javaprometheusspring-boot-actuatoropencensus

Where is the Spring Actuator Controller endpoint and can I call it programmatically with jvm call?

I want to find the actual java class that serves the Spring Actuator endpoint (/actuator).

It's similar to this question in a way, but that person wanted to call it via a network HTTP call. Ideally, I can call it within the JVM to save on the cost of setting up an HTTP connection.

The reason for this is because we have 2 metrics frameworks in our system. We have a legacy metrics framework built on OpenCensus and we migrated to Spring Actuator (Prometheus metrics based on Micrometer). I think the Spring one is better but I didn't realize how much my company built infrastructure around the old one. For example, we leverage internal libraries that use OpenCensus. Infra team is depending on Opencensus-based metrics from our app. So the idea is to try to merge and report both sets of metrics.

I want to create my own metrics endpoint that pulls in data from Opencensus's endpoint and Actuator's endpoint. I could make an HTTP call to each, but I'd rather call them within the JVM to save on resources and reduce latency.

Or perhaps I'm thinking about it wrong. Should I simply be using MeterRegistry.forEachMeter() in my endpoint? In any case, I thought if I found the Spring Actuator endpoint, I can see an example of how they're doing it and mimic the implementation even if I don't call it directly.

Bonus: I'll need to track down the Opencensus handler that serves its endpoint too and will probably make another post for that, but if you know the answer to that as well, please share!

Solution

  • I found out another interesting way of doing this.

    The other answer I gave but it has one issue. It contains duplicate results. When I looked into it, I realized that both OpenCensus and Micrometer were reporting the same result.

    Turns out that the PrometheusScrapeEndpoint implementation uses the same CollectorRegistry that OpenCensus does so the both sets of metrics were being added to the same registry.

    You just need to make sure to provide these beans

    @PostConstruct
public void openCensusStats() {
    PrometheusStatsCollector.createAndRegister();
}

@Bean
public CollectorRegistry collectorRegistry() {
  return CollectorRegistry.defaultRegistry;
}