subtle change in regex parsing?

[harmw]

We just upgraded from 0.16 to 0.17 and are observing the following change in behavior.

Our Grafana dashboards are sending queries like this:

service_http_server{job="blaze-gateway",status=~"^2"}

This used to work just fine, but now returns no data.
The same is true for this variation of the same query:

service_http_server{job="blaze-gateway",status=~"^20"}

However, the following all do work and return data points:

service_http_server{job="blaze-gateway",status=~"^2.*"}
service_http_server{job="blaze-gateway",status=~"^2.+"}
service_http_server{job="blaze-gateway",status=~"^200"}

Did something subtle change in this area?

[grobie]

Yes, check Regular expression matchers in PromQL are anchored in the changelog. This behavior changed in 0.17.0.

There used to be an example for that in the changelog: 7a0c0c3

[harmw]

That diff shows exactly what is going on, thanks! Looks like we'll have to change some of our queries 😄
As a sidenote, I don't feel that piece of text is just noise since it's a perfect example of what someone needs to change.

[grobie]

Well, as the author of that "noise" I totally agree. @brian-brazil and @fabxc had different opinions about this. There have been many questions about this regex change already.

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.