log.SetFlags(0) doesn't remove timestamp from log lines, preventing InferLevels to work properly

[lgfa29]

While working on hashicorp/nomad#11291 I wasn't able to get InferLevels to work properly because the log lines generated by external dependencies still had the timestamp.

Maybe we can extend the search scope from HasPrefix to Contains?

[evanphx]

I don't really want to expand the scope to Contains because it's too easy to get a false positive. Can nomad turn timestamps off on it's logger instead?

[lgfa29]

Yeah, makes sense. I tried to disable the timestamps from Nomad here, but these log lines are coming from external dependencies (like mdns for example). Even calling log.SetFlags in an init function in the main package didn't help.

What do you think about making the search scope configurable? So callers would be able to do something like:

&hclog.StandardLoggerOptions{
    InferLevels: true,
    InferLevelFullLine: true,
})

But with a better name 😅

[evanphx]

Sure, we could introduce additional options. Either TryReallyHardToInfer to use Contains or maybe InferAroundTimestamps that could detect and skip the timestamp?

[lgfa29]

Nice, trying to detect the timestamp seems like a good approach. I will raise a PR soon. Thanks!