Pod in Deployment won't fulfill readiness check

Question

I made a simple deployment of an nginx pod and afterwards edited the deployment to add a readinessProbe and a livenessProbe via TCP like in the official docs.

Once I save it the deployment created a new replicaSet and started the new pod, but the probes never get fulfilled.

Here is the deployment yaml output of the describe command:

apiVersion: apps/v1
kind: Deployment
metadata:
  annotations:
    deployment.kubernetes.io/revision: "2"
  creationTimestamp: "2020-09-21T18:51:13Z"
  generation: 2
  labels:
    app: dep1
  name: dep1
  namespace: default
  resourceVersion: "1683893"
  selfLink: /apis/apps/v1/namespaces/default/deployments/dep1
  uid: b23bceff-aca5-4c89-84c0-5882cf2df217
spec:
  progressDeadlineSeconds: 600
  replicas: 1
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: dep1
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
    type: RollingUpdate
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: dep1
    spec:
      containers:
      - image: nginx
        imagePullPolicy: Always
        livenessProbe:
          failureThreshold: 3
          initialDelaySeconds: 15
          periodSeconds: 20
          successThreshold: 1
          tcpSocket:
            port: 8080
          timeoutSeconds: 1
        name: nginx
        ports:
        - containerPort: 8080
          protocol: TCP
        readinessProbe:
          failureThreshold: 3
          initialDelaySeconds: 5
          periodSeconds: 10
          successThreshold: 1
          tcpSocket:
            port: 8080
          timeoutSeconds: 1
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30
status:
  availableReplicas: 1
  conditions:
  - lastTransitionTime: "2020-09-21T18:51:16Z"
    lastUpdateTime: "2020-09-21T18:51:16Z"
    message: Deployment has minimum availability.
    reason: MinimumReplicasAvailable
    status: "True"
    type: Available
  - lastTransitionTime: "2020-09-21T18:51:13Z"
    lastUpdateTime: "2020-09-21T19:16:07Z"
    message: ReplicaSet "dep1-5d66c67794" is progressing.
    reason: ReplicaSetUpdated
    status: "True"
    type: Progressing
  observedGeneration: 2
  readyReplicas: 1
  replicas: 2
  unavailableReplicas: 1
  updatedReplicas: 1

And here are the events of the pod:

Events:
  Type     Reason     Age                     From                     Message
  ----     ------     ----                    ----                     -------
  Normal   Scheduled  <unknown>               default-scheduler        Successfully assigned default/dep1-5d66c67794-qd48q to docker-desktop
  Normal   Pulling    13m (x2 over 14m)       kubelet, docker-desktop  Pulling image "nginx"
  Normal   Killing    13m                     kubelet, docker-desktop  Container nginx failed liveness probe, will be restarted
  Normal   Pulled     13m (x2 over 14m)       kubelet, docker-desktop  Successfully pulled image "nginx"
  Normal   Created    13m (x2 over 14m)       kubelet, docker-desktop  Created container nginx
  Normal   Started    13m (x2 over 14m)       kubelet, docker-desktop  Started container nginx
  Warning  Unhealthy  12m (x5 over 14m)       kubelet, docker-desktop  Liveness probe failed: dial tcp 10.1.0.174:8080: connect: connection refused
  Warning  Unhealthy  9m48s (x30 over 14m)    kubelet, docker-desktop  Readiness probe failed: dial tcp 10.1.0.174:8080: connect: connection refused
  Warning  BackOff    4m42s (x11 over 8m36s)  kubelet, docker-desktop  Back-off restarting failed container

Why is the connection refused when I opened the ports with the following?

ports:
  - containerPort: 8080
    protocol: TCP

Answer 1

By default, nginx webserver exposes the port 80, not just your health checks aren't working but your application will never open on port 8080. The docker image used in this tutorial is k8s.gcr.io/goproxy:0.1, you are using nginx. Try this config or change your image deployment to k8s.gcr.io/goproxy:0.1:

spec:
  containers:
  - image: nginx
    imagePullPolicy: Always
    livenessProbe:
      failureThreshold: 3
      initialDelaySeconds: 15
      periodSeconds: 20
      successThreshold: 1
      tcpSocket:
        port: 80
      timeoutSeconds: 1
    name: nginx
    ports:
    - containerPort: 80
      protocol: TCP
    readinessProbe:
      failureThreshold: 3
      initialDelaySeconds: 5
      periodSeconds: 10
      successThreshold: 1
      tcpSocket:
        port: 80
      timeoutSeconds: 1