Matching escaped double quotes

[iobestar]

What did you do?
PromQL: metric_foo_bar{name="\"bar\""}

What did you expect to see?
Data endpoints for metric metric_foo_bar with where label 'name' have value '"bar"'

What did you see instead? Under which circumstances?
No data endpoints.

• Prometheus version:
  prometheus, version 2.0.0-beta.0 (branch: master, revision: 2b5d915)
  build user: root@fc24486243df
  build date: 20170712-12:24:53
  go version: go1.8.3

This query works on Prometheus 1.7.1 but on Prometheus 2.0 I had to replace it with regex matcher:
metric_foo_bar{name=~".+bar.+"}

[gouthamve]

@iobestar Can you try: metric_foo_bar{name="\"bar\""} ?

In any case, @brian-brazil WDYT?

[brian-brazil]

That query does not work on 1.x, it should be escaped as you suggest.

[iobestar]

Correction of my initial post I am using escaped double quotes (escape disappear in presentation):
PromQL: metric_foo_bar{name="\"bar\""}

Escaped double quotes works on Prometheus 1.x but it doesn't work on Prometheus 2.0

[juliusv]

Confirmed, this is a bug in the new text protocol parser, which just extracts slices of the underlying input bytes into label values verbatim, without doing any interpretation of escape sequences \n, \", or \\. So it stores the wrong label value, and then of course it can't be selected.

Problematic place in the code: https://github.com/prometheus/prometheus/blob/dev-2.0/pkg/textparse/parse.go#L108-L132

[gouthamve]

Fixed in #2995

[lock]

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