To monitor a Java virtual machine (JVM) application by using Managed Service for Prometheus, you can instrument the JVM application to expose data, use Managed Service for Prometheus to collect data, configure a Grafana dashboard to display the data, and then create alert rules. This topic describes how to use Managed Service for Prometheus to monitor a JVM application. In this example, Container Service for Kubernetes (ACK) and Container Registry are used.

Prerequisites

Sample project

You can also use a sample project to learn how to monitor a JVM application by using Managed Service for Prometheus. For more information about the sample project, visit GitHub.

Procedure

The following figure shows the process of using Managed Service for Prometheus to monitor a JVM application.

Flowchart

Step 1: Instrument a JVM application

To instrument a JVM application to expose data, perform the following steps:

  1. Add Maven dependencies to the pom.xml file.
    <dependency>
        <groupId>io.prometheus</groupId>
        <artifactId>simpleclient_hotspot</artifactId>
        <version>0.6.0</version>
    </dependency>
  2. Add the method to initialize the JVM exporter to the application code.
    @PostConstruct
        public void initJvmExporter() {
            io.prometheus.client.hotspot.DefaultExports.initialize();
        }

    For more information, see the /src/main/java/com/monitise/prometheus_demo/DemoController.java file of the sample project.

  3. Configure the port number and path that are used for Managed Service for Prometheus in the application.properties file.
    management.port: 8081
    endpoints.prometheus.path: prometheus-metrics

    For more information, see the /src/main/resources/application.properties file of the sample project.

  4. Add the method to enable the HTTP port to the application code.
    @SpringBootApplication
    // sets up the prometheus endpoint /prometheus-metrics
    @EnablePrometheusEndpoint
    // exports the data at /metrics at a prometheus endpoint
    @EnableSpringBootMetricsCollector
    public class PrometheusDemoApplication {
        public static void main(String[] args) {
            SpringApplication.run(PrometheusDemoApplication.class, args);
        }
    }

    For more information, see the /src/main/java/com/monitise/prometheus_demo/PrometheusDemoApplication.java file of the sample project.

Step 2: Upload the JVM application

To build an image for the instrumented JVM application and upload the image to an image repository of Container Registry, perform the following steps:

  1. Run the following command to recompile a module:
    mvn clean install -DskipTests
  2. Run the following command to build an image:
    docker build -t <Name of the local temporary Docker image>:<Version number of the local temporary Docker image> . --no-cache
    Example:
    docker build -t promethues-demo:v0 . --no-cache
  3. Run the following command to tag the image:
    sudo docker tag <Name of the local temporary Docker image>:<Version number of the local temporary Docker image> <Domain name of the image repository>/<Namespace>/<Image name>:<Image version number>
    Example:
    sudo docker tag promethues-demo:v0 registry.cn-hangzhou.aliyuncs.com/testnamespace/promethues-demo:v0
  4. Run the following command to upload the image to the image repository:
    sudo docker push <Domain name of the image repository>/<Namespace>/<Image name>:<Image version number>
    Example:
    sudo docker push registry.cn-hangzhou.aliyuncs.com/testnamespace/promethues-demo:v0
    You can view the information about the uploaded application image on the Tags page of the Container Registry console. Image

Step 3: Deploy the JVM application

To deploy the JVM application to an ACK cluster, perform the following steps:

  1. Log on to the ACK console.
  2. In the left-side navigation pane, click Clusters.
  3. On the Clusters page, find the cluster to which you want to deploy the application and click Applications in the Actions column.
  4. Create a container group.
    1. In the left-side navigation pane, choose Workloads > Deployments.
    2. On the Deployments page, click Create from YAML in the upper-right corner.
    3. On the Create page, enter the following code in the Template code editor and click Create:
      apiVersion: apps/v1 # for versions before 1.8.0 use apps/v1beta1
      kind: Deployment
      metadata:
        name: prometheus-demo
      spec:
        replicas: 2
        template:
          metadata:
            annotations:
              prometheus.io/scrape: 'true'
              prometheus.io/path: '/prometheus-metrics'
              prometheus.io/port: '8081'
            labels:
              app: tomcat
          spec:
            containers:
            - name: tomcat
              imagePullPolicy: Always
              image: <Domain name of the image repository>/<Namespace>/<Image name>:<Image version number>
              ports:
              - containerPort: 8080
                name: tomcat-normal
              - containerPort: 8081
                name: tomcat-monitor
      Sample code:
      apiVersion: apps/v1 # for versions before 1.8.0 use apps/v1beta1
      kind: Deployment
      metadata:
        name: prometheus-demo
        labels:
          app: tomcat
      spec:
        replicas: 2
        selector:
          matchLabels:
            app: tomcat
        template:
          metadata:
            annotations:
              prometheus.io/scrape: 'true'
              prometheus.io/path: '/prometheus-metrics'
              prometheus.io/port: '8081'
            labels:
              app: tomcat
          spec:
            containers:
            - name: tomcat
              imagePullPolicy: Always
              image: registry.cn-hangzhou.aliyuncs.com/peiyu-test/prometheus-demo:v0
              ports:
              - containerPort: 8080
                name: tomcat-normal
              - containerPort: 8081
                name: tomcat-monitor
    The newly created container group is displayed on the Deployments page. Container group
  5. Create a service.
    1. In the left-side navigation pane, choose Network > Services.
    2. On the Services page, click Create Resources in YAML.
    3. On the Create page, enter the following code in the Template code editor and click Create:
      apiVersion: v1
      kind: Service
      metadata:
        labels:
          app: tomcat
        name: tomcat
        namespace: default
      spec:
        ports:
        - name: tomcat-normal
          port: 8080
          protocol: TCP
          targetPort: 8080
        - name: tomcat-monitor
          port: 8081
          protocol: TCP
          targetPort: 8081
        type: NodePort
        selector:
          app: tomcat
    The newly created Service is displayed in the Services page. Service

Step 4: Configure a service discovery task

Configure a service discovery task on the ServiceMonitor tab in Managed Service for Prometheus to collect data from the JVM application. For more information, see Use ServiceMonitors to discover and monitor Services.