Demo of Actuator, Micrometer for metrics

General Areas

1. Created a HelloWorld 'page' available at http://localhost:8080/test/

Actuator Areas

1. Generated project using https://start.spring.io/

2. Expose all endpoints

     endpoints:
       web:
         exposure:
           include: "*"

3. For fun, changed base path to 'anything'

   management:
    endpoints:
       web:
         base-path: /anything
   

4. Add info area to application.yml

   info:
     app:
       version: 0.0.1
       name: just anything we wish
       extra: this too
       java:
         version: ${java.version}
     author:
       name: abc

5. Add Extender for information (which would allow us to note other information desired at runtime)

   Class ExtendedInfo does this by retrieving he existing info map and adding to it as well as using example of noting a status if desired

6. Allow shutdown to test this

   management:
     endpoint:
       shutdown:
         enabled: true

   By posting to shutdown endpoint, can shut down

   curl -X POST http://localhost/anything/shutdown
   

7. Show all health

   management:
     endpoint:
       health:
         show-details: always
   

8. Add CustomHealthIndicator

   Shows just how simple the work here is

9. Adding a failure health through CustomFailingHealthIndicator just to show it

Micrometer Areas

Micrometer is provided through Spring Boot as well, out of the box.

1. Created a MetricsConfig class

   This configuration allows us to specify any number of tags that we wish. This particular example provides tags from application settings as well as fixed values.

2. Created custom metric through HelloService

   By creating a custom Bean and then injecting the metrics registry, we can add any values we wish

   We can also see the values at http://localhost:8080/anything/metrics/received.messages

   I also used the @Slf4j annotation within the service simply to show how easy it is to log

3. Created a HealthMetrics metric

   Based on https://micrometer.io/docs/guide/healthAsGauge

4. Created custom LogMeterRegistry that logs metrics from Micrometer into the spring log

   By adding a bean to MetricsConfig, we can now run this application and see metrics in the console.

Stub Areas

1. Added Stub generation

2. Enhanced Stub generation by generating some stubs through unit tests

H2 Areas

1. Following H2 introduction at http://www.springboottutorial.com/spring-boot-and-h2-in-memory-database

   Including access to http://localhost:8090/h2-console connecting to jdbc:h2:mem:testdb

2. Added spring data rest to test out retrieval

Links

• https://www.callicoder.com/spring-boot-actuator/
• https://docs.spring.io/spring-boot/docs/current/reference/html/production-ready-metrics.html
• https://micrometer.io/docs/guide/healthAsGauge
• https://stackoverflow.com/questions/50193287/exporting-metrics-to-files-when-using-spring-boot-2-0