after upgrade to Spring Boot 2, how to expose cache metrics to prometheus?

Question

I recently upgraded a spring boot application from 1.5 to 2.0.1. I also migrated the prometheus integration to the new actuator approach using micrometer. Most things work n

Answer 1

As you've answered my question, I can provide an answer for this.

my caches get created through scheduled tasks later on

Then this section of the doc applies to you:

Only caches that are available on startup are bound to the registry. For caches created on-the-fly or programmatically after the startup phase, an explicit registration is required. A CacheMetricsRegistrar bean is made available to make that process easier.

So you have to register such caches yourself, hopefully it is pretty easy, something like:

public class MyComponent {

    private final CacheMetricsRegistrar cacheMetricsRegistrar;
    private final CacheManager cacheManager

    public MyComponent(CacheMetricsRegistrar cacheMetricsRegistrar,
                CacheManager cacheManager) { ... }

    public void register() {
         // you have just registered cache "xyz"
         Cache xyz = this.cacheManager.getCache("xyz");
         this.cacheMetricsRegistrar.bindCacheToRegistry(xyz);
    }

}

you can include this code in your existing code. If you don't want to do that, then you need something else that runs after your existing code to register those caches to the registry.