these various loggers I would suggest building a logger interface which each package can take as a functional option. This way one can write a wrapper around the various logging packages to implement the interface and give that to the gizmo packages... now everybody can keep on using their preferred logging system.

pssst If you want to move to a single logging package.... Go kit ;)

[jprobinson]

Thanks for looking things over, @basvanbeek!

The plan is move towards the one logger, but I couldn't think of any better, small solution at the time of the metrics PR. In the near future, I'll put together a logging PR that will clean things up a bit.

This log problem you mention was here before this PR, though (it was introduced in #59). Did you have any comments on anything new introduced here? If not, I'm going to merge in the next couple hours.

[basvanbeek]

just a couple of minor items which are more in the realm of opinions :)

I would for instance remove global variables (example RequiredAcks = saram.WaitForAll in pubsub/kafka/kafka.go) and have them become consts holding the default values for these items.

Have explicit rather then implicit changes to behavior by functional options to constructors or explicitely set values from your config objects.

[jprobinson]

I actually like that approach and hope we can fold in some of the changes from your fork once we have this merged into master. PRs welcome :)

[coveralls]

Coverage decreased (-2.7%) to 42.471% when pulling d32a935 on config-breakout into f908f58 on master.

[coveralls]

Coverage decreased (-2.7%) to 42.471% when pulling dec1e76 on config-breakout into f908f58 on master.