Auto-configure observability features introduced in Apache HttpComponents 5.6

[dalbani]

From https://hc.apache.org/httpcomponents-client-5.6.x/observation.html:

Since 5.6, HttpClient ships an optional module, httpclient5-observation, that plugs straight into Micrometer (metrics + observations) and can bridge to OpenTelemetry (traces). The goal is simple: give you drop-in visibility of latency, throughput, I/O, connection-pool health, DNS, and TLS—without rewriting application code or coupling the core client to any monitoring stack.

https://github.com/apache/httpcomponents-client/tree/master/httpclient5-observation/src/test/java/org/apache/hc/client5/http/observation/example contains a couple of examples on how to use this feature.

This would be great if Spring Boot could somehow offer the ability to (easily) activate this functionality.
Preferably via a configuration property. Or at least document how to turn it on in a Spring Boot application.

[snicoll]

Thanks for reporting this @dalbani. I've seen this while working on a problem related to Apache Commons 5.6.

We will have to make sure that Spring Framework works with that version, and it might be problematic considering what we discussed in https://issues.apache.org/jira/browse/HTTPCLIENT-2409.

[bclozel]

See spring-projects/spring-framework#36100

[dalbani]

Very nice to see that HttpComponents has been updated to 5.6 🙏

[snicoll]

This would be great if Spring Boot could somehow offer the ability to (easily) activate this functionality.
Preferably via a configuration property.

There are way too many options to consider a single property. And given the current API, you cannot neither enable/disable support nor know easily if it has been enabled. Adding observations with Spring Boot would lead to duplicate traces as our HTTP clients already do that. Remain the metrics and I am not sure how useful that would be to justify providing auto-configuration for it.

I've added the missing dependency management for httpclient5-observation in the latest snapshot. We've already upgraded so you could give that a try by adding httpclient5-observation to your app and customizing the builder as follows:

@Configuration(proxyBeanMethods = false)
static class TestConfig {

	@Bean
	HttpComponentsClientHttpRequestFactoryBuilder clientHttpRequestFactoryBuilder(MeterRegistry meterRegistry) {
		return ClientHttpRequestFactoryBuilder.httpComponents().withHttpClientCustomizer((builder) -> {
			HttpClientObservationSupport.enable(builder, null, meterRegistry, null, MetricConfig.DEFAULT);
		});
	}

}

Please give it a try and let us know how it goes.

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