Metering your services

Instrumentation is important for cloud applications. Your service should expose health check and metrics so that it can be monitored better. Spring Boot allows for easier instrumentation through the actuator module.

Include the following in your POM:

    <dependency> 
        <groupId>org.springframework.boot</groupId> 
        <artifactId>spring-boot-starter-actuator</artifactId> 
    </dependency> 

Run the service. During startup, you will see a number of mappings being created.

You can access these URLs (such as http://localhost:8080/env) directly and see the information displayed:

{ 
  "profiles": [], 
  "server.ports": { 
    "local.server.port": 8082 
  }, 
  "commandLineArgs": { 
    "env": "dev/" 
  }, 
  "servletContextInitParams": {}, 
  "systemProperties": { 
    "java.runtime.name": "Java(TM) SE Runtime Environment", 
    "sun.boot.library.path": "C:\Program Files\Java\jdk1.8.0_73\jrebin", 
    "java.vm.version": "25.73-b02", 
    "java.vm.vendor": "Oracle Corporation", 
    "java.vendor.url": "http://java.oracle.com/", 
    "path.separator": ";", 
    "java.vm.name": "Java HotSpot(TM) 64-Bit Server VM", 
    "file.encoding.pkg": "sun.io", 
    "user.country": "IN", 
    "user.script": "", 
    "sun.java.launcher": "SUN_STANDARD", 
    "sun.os.patch.level": "Service Pack 1", 
    "PID": "9332", 
    "java.vm.specification.name": "Java Virtual Machine Specification", 
    "user.dir": "C:\Apps\wkneon\product", 

The metrics are especially interesting (http://localhost:8080/metrics):

{ 
  "mem": 353416, 
  "mem.free": 216921, 
  "processors": 4, 
  "instance.uptime": 624968, 
  "uptime": 642521, 
... 
  "gauge.servo.response.dev.product.id": 5, 
... 
   threads.peak": 38, 
  "threads.daemon": 35, 
  "threads.totalStarted": 45, 
  "threads": 37, 
... 

The information includes the counters and gauges which store the number of times the service was accessed and the response times.