Super Simple Spring Cloud - Actuator

Jul 30, 2019

 common  java  Spring  Cloud  Microservice  Actuator

Acuator is tools that can be used to monitoring your application’s health status. The official guide is here:

https://docs.spring.io/spring-boot/docs/current/reference/html/production-ready-features.html#production-ready

Spring Cloud family:

Component name Function Description
Spring Actuator Monitor your application’s health
Eureka/Zookeeper Service Registration provider(for Service Discovery)
Ribbon Load Balancer (for service)
Feign (Client) replacement of RestTemplate/Web Client
Hystrix isolate failed service
Spring Cloud Gateway Microservice Gateway
Spring Cloud Config Externalized Config
Spring Cloud Slueth Provide (Services) Distributed Tracing

Spring Actuator

Once you added the actuator package in dependencies either in Maven or Gradle, your application is actuator enabled. The link below will show once your application started: http://localhost:8079/actuator/health, it will tell you status = up…

The health is called technology-agnostic endpoints, the full list is here

**In Spring Boot 1.x Actuator disabled most of endpoint, only /health and /info are available.

to enable all the endpoints, you need add following line application.yml, it enable all the endpoints.

management:
  endpoints:
    web:
      exposure:
        # open all the monitor points
        include: '*'
  endpoint:
    health:
      # display all the health indicators
      show-details: always

But I think following endpoints is most useful: health – basic information about the service. the Default health only provide status = ok those non-sense message, if you want more detail message, add following in application.yml, under the management section

  endpoint:
    health:
      # display all the health indicators
      show-details: always

env – information about OS, JVM and etc. mappings – show all the @RequestMappging path threaddump – show thread dump of the JVM, quick diagnose if you can’t log on production machine.

httptrace – in Spring boots 1.2.x and up, this function need to manually add an InMemoryHttpTraceRepository in @Configuration class:

    @Bean
    public HttpTraceRepository htttpTraceRepository(){
        return new InMemoryHttpTraceRepository();
    }

metrics and metrics/{metrics name} – metrics is very useful endpoints but it take 1 steps: 0.Get metrics list: http://localhost:8080/actuator/metrics

{
  "names": [
    "hikaricp.connections",
    "hikaricp.connections.acquire",
    "hikaricp.connections.active",
    "hikaricp.connections.creation",
    "hikaricp.connections.idle",
    "hikaricp.connections.max",
    "hikaricp.connections.min",
    "hikaricp.connections.pending",
    "hikaricp.connections.timeout",
    "hikaricp.connections.usage",
    "http.server.requests",
    "jdbc.connections.active",
    "jdbc.connections.idle",
    "jdbc.connections.max",
    "jdbc.connections.min",
    "jvm.buffer.count",
    "jvm.buffer.memory.used",
    "jvm.buffer.total.capacity",
    "jvm.classes.loaded",
    "jvm.classes.unloaded",
    "jvm.gc.live.data.size",
    "jvm.gc.max.data.size",
    "jvm.gc.memory.allocated",
    "jvm.gc.memory.promoted",
    "jvm.gc.pause",
    "jvm.memory.committed",
    "jvm.memory.max",
    "jvm.memory.used",
    "jvm.threads.daemon",
    "jvm.threads.live",
    "jvm.threads.peak",
    "jvm.threads.states",
    "logback.events",
    "process.cpu.usage",
    "process.start.time",
    "process.uptime",
    "system.cpu.count",
    "system.cpu.usage",
    "tomcat.sessions.active.current",
    "tomcat.sessions.active.max",
    "tomcat.sessions.alive.max",
    "tomcat.sessions.created",
    "tomcat.sessions.expired",
    "tomcat.sessions.rejected"
  ]
}

1.use the item in this list eg jvm.memory.used to see current JVM memory usage:

{
  "name": "jvm.memory.used",
  "description": "The amount of used memory",
  "baseUnit": "bytes",
  "measurements": [
    {
      "statistic": "VALUE",
      "value": 138291399
    }
  ],
  "availableTags": [
    {
      "tag": "area",
      "values": [
        "heap",
        "nonheap"
      ]
    },
    {
      "tag": "id",
      "values": [
        "CodeHeap 'profiled nmethods'",
        "G0 Old Gen",
        "CodeHeap 'non-profiled nmethods'",
        "G0 Survivor Space",
        "Compressed Class Space",
        "Metaspace",
        "G0 Eden Space",
        "CodeHeap 'non-nmethods'"
      ]
    }
  ]
}

finally, this is the full content of my application.yml:

server:
  port: 8079
spring:
  jpa:
    # pring SQL in hibernate
    show-sql: true
logging:
  level:
    root: INFO
    # hibernate logging setting
    org.hibernate: INFO
    org.hibernate.type.descriptor.sql.BasicBinder: TRACE
    org.hibernate.type.descriptor.sql.BasicExtractor: TRACE
management:
  endpoints:
    web:
      exposure:
        # open all the monitor points
        include: '*'
  endpoint:
    health:
      # display all the health indicators
      show-details: always
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