promtool: rule update doesn't preserve escaping as needed

[beorn7]

Bug Report

What did you do?

Converted 1.x rules to 2.x YAML format with promtool update rules.

What did you expect to see?

Working 1.x rules resulting in working 2.x rules.

What did you see instead? Under which circumstances?

A double-backslash in an annotation got reduced to single-backslash, while a double-backslash in an expr field was preserved.

This had the effect that the rule was invalid. The double-backslash in the annotation was from within a regexp in a template expression, which became invalid syntax.

Environment

• System information:

  Linux 4.4.0-138-generic x86_64

• Prometheus version:

  I used promtool 2.5.0, not Prometheus.

I am aware that we want to remove the update command anyway. However, I assume the code path to render rules as YAML is used elsewhere, too, and breaking escaping is problematic then, too.

@grobie That's what I referred to @gouthamve perhaps @grobie mentioned that to you.

[beorn7]

Closing this as the update command is gone, and while trying to verify the same problem with the rendering on the Rules tab in the web UI, I could not reproduce the problem.