Kubernetes Cluster Application Using SkyWalking to Collect Tracing Data¶

Introduction¶

In a Kubernetes cluster, applications are deployed in the form of images. When using SkyWalking to collect application tracing data, if you follow the traditional method of embedding the SkyWalking Agent into each application image before deployment, it will result in bloated images and make future upgrades of SkyWalking versions inconvenient. This article introduces a method that uses the official SkyWalking image with initContainers to provide the SkyWalking Agent for the application to collect tracing data.

Prerequisites¶

Install DataKit¶

DataKit>
DataKit version >= 1.4.15

Enable Input¶

Enable the Skywalking collector by adding the /usr/local/datakit/conf.d/skywalking/skywalking.conf file on the server where DataKit is located. When deploying via DaemonSet, you need to define a ConfigMap first and then mount the file into the DataKit container. The following steps will require the datakit.yaml used during the DataKit deployment.

Define skywalking.conf¶

Add the definition of skywalking.conf in the ConfigMap resource section of the datakit.yaml file.

apiVersion: v1
kind: ConfigMap
metadata:
  name: datakit-conf
  namespace: datakit
data:  
    ## Below is the new content
    skywalking.conf: |- 
        [[inputs.skywalking]]
          ## skywalking grpc server listening on address
          address = "0.0.0.0:11800"

Mount skywalking.conf¶

Add the following content under the volumeMounts section of the datakit.yaml file.

        - mountPath: /usr/local/datakit/conf.d/skywalking/skywalking.conf
          name: datakit-conf
          subPath: skywalking.conf

Restart DataKit¶

kubectl delete -f datakit.yaml
kubectl apply -f datakit.yaml

Java Tracing Data Integration¶

Write Test Application¶

The example uses datakit-springboot-demo. After downloading, create a jar file named service-demo-1.0-SNAPSHOT.jar.

Create Image¶

Write a Dockerfile.

FROM openjdk:8u292

RUN /bin/cp /usr/share/zoneinfo/Asia/Shanghai /etc/localtime
RUN echo 'Asia/Shanghai' >/etc/timezone
ENV jar service-demo-1.0-SNAPSHOT.jar

ENV workdir /data/app/
RUN mkdir -p ${workdir}
COPY ${jar} ${workdir}
WORKDIR ${workdir}
ENTRYPOINT ["sh", "-ec", "exec java ${JAVA_OPTS} -jar ${jar} ${PARAMS} "]

Create the image and upload it to the image repository.

docker build -t 172.16.0.246/df-demo/service-demo:v1 .
docker push 172.16.0.246/df-demo/service-demo:v1

Deploy Application¶

In the skywalking-demo.yaml file used for application deployment, use initContainers to initialize the apache/skywalking-java-agent:8.7.0-alpine image. Applications within the same Pod can access the skywalking-agent.jar. Then define the startup command in JAVA_OPTS, where -Dskywalking.agent.service_name=skywalking-demo-master defines the alias of the application as skywalking-demo-master.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: skywalking-demo-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      app: skywalking-demo-pod
  template:
    metadata:
      labels:
        app: skywalking-demo-pod
      annotations:
    spec:
      containers:
      - name: skywalking-demo-demo-container
        image: 172.16.0.246/df-demo/service-demo:v1
        env:
        - name: HOST_IP
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: status.hostIP
        - name: HOST_NAME
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: spec.nodeName      
        - name: JAVA_OPTS
          value: |-
                -javaagent:/skywalking/agent/skywalking-agent.jar -Dskywalking.agent.service_name=skywalking-demo-master  -Dskywalking.collector.backend_service=$(HOST_IP):11800           
        ports:
        - containerPort: 8090
          protocol: TCP
        volumeMounts:
        - mountPath: /skywalking
          name: skywalking-agent
      initContainers:
        - name: agent-container
          image: apache/skywalking-java-agent:8.7.0-alpine
          volumeMounts:
            - name: skywalking-agent   
              mountPath: /agent
          command: [ "/bin/sh" ]
          args: [ "-c", "cp -R /skywalking/agent /agent/" ]  
      restartPolicy: Always
      volumes:
        - name: skywalking-agent
          emptyDir: {}

kubectl apply -f skywalking-demo.yaml

Access Application¶

Check the pod port.

Call the application to generate tracing data.

curl 10.244.36.98:8090/ping

Application Performance Monitoring¶

Log in to ‘Guance’, go to the ‘APM’ module, and view the skywalking-demo-master application.