Configurable metrics

[potkae]

This adds the possibility to rename metrics and the labels.
The solution is extendable for other possible metric specific configuration as well as adding new metrics.

Example usage to rename a default metric

use actix_web_prom::{PrometheusMetricsBuilder, ActixMetricsConfiguration};

PrometheusMetricsBuilder::new("api")
    .endpoint("/metrics")
    .metrics_configuration(
        ActixMetricsConfiguration::default()
        .http_requests_duration_seconds_name("my_http_request_duration"),
    )
    .build()
    .unwrap();

[potkae]

@nlopes What do you think about this?

[vriesk]

@CommanderStorm friendly ping? :)

[CommanderStorm]

@CommanderStorm friendly ping? :)

Ping about what?

[vriesk]

@CommanderStorm friendly ping? :)

Ping about what?

@potkae's question in the comment above.

[CommanderStorm]

I am fine with the rationale.
When I made that comment I was under the impression that adding labels is something uncommon => this is why I made the comments.
Without the builder pattern the second change also makes less sense.

[vriesk]

Okay then - would it be possible to merge the PR now?

[potkae]

Okay then - would it be possible to merge the PR now?

Not sure if anyone except @nlopes has write access to merge? Would need his review.

[nlopes]

Apologies, been away from this for some time. I'm going to try my very best to deal with some of these PRs, including this one. Bear with me.

[nlopes]

If you don't mind rebasing and resolving the conflicts, I can then take a look. Thanks!

[potkae]

@nlopes Sorry for the delay, I was also away for a bit. It's now rebased & ready for review

[nlopes]

Thanks for doing that. Will try to review this week.

[potkae]

@nlopes I'm not entirely sure how I would rebase this now with #74 merged. I think something like configure_labels function - only changing the labels for all default metrics - for ActixMetricsConfiguration struct could do the trick and enable both use cases, but that would be a breaking change compared to current main. Would you mind taking a look at it yourself?
@mstyura would you have an opinion?

[mstyura]

As far as I see the changes I've introduced regarding http version label was not released yet, so it should not be a breaking change to modify implementation to configure http version in a way you are proposing in this PR.

[potkae]

@mstyura @nlopes This is now restructured on top of the latest main. Let me know what you think.

[vriesk]

@nlopes friendly ping :)

[potkae]

@nlopes I noticed some of your test runs were failing. cargo fmt linting fixes are now pushed.

[potkae]

@nlopes rebased this again, ready for review & merging.