Pods with YAML

Ce cours explique comment créer un Pod Kubernetes à l’aide d’un fichier de configuration YAML. Vous y apprendrez à structurer le fichier YAML, à créer le Pod avec kubectl, puis à vérifier son statut afin de vous assurer qu’il fonctionne correctement.

Top-Level Fields d’un fichier YAML Kubernetes¶

Kubernetes utilise des fichiers YAML pour définir des objets tels que les Pods, ReplicaSets, Deployments, Services, etc. Ces fichiers suivent une structure standard composée de quatre champs principaux. Chaque fichier de définition Kubernetes doit inclure les champs suivants :

apiVersion:
kind:
metadata:
spec:

apiVersion: This field indicates the version of the Kubernetes API you are using. For a Pod, set apiVersion: v1. Depending on the object you define, you might need different versions such as apps/v1, extensions/v1beta1, etc.
kind: This specifies the type of object being created. In this lesson, since we're creating a Pod, you'll define it as kind: Pod. Other objects might include ReplicaSet, Deployment, or Service.
metadata: The metadata section provides details about the object, including its name and labels. It is represented as a dictionary. It is essential to maintain consistent indentation for sibling keys to ensure proper YAML nesting. For example:
spec: The spec section provides specific configuration details for the object. For a Pod, this is where you define its containers. Since a Pod can run multiple containers, the containers field is an array. In our example, with a single container, the array has just one item. The dash (-) indicates a list item, and each container must be defined with at least name and image keys.

Below is the complete YAML configuration for our Pod:

Note

Be sure to follow proper indentation rules. Use two spaces per level (avoid tabs), as misalignment can lead to errors.

pod.yaml
apiVersion: v1
kind: Pod
metadata:
  name: podinfo
  namespace: default
  labels:
    app.kubernetes.io/name: podinfo
spec:
  containers:
  - name: podinfo
    image: ghcr.io/stefanprodan/podinfo:6.11.0

Note

To add additional containers, insert another block within the containers list with the appropriate name and image.

Creating and Verifying the Pod¶

After you have saved your configuration (for example, as pod.yaml), use the following command to create the Pod:

Note

kubectl run podinfo --image=ghcr.io/stefanprodan/podinfo:6.11.0 --dry-run=client -o yaml > pod.yaml

kubectl apply -f pod.yaml

apply vs create

Utiliser la commande kubectl apply -f plutot que kubectl create -f

kubectl apply -f
- crée le Pod s’il n’existe pas
- échoue si la ressource existe déjà
kubectl create -f
- crée la ressource si elle n’existe pas
- met à jour la configuration si elle existe

