The spring-integration actuator endpoint doesn't work when multiple MeterRegistry beans are registered

[trask]

Expected Behavior

The spring-integration actuator endpoint should still work when multiple MeterRegistry beans have been registered (which is a use case that the regular spring metrics actuator endpoint supports).

Current Behavior

The spring-integration actuator endpoint doesn't work when multiple MeterMeterRegistry beans have been regsitered, see

spring-integration/spring-integration-core/src/main/java/org/springframework/integration/graph/MicrometerNodeEnhancer.java

Lines 61 to 67 in cfb6333

	Map<String, MeterRegistry> registries = applicationContext.getBeansOfType(MeterRegistry.class, false, false);
	if (registries.size() == 1) {
	this.registry = registries.values().iterator().next();
	}
	else {
	this.registry = null;
	}

Context

The regular spring metrics actuator endpoint supports multiple MeterRegistry beans, and it would be great if the spring-integration actuator endpoint had similar support, see

• https://github.com/spring-projects/spring-boot/blob/c1fcce4a8d057802aca1bad9faddacd96cdb114f/spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/MetricsEndpointAutoConfiguration.java#L45-L47
• https://github.com/spring-projects/spring-boot/blob/c1fcce4a8d057802aca1bad9faddacd96cdb114f/spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/MetricsEndpoint.java#L67-L69

I have not found any workaround to make the spring-integration actuator endpoint work when multiple MeterRegistry beans have been registered.

[artembilan]

I think we can fix it similar way we do in the MicrometerMetricsCaptor:

this.meterRegistry = this.meterRegistryProvider.getIfUnique();

Which is based on this decision:

	/**
	 * Return an instance (possibly shared or independent) of the object
	 * managed by this factory.
	 * @return an instance of the bean, or {@code null} if not available or
	 * not unique (i.e. multiple candidates found with none marked as primary)
	 * @throws BeansException in case of creation errors
	 * @see #getObject()
	 */
	@Nullable
	default T getIfUnique() throws BeansException {

This way MicrometerNodeEnhancer would rely on the mentioned AutoConfiguredCompositeMeterRegistry which is marked as @Primary.