Add response to HttpServerMetricsTagsContributor.Context

[AndreasPetersen]

Description

I want to be able to add tags to the HTTP server metric based on the contents of the response body.

HttpServerMetricsTagsContributor.Context only contains the request, however.

Implementation ideas

I can see that the HttpResponse is already available in

quarkus/extensions/micrometer/runtime/src/main/java/io/quarkus/micrometer/runtime/binder/vertx/VertxHttpServerMetrics.java

Lines 193 to 225 in 47a1a8c

	public void responseEnd(HttpRequestMetric requestMetric, HttpResponse response, long bytesWritten) {
	log.debugf("responseEnd %s, %s", response, requestMetric);
	String path = requestMetric.getNormalizedUriPath(
	config.getServerMatchPatterns(),
	config.getServerIgnorePatterns());
	if (path != null) {
	Timer.Sample sample = requestMetric.getSample();
	Tags allTags = Tags.of(
	VertxMetricsTags.method(requestMetric.request().method()),
	HttpCommonTags.uri(path, requestMetric.initialPath, response.statusCode(),
	config.isServerSuppress4xxErrors()),
	VertxMetricsTags.outcome(response),
	HttpCommonTags.status(response.statusCode()));
	if (!httpServerMetricsTagsContributors.isEmpty()) {
	HttpServerMetricsTagsContributor.Context context = new DefaultContext(requestMetric.request());
	for (int i = 0; i < httpServerMetricsTagsContributors.size(); i++) {
	try {
	Tags additionalTags = httpServerMetricsTagsContributors.get(i).contribute(context);
	allTags = allTags.and(additionalTags);
	} catch (Exception e) {
	log.debug("Unable to obtain additional tags", e);
	}
	}
	}
	openTelemetryContextUnwrapper.executeInContext(
	sample::stop,
	requestsTimer.withTags(allTags),
	requestMetric.request().context());
	}
	requestMetric.requestEnded();
	}

and that some tags are already using the HttpResponse. Would it be possible to add HttpResponse to the HttpServerMetricsTagsContributor.Context? However, it seems that the HttpResponse does not contain the body.

[quarkus-bot]

/cc @ebullient (metrics), @jmartisk (metrics)

[geoand]

Using the contents of the response body can be very tricky. What exactly do you need from the body?

[AndreasPetersen]

Thanks for the quick response!

I want to add a tag based on what caused a 401 response code. We are returning the cause in the response body, but I want to be able to tell the cause in metrics as well.

Alternatively I could use a request scoped bean, set a value on it, and then use that in a MeterFilter, but as mentioned in the Quarkus 3.14 migration guide, that's not going to work.

[geoand]

The way Vert.x operates, that won't really work unfortunately

[AndreasPetersen]

Is there any other way where I can add request specific tags, based on what happens in the request?

[geoand]

Can you give me an example of what you would use that for?

[AndreasPetersen]

I want to be able to tell the cause of a 401 status code, so that I can filter metrics based on the cause. For example:

http_server_requests_count{status="401", cause="myCause"}

[geoand]

We can certainly add HttpResponse to HttpServerMetricsTagsContributor.Context, but as mentioned above that would not give you access to the body.
What you could do with it however is add a custom HTTP response header that you would then read in the contributor.

WDYT?

[AndreasPetersen]

I suppose that could work 👍

[geoand]

#45744 adds that feature

[brunobat]

I want to be able to tell the cause of a 401 status code, so that I can filter metrics based on the cause. For example:

http_server_requests_count{status="401", cause="myCause"}

I would advise against this because it will explode the cardinality of the metric.
This type of data should be retrieved from traces, not the metrics themselves.

[AndreasPetersen]

#45744 adds that feature

Thanks!

[AndreasPetersen]

I would advise against this because it will explode the cardinality of the metric.

We are of course aware of this, and are taking steps to ensure it won't be an issue for us. 🙂

This type of data should be retrieved from traces, not the metrics themselves.

We need the data in our metrics 🙂.