io.micrometer contains disk space metrics (io.micrometer.core.instrument.binder.jvm.DiskSpaceMetrics) but it doesn't seems to be enabled by default. There are no metric data. How do i enable this metric that it can be used by prometheus?
Metrics about disk space are exposed as part of the health endpoint, which is provided by Spring Boot Actuator (dependency: org.springframework.boot:spring-boot-starter-actuator).
The health endpoint can be enabled as follows in the application.properties file (by default, it should be enabled):
management.endpoints.web.exposure.include=health
Then, you can enable detailed disk space information as follows:
management.endpoint.health.show-components=always
management.endpoint.health.show-details=always
management.health.diskspace.enabled=true
In production, you might want to use when_authorized instead of always, so that the information is not publicly available.
Finally, you can see the disk info through the HTTP endpoint /actuator/health.
More info in the official docs.
The same metrics for Prometheus will be added in a future Spring Boot version. There's an open PR to add auto configuration for that. In the meantime, you can configure a bean yourself taking inspiration from the PR.
@Bean
public DiskSpaceMetrics diskSpaceMetrics() {
return new DiskSpaceMetrics(new File("."));
}