Override and pass in additional grafana agent config keys

[patmaddox]

#159 was missing a commit that we had on a different branch when testing. Sorry for not being more careful there.

This permits template_file to be overridden, and for additional variables to be passed through to the template file.

Change description

The config currently passes an explicit list of keys to grafana agent config. Any keys not in that list will not get sent.

This change allows us to send additional grafana agent config keys that will be passed through to the template file.

It's necessary to enable the functionality of #159 - without it, a template_file config won't get passed to the grafana agent config.

Checklist

We have deployed this branch to production and confirmed that it fixes the problem described above.

• I have added unit tests to cover my changes.
• I have added documentation to cover my changes.
• My changes have passed unit tests and have been tested E2E in an example project.

[patmaddox]

@akoutmos what can I do to help get this merged?

[akoutmos]

Sorry about that @patmaddox. Totally forgot about this one! Looks good to me. Will merge once CI passes!

[coveralls]

Coverage remained the same at 79.297% when pulling d9fb823 on patmaddox:override-and-add-agent-config into 859cecd on akoutmos:master.