Add clsuterName to support clusters with non-default names

[xirehat]

By adding clusterName to values, you can install OpenCost in clusters with names other than cluster.local and connect to Prometheus correctly.

This fixes #235

[xirehat]

@mattray @toscott @brito-rafa

[AjayTripathy]

Thanks for this PR @xirehat ... can you share a bit more on how this was tested, and regression tested (ie that it still works for clusters using svc.local)?

[xirehat]

When I run helm template opencost -f values.yaml ./ with empty clusterName: "", output shows me this:

...
          env:
            - name: PROMETHEUS_SERVER_ENDPOINT
              value: "http://prometheus-server.prometheus-system.svc.cluster.local:80"
...

When I run helm template opencost -f values.yaml ./ with clusterName: "example.production", output shows me this:

...
          env:
            - name: PROMETHEUS_SERVER_ENDPOINT
              value: "http://prometheus-server.prometheus-system.svc.example.production:80"
...

It works properly. @AjayTripathy

[github-actions]

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[xirehat]

@mattray @toscott @brito-rafa
Why don't you check this PR? Has this project been abandoned?

[toscott]

Hello @xirehat. This project has not been abandoned, but it has not been a focus area for me personally in quite a while.

For your issue, I believe a non obvious workaround to achieve your goal without helm chart changes would be to set:

opencost:
  prometheus:
    external
      enabled: true 
      url: http://prometheus-server.prometheus-system.svc.example.production:80

If you find that too confusing, I'm ok with supporting a cluster domain name override, but I would like to see the default for the value in the values.yaml file instead of embedded in the _helpers.tpl (makes it a bit easier for people to understand what its for when they can see the value.)

If you do choose to proceed with the change, please rebase your pull request and increment the version. I can put aside some time this weekend to review outstanding prs.

Thanks!

[xirehat]

If you find that too confusing, I'm ok with supporting a cluster domain name override, but I would like to see the default for the value in the values.yaml file instead of embedded in the _helpers.tpl (makes it a bit easier for people to understand what its for when they can see the value.)

@toscott I accept your advice. The changes have been applied.