template: Add reReplaceAll function

[jamesog]

This allows for using string replace inside templates.

e.g.:

{{ replace .GroupLabels.alertname "_" " " -1 }}

[jamesog]

I made this change from the v0.4.2 tag so submitted the PR against the release-0.4 branch, but not sure if this would be wanted against another (newer) branch.

[brian-brazil]

This should go against master.

This should follow the naming and semantics of Prometheus templates: https://prometheus.io/docs/visualization/template_reference/#strings

[stuartnelson3]

@jamesog can you branch from master and add this change? v0.4.x isn't being supported.

[jamesog]

Yep, will do. I've been sick the last couple of days but I'll get to it ASAP.

Can you clarify what you mean about the naming? I was following the example of the join function.

[brian-brazil]

reReplaceAll is the function name in Prometheus.

[jamesog]

Would stringReplace be acceptable?

[brian-brazil]

The naming should be consistent across both.

[jamesog]

Right, but I assume the re in reReplaceAll refers to the fact that it's using regexp.ReplaceAll. In this case I'm using strings.Replace, so I'm just trying to clarify how you would want to name it in this case, or whether you'd prefer it to use regexp instead of strings.

[brian-brazil]

Stick with the regex, if someone has a use case not covered by that we can consider it then.

[jamesog]

Thanks very much, appreciate the clarification. I've made the change to use reReplaceAll as in Prometheus. I haven't been able to test this yet as we're still using 0.4.2 in production, but I'll see if I can do that now.

[jamesog]

That's tested now and working as expected.

[brian-brazil]

Thanks!

[gaelreyrol]

This feature is not included in the latest available release which is obvious but kind of confusing for newbies like me !