luc.run

Exercise

Create a file named whoami.yaml that specifies a Pod named whoami with a single container based on the image: containous/whoami
Launch the Pod
Get the existing Pods and make sure the Pod named whoami is listed.
Get the Pod’s details and find the information indicating it’s IP address.
Using kubectl port-forward send a request to the application running in the whoami Pod.
Delete the Pod

Solution

The Pod’s specification is the following one:

apiVersion: v1             
kind: Pod                  
metadata:
  name: whoami
spec:
  containers:
  - name: whoami
    image: containous/whoami

The Pod can be created with the following command:

kubectl apply -f whoami.yaml

The following command list the existing Pods:

kubectl get pods

The Pod whoami should appear as Running:

NAME      READY     STATUS    RESTARTS   AGE
whoami    1/1       Running   0          14s
...

Note: pod (singular) or po can also be used as shortcuts of pods

$ kubectl get pod
NAME      READY     STATUS    RESTARTS   AGE
whoami    1/1       Running   0          16s

$ kubectl get po
NAME      READY     STATUS    RESTARTS   AGE
whoami    1/1       Running   0          22s

The Pod’s details can be retrieved with the following command:

kubectl describe pod whoami

You’ll get an output similar to this one (in this example, the Pod’s IP address is 192.168.117.160):

Name:         whoami
Namespace:    default
Priority:     0
Node:         pool-0c6fd-ertzi/194.182.169.185
Start Time:   Mon, 21 Mar 2022 20:27:00 +0100
Labels:       <none>
Annotations:  cni.projectcalico.org/containerID: bf1482441187f92742b1485b6497e92af2b28398f9c2eaa4dc21776f5213af83
              cni.projectcalico.org/podIP: 192.168.117.160/32
              cni.projectcalico.org/podIPs: 192.168.117.160/32
              kubernetes.io/psp: privileged
Status:       Running
IP:           192.168.117.160
IPs:
  IP:  192.168.117.160
Containers:
  whoami:
    Container ID:   containerd://6b53f5f5945cef71c8fd40fc15edcd61a2682f092ea84ad3be08c9d59f448c68
    Image:          containous/whoami
    Image ID:       docker.io/containous/whoami@sha256:7d6a3c8f91470a23ef380320609ee6e69ac68d20bc804f3a1c6065fb56cfa34e
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Mon, 21 Mar 2022 20:27:04 +0100
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-k5t8q (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  kube-api-access-k5t8q:
    Type:                    Projected (a volume that contains injected data from multiple sources)
    TokenExpirationSeconds:  3607
    ConfigMapName:           kube-root-ca.crt
    ConfigMapOptional:       <nil>
    DownwardAPI:             true
QoS Class:                   BestEffort
Node-Selectors:              <none>
Tolerations:                 node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                             node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
  Type    Reason     Age   From               Message
  ----    ------     ----  ----               -------
  Normal  Scheduled  60s   default-scheduler  Successfully assigned default/whoami to pool-0c6fd-ertzi
  Normal  Pulling    59s   kubelet            Pulling image "containous/whoami"
  Normal  Pulled     56s   kubelet            Successfully pulled image "containous/whoami" in 2.857153773s
  Normal  Created    56s   kubelet            Created container whoami
  Normal  Started    56s   kubelet            Started container whoami

Note: the following commands can also be used to describe the Pod whoami:

kubectl describe pods whoami
kubectl describe po whoami
kubectl describe pods/whoami
kubectl describe pod/whoami
kubectl describe po/whoami

