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Version: Cloud

Monitor Java Application in Kubernetes

Overview​

Java applications running in Kubernetes can be monitored in SnappyFlow using two approaches:

Java monitoring with sfKubeAgent​

In this option, the Java application should be run with Jolokia agent and sfKubeAgent running as a sidecar container and fetches metrics via Jolokia port. Refer to sfKubeAgent Overview

Prerequisites​

  • Copy Jolokia JAR into docker image

  • Run the java application with Jolokia JAR in docker image:

    -javaagent:/<path_jolokia_jar>/jolokia-jvm-<version>-agent.jar

Configurations​

Run sfKubeAgent with JVMJolokia plugin, which is specified using the config map shown below: 

apiVersion: v1 
kind: ConfigMap 
metadata: 
name: jvm-configmap 
data: 
config.yaml: |- 
key: <profile_key> 
metrics: 
plugins: 
name: jvmjolokia 
enabled: true 
interval: 300 config: 
ip: 127.0.0.1 
protocol: http 
port: <userDefinedJolokiaPort> 
context: jolokia 
monitorDeadlocks: false 
deadLockMonitoringInterval: 300

The example illustrates instantiating sfKubeAgent with jvm-configmap. sfAKubeAgent talks to the Java application via userDefinedJolokiaPort (this example used 8778) 

kind: Pod 
apiVersion: v1 
metadata: 
name: my-first-pod-1 
labels: 
snappyflow/appname: <app_name> 
snappyflow/projectname: <project_name> 
spec:
containers: 
name: java-container 
image: <docker_id>/<docker_image>:<tag> ports: 
name: jolokiaport 
containerPort: <userDefinedJolokiaPort> 
Snappyflow's sfkubeagent container 
name: java-sfagent 
image: snappyflowml/sfagent:latest 
imagePullPolicy: Always command: 
/app/sfagent 
-enable-console-log 
env: 
name: APP_NAME 
value: <app_name> 
name: PROJECT_NAME 
value: <project_name> 
volumeMounts: 
name: configmap-jvm 
mountPath: /opt/sfagent/config.yaml 
subPath: config.yaml 
volumes: 
name: configmap-jvm configMap: 
name: jvm-configmap

Viewing data and dashboards​

  • Data generated by plugin can be viewed in browse data page inside the respective application under plugin=jvm_jolokia and documentType=jvm
  • Dashboard for this data can be instantiated by Importing dashboard template JVM to the application dashboard

Troubleshooting​

  1. Check if the Jolokia port is accessible

    From inside the application container, run a curl command to the userDefinedJolokiaPort.

    curl http://localhost:<userDefinedJolokiaPort>

  2. Check the logs in sfKubeAgent container for any errors

JVM Monitoring with Prometheus exporter​

Refer to Prometheus Exporter Overview. Prometheus exporter is deployed as a sidecar container in the application pod and connects to the JMX target exposed by the application to scrape the metrics. sfPod polls Prometheus exporter to scrape the metrics.

Pre-requisites​

sfPod can access Prometheus exporter at Service IP: userDefinedPrometheusPort

Configurations​

  • Run Java application with JMX options: 

    -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port= <userDefinedJMXPort> -Dcom.sun.management.jmxremote.authenticate=false - Dcom.sun.management.jmxremote.ssl=false

  • Start the Prometheus exporter with

    java -jar jmx_prometheus_httpserver.jar <userDefinedPrometheusPort> <exporterConfigFile>

    Configurations are passed using config map:

    apiVersion: v1 
    kind: ConfigMap 
    metadata: 
    labels: 
    snappyflow/appname: <app_name> 
    snappyflow/projectname: <project_name> 
    data: 
    jmx-config.yaml: | 
    --- 
    jmxUrl: service:jmx:rmi:///jndi/rmi://127.0.0.1:<userDefinedJMXPort>/jmxrmi 
    ssl: false 
    rules: 
    - pattern: '.*'

  • Prometheus exporter interfaces to JMX via userDefinedJMXPort. Example below uses 555S as the port.

  • Prometheus exporter exposes userDefinedPrometheusPort for scraping. Example uses 5556 as the port

  • Pod definition YAML that illustrates the configuration for Java application and exporter 

    kind: Pod 
    apiVersion: v1 
    metadata: 
     name: my-first-pod 
    labels: 
    snappyflow/appname: <app_name> 
    snappyflow/projectname: <project_name> 
    spec: 
    containers: 
    name: app-container 
    image: <docker_id>/<docker_image>:<tag> command: 
    sh 
    -c 
    -x 
    java -jar -Dcom.sun.management.jmxremote - Dcom.sun.management.jmxremote.port=<userDefinedJMXPort> - Dcom.sun.management.jmxremote.authenticate=false - Dcom.sun.management.jmxremote.ssl=false <application_jar> 
    name: "exporter-container" 
    image: "bitnami/jmx-exporter:latest" imagePullPolicy: 
    command: 
    sh 
    -c 
    -x 
    java -jar jmx_prometheus_httpserver.jar <userDefinedPrometheusPort> /tmp/jmx-config.yaml 
    ports: 
    name: exporter-port 
    containerPort: <userDefinedPrometheusPort> 
    volumeMounts: 
    name: configmap-jmx 
    mountPath: /tmp 
    volumes: 
    name: configmap-jmx configMap: 
    name: jmx-configmap

Viewing data and dashboards​

  • Data generated by plugin can be viewed in “browse data” page inside the respective application under plugin=‘kube-prom-jmx‘ and documentType=‘jmxStats’
  • Dashboard for this data can be instantiated by Importing dashboard template “JVM” to the application dashboard.

Troubleshooting​

  1. Check if the JMX port is accessible .From inside the application container, run a curl command to the userDefinedJMXPort.

    curl http://localhost:<userDefinedJMXPort>

  2. Check if metrics are getting scraped. From inside the exporter container, run a curl command to the userDefinedPrometheusPort

    curl  http://localhost:<userDefinedPrometheusPort>/metrics