Metrics don't show up on the /prometheus endpoint - spring-boot

Question

I have two services, ping and pong where ping sends requests to pong. This metric shows up on the /metrics endpoint for the ping service:
gauge.servo.hystrix.hystrixcommand.http://pong.pongclient#hello().90
but it doesn't appear on the /prometheus endpoint. Other metrics appear on this endpoint, but not the servo metrics with information about Feign/Hystrix http requests.
How do I get those metrics to appear on the /prometheus endpoint?
I have the following dependencies on my build.gradle
compile 'org.springframework.boot:spring-boot-starter-web'
compile 'org.springframework.boot:spring-boot-starter-actuator'
compile 'org.springframework.cloud:spring-cloud-starter-eureka'
compile 'org.springframework.cloud:spring-cloud-starter-hystrix'
compile 'org.springframework.cloud:spring-cloud-starter-feign'
compile 'org.springframework.retry:spring-retry'
compile "io.micrometer:micrometer-core:${micrometerVersion}"
compile "io.micrometer:micrometer-spring-legacy:${micrometerVersion}"
compile "io.micrometer:micrometer-registry-prometheus:${micrometerVersion}"
with the following versions
springCloudVersion = 'Dalston.SR4'
micrometerVersion = '1.0.0-rc.4'
The code can be found here https://github.com/fiunchinho/spring-resiliency

Answer 1

You need to manually add the plugin for Hystrix:
HystrixPlugins.getInstance().registerMetricsPublisher(new MicrometerMetricsPublisher(Metrics.globalRegistry));
You could add it in a #PostConstruct in a configuration.
I've created https://github.com/micrometer-metrics/micrometer/issues/237 to address the shortcoming in the future.

Answer 2

checketts' answer did not work for me and threw a java.lang.IllegalStateException: Another strategy was already registered. on startup, but adding the HystrixMetricsBinder bean, which does more or less the same internally, did the trick.
#Configuration
public class MetricsConfig {
#Bean
HystrixMetricsBinder registerHystrixMetricsBinder() {
return new HystrixMetricsBinder();
}
}
taken from https://stackoverflow.com/a/52740957/60518

Answer 3

You need to instrument and configure the spring boot services to monitor with prometheus as follows:
You need to include a dependency in the gradle.build file
You need to implement Metric endpoint
You need to add the standard exporters from Prometheus JVM
For more implementation details on how to do it see the examples here and also here