The whole Pod’s specification can be retrieved with the following command using the -o yaml flag:

kubectl get po/whoami -o yaml

You’ll get a result like the one below:

apiVersion: v1
kind: Pod
metadata:
  annotations:
    cni.projectcalico.org/containerID: bf1482441187f92742b1485b6497e92af2b28398f9c2eaa4dc21776f5213af83
    cni.projectcalico.org/podIP: 192.168.117.160/32
    cni.projectcalico.org/podIPs: 192.168.117.160/32
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{},"name":"whoami","namespace":"default"},"spec":{"containers":[{"image":"containous/whoami","name":"whoami"}]}}
    kubernetes.io/psp: privileged
  creationTimestamp: "2022-03-21T19:27:00Z"
  name: whoami
  namespace: default
  resourceVersion: "1792248914"
  uid: cb52024e-5d56-414e-9547-bdce7b9b7ff8
spec:
  containers:
  - image: containous/whoami
    imagePullPolicy: Always
    name: whoami
    resources: {}
    terminationMessagePath: /dev/termination-log
    terminationMessagePolicy: File
    volumeMounts:
    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: kube-api-access-k5t8q
      readOnly: true
  dnsPolicy: ClusterFirst
  enableServiceLinks: true
  nodeName: pool-0c6fd-ertzi
  preemptionPolicy: PreemptLowerPriority
  priority: 0
  restartPolicy: Always
  schedulerName: default-scheduler
  securityContext: {}
  serviceAccount: default
  serviceAccountName: default
  terminationGracePeriodSeconds: 30
  tolerations:
  - effect: NoExecute
    key: node.kubernetes.io/not-ready
    operator: Exists
    tolerationSeconds: 300
  - effect: NoExecute
    key: node.kubernetes.io/unreachable
    operator: Exists
    tolerationSeconds: 300
  volumes:
  - name: kube-api-access-k5t8q
    projected:
      defaultMode: 420
      sources:
      - serviceAccountToken:
          expirationSeconds: 3607
          path: token
      - configMap:
          items:
          - key: ca.crt
            path: ca.crt
          name: kube-root-ca.crt
      - downwardAPI:
          items:
          - fieldRef:
              apiVersion: v1
              fieldPath: metadata.namespace
            path: namespace
status:
  conditions:
  - lastProbeTime: null
    lastTransitionTime: "2022-03-21T19:27:00Z"
    status: "True"
    type: Initialized
  - lastProbeTime: null
    lastTransitionTime: "2022-03-21T19:27:04Z"
    status: "True"
    type: Ready
  - lastProbeTime: null
    lastTransitionTime: "2022-03-21T19:27:04Z"
    status: "True"
    type: ContainersReady
  - lastProbeTime: null
    lastTransitionTime: "2022-03-21T19:27:00Z"
    status: "True"
    type: PodScheduled
  containerStatuses:
  - containerID: containerd://6b53f5f5945cef71c8fd40fc15edcd61a2682f092ea84ad3be08c9d59f448c68
    image: docker.io/containous/whoami:latest
    imageID: docker.io/containous/whoami@sha256:7d6a3c8f91470a23ef380320609ee6e69ac68d20bc804f3a1c6065fb56cfa34e
    lastState: {}
    name: whoami
    ready: true
    restartCount: 0
    started: true
    state:
      running:
        startedAt: "2022-03-21T19:27:04Z"
  hostIP: 194.182.169.185
  phase: Running
  podIP: 192.168.117.160
  podIPs:
  - ip: 192.168.117.160
  qosClass: BestEffort
  startTime: "2022-03-21T19:27:00Z

The Pod’s IP address can be retrieved in .status.podIP

Run the following command to open a local port mapped to the Pod’s container port:

kubectl port-forward whoami 8888:80

From your web browser, open the URL http://localhost:8888, you should get a reply similar to the following one:

Hostname: whoami
IP: 127.0.0.1
IP: ::1
IP: 192.168.117.160
IP: fe80::b866:55ff:fe79:3cf2
RemoteAddr: 127.0.0.1:58882
GET / HTTP/1.1
Host: localhost:8888
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.51 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Accept-Encoding: gzip, deflate, br
Accept-Language: fr-FR,fr;q=0.9,en-US;q=0.8,en;q=0.7
Cache-Control: max-age=0
Connection: keep-alive
If-None-Match: "5d52db33-264"
Sec-Fetch-Dest: document
Sec-Fetch-Mode: navigate
Sec-Fetch-Site: none
Sec-Fetch-User: ?1
Sec-Gpc: 1
Upgrade-Insecure-Requests: 1

The Pod can be deleted with the following command:

kubectl delete po/whoami