4. Observability (18%)

Defining a Pod’s Readiness and Liveness Probe

  1. Create a new Pod named hello with the image bonomat/nodejs-hello-world that exposes the port 3000. Provide the name nodejs-port for the container port.

  2. Add a Readiness Probe that checks the URL path / on the port referenced with the name nodejs-port after a 2 seconds delay. You do not have to define the period interval.

  3. Add a Liveness Probe that verifies that the app is up and running every 8 seconds by checking the URL path / on the port referenced with the name nodejs-port. The probe should start with a 5 seconds delay.

  4. Shell into container and curl localhost:3000. Write down the output. Exit the container. Retrieve the logs from the container. Write down the output.

答案： Create the intial YAML with the following command.

$ kubectl run hello --image=bonomat/nodejs-hello-world --restart=Never --port=3000 -o yaml --dry-run > pod.yaml

Edit the YAML file and add the probes. 参考官网： livenessProbe

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: hello
  name: hello
spec:
  containers:
  - image: bonomat/nodejs-hello-world
    name: hello
    ports:
    - name: nodejs-port
      containerPort: 3000
    readinessProbe:
      httpGet:
        path: /
        port: nodejs-port
      initialDelaySeconds: 2
    livenessProbe:
      httpGet:
        path: /
        port: nodejs-port
      initialDelaySeconds: 5
      periodSeconds: 8
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Never
status: {}

Create the Pod from the YAML file, shell into the Pod as soon as it is running and execute the curl command.

Fixing a Misconfigured Pod

  1. Create a new Pod with the following YAML.

  1. Check the Pod’s status. Do you see any issue?

  2. Follow the logs of the running container and identify an issue.

  3. Fix the issue by shelling into the container. After resolving the issue the current date should be written to a file. Render the output.

答案： First, create the Pod with the given YAML content.

The Pod seems to be running without problems.

Render the logs of the container. The output should indicate an error message every 5 seconds.

Apparently, the directory we want to write to does not exist. Log into the container and create the directory. The file ~/tmp/curr-date.txt is populated.

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