The metrics endpoint shows some of the important metrics pertaining to the following:

• Server: Free memory, processors, uptime, and so on
• JVM: Details about the heap, threads, garbage collection, sessions, and so on
• Responses provided by application services

An extract from the response of the /actuator/metrics endpoint is as follows:

{
   "names":[
      "jvm.memory.max",
      "jvm.threads.states",
      "http.server.requests",
      //Lot of other values
      "tomcat.global.received",
      "process.uptime",
      "tomcat.sessions.rejected",
      "process.cpu.usage",
      //Lot of other values
      "process.start.time"
   ]
}

The metrics service returns the list of metrics. To get a specific metric value, you would need to use the /actuator/metrics/{METRIC-NAME} URI. {METRIC-NAME} should be replaced by the appropriate name from the preceding response.

For example, the /actuator/metrics/jvm.memory.max URI will return the following response:

{
  "name": "jvm.memory.max",
  "description": "The maximum amount of memory in bytes that can be used for memory management",
  "baseUnit": "bytes",
  "measurements": [{
      "statistic": "VALUE",
      "value": 5600444415
    }],
  "availableTags": [{
      "tag": "area",
      "values": ["heap", "nonheap"]
    }, {
      "tag": "id",
      "values": ["Compressed Class Space", "PS Survivor Space", "PS Old Gen", "Metaspace", "PS Eden Space", "Code Cache"]
    }]
}