5. Pods

Pods are the smallest unit of computing in Kubernetes. A pod contains one or more containers with shared storage and network resources.

5.1. Example: a Nginx pod

The following YAML file defines a Nginx pod:

kubectl run nginx-pod --image=nginx:1.27.0-bookworm --port=80 \
--dry-run=client -o yaml | tee nginx-pod.yaml | yq

nginx-pod.yaml

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: nginx-pod
  name: nginx-pod
spec:
  containers:
    - image: nginx:1.27.0-bookworm
      name: nginx-pod
      ports:
        - containerPort: 80
      resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

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5.2. Launching the pod

We can create the nginx-pod using kubectl create or kubectl apply.

Command	Object does not exist	Object exists
create	Creates new object	Error
apply	Creates new object (needs complete spec)	Configure object (accepts partial spec)
replace	Error	Delete object; create new object

$ kubectl create -f nginx-pod.yaml
pod/nginx-pod created

We can also use kubectl to inspect the newly created pod:

$ kubectl get pods
NAME        READY   STATUS    RESTARTS   AGE
nginx-pod   1/1     Running   0          21s

$ kubectl get pod nginx-pod -o yaml | yq -C | less -R  # force color with CLI flags

$ kubectl describe pod nginx-pod | grep "Events:" -A 15
Events:
  Type    Reason     Age    From               Message
  ----    ------     ----   ----               -------
  Normal  Scheduled  5m51s  default-scheduler  Successfully assigned default/nginx-pod to minikube
  Normal  Pulling    5m50s  kubelet            Pulling image "nginx:1.27.0-bookworm"
  Normal  Pulled     5m45s  kubelet            Successfully pulled image "nginx:1.27.0-bookworm" in 5.019s (5.019s including waiting). Image size: 187603368 bytes.
  Normal  Created    5m45s  kubelet            Created container nginx-pod
  Normal  Started    5m45s  kubelet            Started container nginx-pod

5.3. Port forwarding

To access our new nginx-pod server:

$ kubectl port-forward --address 0.0.0.0,:: pod/nginx-pod 8000:80
Forwarding from 0.0.0.0:8000 -> 80
Forwarding from [::]:8000 -> 80
Handling connection for 8000

Note that the --address flag is only needed if remote access is desired (default is localhost).

5.4. Deleting the pod

$ kubectl delete pod nginx-pod
pod "nginx-pod" deleted