Default API host and port to 127.0.0.1:4567

[cwjohnston]

Description

This change defaults the configuration for the API to { "host": "127.0.0.1", "port": 4567 } when neither the SENSU_API_URL environment variable is set nor an api configuration scope is defined in the loaded Sensu settings. Prior to this change, undefined api host and port attributes would raise an exception when a plugin attempts to make requests against the Sensu API.

Motivation and Context

This change is intended as a convenience for users running the API on same compute instance as their Sensu server (as is the behavior under Sensu Enterprise). Closes #95.

How Has This Been Tested?

Manually tested in local environment.

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

  Checklist:

• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have updated the Changelog following the conventions laid out on Keep A Changelog

  Known Caveats

With this change, configurations which previously reported the error "api.json settings not found" will now attempt to connect to the api on 127.0.0.1:4567. If the API is not listening on this ip and port combination, connection errors will bubble up from Net::HTTP instead. This will likely take longer than simply raising an exception.

[cwjohnston]

I believe this may close #90 as well.

[portertech]

Let's clean up api_settings(), perhaps we should do something like https://gist.github.com/portertech/77ecd66f88925d163576c9da593a0013

[cwjohnston]

@portertech I've updated the PR per your suggestion

[cwjohnston]

@portertech ready again

[portertech]