Previously, we managed to get rid of the sample on the left bound
later, so the problem didn't show up in the framework tests. But the
subqueries were still evaluation with the sample on the left bound,
taking space and showing up if returning the subquery result directly
(without further processing through PromQL like in all the framework
tests).

Signed-off-by: beorn7 <beorn@grafana.com>

promql: Fix subqueries to be really left-open

Resolves: #15433

When I converted prometheus to use slog in #14906, I update both the
`QueryLogger` interface, as well as how the log calls to the
`QueryLogger` were built up in `promql.Engine.exec()`. The backing
logger for the `QueryLogger` in the engine is a
`util/logging.JSONFileLogger`, and it's implementation of the `With()`
method updates the logger the logger in place with the new keyvals added
onto the underlying slog.Logger, which means they get inherited onto
everything after. All subsequent calls to `With()`, even in later
queries, would continue to then append on more and more keyvals for the
various params and fields built up in the logger. In turn, this causes
unbounded growth of the logger, leading to increased memory usage, and
in at least one report was the likely cause of an OOM kill. More
information can be found in the issue and the linked slack thread.

This commit does a few things:

- It was referenced in feedback in #14906 that it would've been better
  to not change the `QueryLogger` interface if possible, this PR
proposes changes that bring it closer to alignment with the pre-3.0
`QueryLogger` interface contract
- reverts `promql.Engine.exec()`'s usage of the query logger to the
  pattern of building up an array of args to pass at once to the end log
call. Avoiding the repetitious calls to `.With()` are what resolve the
issue with the logger growth/memory usage.
- updates the scrape failure logger to use the update `QueryLogger`
  methods in the contract.
- updates tests accordingly
- cleans up unused methods

Builds and passes tests successfully. Tested locally and confirmed I
could no longer reproduce the issue/it resolved the issue.

Signed-off-by: TJ Hoplock <t.hoplock@gmail.com>

fix!: stop unbounded memory usage from query log

Previously, the api was evaluating this regex to determine if the label
name was valid or not:

https://github.com/prometheus/common/blob/14bac55a992f7b83ab9d147a041e274606bdb607/model/labels.go#L94

However, I believe that the `IsValid()` function is what ought to be
used in the brave new utf8 era.

**Before**

```
$ curl localhost:9090/api/v1/label/host.name/values
{"status":"error","errorType":"bad_data","error":"invalid label name: \"host.name\""}
```

**After**

```
$ curl localhost:9090/api/v1/label/host.name/values
{"status":"success","data":["localhost"]}
```

It's very likely that I'm missing something here or you were already
planning to do this at some point but I just encountered this issue and
figured I'd give it a go.

Signed-off-by: Owen Williams <owen.williams@grafana.com>

Signed-off-by: Owen Williams <owen.williams@grafana.com>

Add support for utf8 names on /v1/label/:name/values endpoint

Signed-off-by: Jan Fajerski <jfajersk@redhat.com>

prepare release 3.0.1