Make dashboard portable

[deajan]

What is the purpose of this change? What does it change?

Allows to select datasource when first importing into grafana, thus making the dashboard portable.

Was the change discussed in an issue or in the forum before?

Don't think this was discussed anywhere

Checklist

• [X] I have enabled maintainer edits for this PR
• [N/A] I have added tests for all changes in this PR
• [N/A] I have added documentation for the changes (in the manual)
• [N/A] There's a new file in changelog/unreleased/ that describes the changes for our users (template here)
• [N/A] I have run gofmt on the code in all commits
• [N/A] All commit messages are formatted in the same style as the other commits in the repo
• [X] I'm done, this Pull Request is ready for review

[wojas]

Thanks! Do you have a link that documents this?

I find the ${DS_PROMETHEUS-INFRA} with - a bit weird and I cannot find this exact name anywhere. I can find mentions of DS_PROMETHEUS, but mostly from people that have issues with it and had to replace it manually with the actual name. Is there a minimum Grafana version for this?

Does https://github.com/restic/rest-server/tree/master/examples/compose-with-grafana still work with this?

[deajan]

I actually could have chosen any variable name as long as I specify it in "__inputs" part of the json file. DS_PROMETHEUS must be included in the JSON file, which I did.

To be honest, I don't know what minimum version of grafana is required for this to work (I use 9.x).

I cannot guarantee this will work with your current composer setup, but should work since you ask to define a datasource named prometheus, which is the default I setup the DS_PROMETHEUS variable with.

[deajan]

You could actually make the dashboard portable itself by exporting it's JSON, see https://stackoverflow.com/questions/54776604/how-can-i-change-the-datasource-for-a-grafana-dashboard