Instrumenting a specific Kubernetes Deployment with Cluster Agent auto-instrumentation using LabelMatch Strategy

[Abhi.Bajaj]

AppDynamics Cluster Agent allows you to auto-instrument your Applications running on Kubernetes. The auto-instrumentation injects APM agents on runtime, modifying your deployment spec with an init-container of AppDynamics APM agent.

You can use different strategies to target Kubernetes deployments, StatefulSet, or DeploymentConfigs.

In this article, we will cover instrumenting one deployment by using a label defined on the Deployment level (it will be the same for DeploymentConfig and StatefulSet)

Let's take this forward with two sample deployments running in namespace abhi-java-apps-second.

My first deployment:

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: tomcat-app-abhi
  labels:
    app: tomcat-app-abhi-second
  namespace: abhi-java-apps-second
spec:
  replicas: 1
  selector:
    matchLabels:
      app: tomcat-app-abhi
  template:
    metadata:
      labels:
        app: tomcat-app-abhi
    spec:
      containers:
      - name: tomcat-app-abhi
        #image: docker.io/abhimanyubajaj98/java-tomcat-sample-app-buildx:latest
        image: docker.io/abhimanyubajaj98/java-application:latest
        imagePullPolicy: Always
        ports:
        - containerPort: 8080
        env:
        - name: JAVA_TOOL_OPTIONS
          value: -Xmx512m
        #- name: APPDYNAMICS_AGENT_UNIQUE_HOST_ID
        #  value: $(cat /proc/self/cgroup | head -1 | awk -F '/' '{print $NF}' | cut -c 16-27)
---
apiVersion: v1
kind: Service
metadata:
  name: tomcat-app-service
  labels:
    app: tomcat-app-abhi
  namespace: abhi-java-apps-second
spec:
  ports:
  - port: 8080
    targetPort: 8080
  selector:
    app: tomcat-app-abhi

My Second deployment:

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: tomcat-app-abhi-labelmatch
  labels:
    app: tomcat-app-abhi-second-labelmatch
  namespace: abhi-java-apps-second
spec:
  replicas: 1
  selector:
    matchLabels:
      app: tomcat-app-abhi-labelmatch
  template:
    metadata:
      labels:
        app: tomcat-app-abhi-labelmatch
    spec:
      containers:
      - name: tomcat-app-abhi
        #image: docker.io/abhimanyubajaj98/java-tomcat-sample-app-buildx:latest
        image: docker.io/abhimanyubajaj98/java-application:latest
        imagePullPolicy: Always
        ports:
        - containerPort: 8080
        env:
        - name: JAVA_TOOL_OPTIONS
          value: -Xmx512m
        #- name: APPDYNAMICS_AGENT_UNIQUE_HOST_ID
        #  value: $(cat /proc/self/cgroup | head -1 | awk -F '/' '{print $NF}' | cut -c 16-27)
---
apiVersion: v1
kind: Service
metadata:
  name: tomcat-app-service-labelmatch
  labels:
    app: tomcat-app-abhi-labelmatch
  namespace: abhi-java-apps-second
spec:
  ports:
  - port: 8080
    targetPort: 8080
  selector:
    app: tomcat-app-abhi-labelmatch

Now, my use case is only for instrument deployment tomcat-app-abhi-labelmatch. To do this, I would need to edit my cluster-agent.yaml and add the below specs:

instrumentationRules:
    - namespaceRegex: abhi-java-apps-second
      labelMatch:
      - app: tomcat-app-abhi-second-labelmatch
      tierName: abhiapps
      language: java
      imageInfo:
        image: "docker.io/appdynamics/java-agent:latest"
        agentMountPath: /opt/appdynamics
        imagePullPolicy: Always

Now, after the deployment is done, only the deployment tomcat-app-abhi-labelmatch will have AppDynamics Java Agent.