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

Prerequisites

Demo

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

Procedure

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

flow

Step 1: Instrument a JVM application

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

  1. Add the 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 demo project.

  3. Configure the port and endpoint that are used to access Prometheus Service 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 demo 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 demo 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 on-premises temporary Docker image>:<Version number of the on-premises 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 on-premises temporary Docker image>:<Version number of the on-premises 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 Alibaba Cloud Container Service for Kubernetes 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 JVM 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
      Example: 
      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 Deployments page displays the created container group. Container group
  5. Create a service.
    1. In the left-side navigation pane, choose Services and Ingresses > 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 Services page displays the created service. Service

Step 4: Configure service discovery

To configure service discovery of Prometheus Service to receive data from the JVM application, perform the following steps:

  1. Log on to the ARMS console.
  2. In the left-side navigation pane, click Prometheus Monitoring.
  3. In the top navigation bar of the Prometheus Monitoring page, select the region where the ACK cluster resides. Find the cluster and click Settings in the Actions column.
  4. On the Settings page, click the Service Discovery tab. On the Service Discovery tab, click the ServiceMonitor tab.
  5. On the ServiceMonitor tab, click Add ServiceMonitor.
  6. In the Add ServiceMonitor dialog box, enter the following code and click OK: 
    apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  # Enter a unique name.
  name: tomcat-demo
  # Enter a namespace.
  namespace: default
spec:
  endpoints:
  - interval: 30s
    # Enter the value of the Name field for Port of Prometheus Exporter in the service.yaml file.
    port: tomcat-monitor
    # Enter the value of the Path field for Prometheus Exporter.
    path: /metrics
  namespaceSelector:
    any: true
    # The namespace of demo.
  selector:
    matchLabels:
      # Enter the value of the Label field in the service.yaml file to find the service.yaml file.
      app: tomcat
    The ServiceMonitor tab displays the configured service discovery task. Service discovery