Spring Boot 3 does not provide a configuration property for configuring red metrics custom tag keys

[ttddyy]

In WavefrontTracingAutoConfiguration, it defines a WavefrontSpanHandler bean.
This passes an empty collection to the redMetricsCustomTagKeys in the constructor.

spring-boot/spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/tracing/wavefront/WavefrontTracingAutoConfiguration.java

Lines 62 to 69 in 0e67fbc

	@Bean
	@ConditionalOnMissingBean
	@ConditionalOnBean(WavefrontSender.class)
	WavefrontSpanHandler wavefrontSpanHandler(WavefrontProperties properties, WavefrontSender wavefrontSender,
	SpanMetrics spanMetrics, ApplicationTags applicationTags) {
	return new WavefrontSpanHandler(properties.getSender().getMaxQueueSize(), wavefrontSender, spanMetrics,
	properties.getSourceOrDefault(), applicationTags, Collections.emptySet());
	}

Per this documentation in Wavefront, the redMetricsCustomTagKeys should be populated by the wavefront.tracing.red-metrics-custom-tag-keys property.
I believe this bean definition is the corresponding part for the property.

So, what the doc mentioned to work, I think populated values need to be passed to redMetricsCustomTagKeys rather than an empty set.

[wilkinsona]

We can't proceed with this until we've got some input from the Wavefront team.

[oppegard]

We (Wavefront team) recommend a new property be added to WavefrontProperties.java: management.wavefront.trace-derived-custom-tag-keys.

While the above property name is different from the Spring Boot 2 property (wavefront.tracing.red-metrics-custom-tag-keys), it matches the name used in other Wavefront Tracing usages documented at https://docs.wavefront.com/tracing_customize_spans_and_alerts.html.

This would be wired into the WavefrontSpanHandler that @ttddyy linked to.

[wilkinsona]

Thanks, @oppegard.

Given that this was supported with Spring Boot 2 and the separate starter (albeit with a different property name), I think we should consider it to be a bug of omission in Spring Boot 3.0.