Tester le manifest sans créer la ressource

kubectl apply -f pod.yaml --dry-run=client -o yaml
apiVersion: v1
kind: Pod
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{},"labels":{"app.kubernetes.io/managed-by":"kubectl","app.kubernetes.io/name":"podinfo"},"name":"podinfo","namespace":"default"},"spec":{"containers":[{"image":"ghcr.io/stefanprodan/podinfo:6.11.0","name":"podinfo"}]}}
  creationTimestamp: "2026-03-07T02:45:33Z"
  generation: 1
  labels:
    app.kubernetes.io/managed-by: kubectl
    app.kubernetes.io/name: podinfo
  name: podinfo
  namespace: default
  resourceVersion: "64366"
  uid: 8161158a-24c2-43d6-a048-91ae77fc780f
spec:
  containers:
  - image: ghcr.io/stefanprodan/podinfo:6.11.0
    imagePullPolicy: IfNotPresent
    name: podinfo
    resources: {}
    terminationMessagePath: /dev/termination-log
    terminationMessagePolicy: File
    volumeMounts:
    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: kube-api-access-psmmf
      readOnly: true
  dnsPolicy: ClusterFirst
  enableServiceLinks: true
  nodeName: test-control-plane
  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-psmmf
    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: "2026-03-07T02:45:34Z"
    observedGeneration: 1
    status: "True"
    type: PodReadyToStartContainers
  - lastProbeTime: null
    lastTransitionTime: "2026-03-07T02:45:33Z"
    observedGeneration: 1
    status: "True"
    type: Initialized
  - lastProbeTime: null
    lastTransitionTime: "2026-03-07T02:45:34Z"
    observedGeneration: 1
    status: "True"
    type: Ready
  - lastProbeTime: null
    lastTransitionTime: "2026-03-07T02:45:34Z"
    observedGeneration: 1
    status: "True"
    type: ContainersReady
  - lastProbeTime: null
    lastTransitionTime: "2026-03-07T02:45:33Z"
    observedGeneration: 1
    status: "True"
    type: PodScheduled
  containerStatuses:
  - containerID: containerd://e7f72ede38ccd52133d1a3e98d01eb313a436fd301f4302d662519f22c0ea4fe
    image: ghcr.io/stefanprodan/podinfo:6.11.0
    imageID: ghcr.io/stefanprodan/podinfo@sha256:5b789251f4b35f4ac6319c48b57eb6d29356d67471404c5fd3733db2eb8c11cf
    lastState: {}
    name: podinfo
    ready: true
    resources: {}
    restartCount: 0
    started: true
    state:
      running:
        startedAt: "2026-03-07T02:45:33Z"
    user:
      linux:
        gid: 101
        supplementalGroups:
        - 101
        uid: 100
    volumeMounts:
    - mountPath: /var/run/secrets/kubernetes.io/serviceaccount
      name: kube-api-access-psmmf
      readOnly: true
      recursiveReadOnly: Disabled
  hostIP: 172.18.0.2
  hostIPs:
  - ip: 172.18.0.2
  observedGeneration: 1
  phase: Running
  podIP: 10.244.0.8
  podIPs:
  - ip: 10.244.0.8
  qosClass: BestEffort
  startTime: "2026-03-07T02:45:33Z"

Once the Pod is created, you can verify its status by listing all Pods:

kubectl get pods -n default
NAME      READY   STATUS    RESTARTS   AGE
podinfo   1/1     Running   0          5m6s

To view detailed information about the Pod, run: This command provides extensive details, including metadata, node assignment, container specifics, and event history such as scheduling, volume mounting, and container start-up. Here is an example output:

kubectl describe pod podinfo
Name:             podinfo
Namespace:        default
Priority:         0
Service Account:  default
Node:             test-control-plane/172.18.0.2
Start Time:       Sat, 07 Mar 2026 03:45:33 +0100
Labels:           app.kubernetes.io/name=podinfo
Annotations:      <none>
Status:           Running
IP:               10.244.0.8
IPs:
  IP:  10.244.0.8
Containers:
  podinfo:
    Container ID:   containerd://e7f72ede38ccd52133d1a3e98d01eb313a436fd301f4302d662519f22c0ea4fe
    Image:          ghcr.io/stefanprodan/podinfo:6.11.0
    Image ID:       ghcr.io/stefanprodan/podinfo@sha256:5b789251f4b35f4ac6319c48b57eb6d29356d67471404c5fd3733db2eb8c11cf
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Sat, 07 Mar 2026 03:45:33 +0100
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-psmmf (ro)
Conditions:
  Type                        Status
  PodReadyToStartContainers   True
  Initialized                 True
  Ready                       True
  ContainersReady             True
  PodScheduled                True
Volumes:
  kube-api-access-psmmf:
    Type:                    Projected (a volume that contains injected data from multiple sources)
    TokenExpirationSeconds:  3607
    ConfigMapName:           kube-root-ca.crt
    Optional:                false
    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  5m33s  default-scheduler  Successfully assigned default/podinfo to test-control-plane
  Normal  Pulled     5m33s  kubelet            spec.containers{podinfo}: Container image "ghcr.io/stefanprodan/podinfo:6.11.0" already present on machine and can be accessed by the pod
  Normal  Created    5m33s  kubelet            spec.containers{podinfo}: Container created
  Normal  Started    5m33s  kubelet            spec.containers{podinfo}: Container started

Note

Using kubectl describe helps you gain detailed insights into the internal state of your Pod, which can be invaluable for troubleshooting.

Conclusion¶

In this lesson, you learned how to structure a Kubernetes YAML file for a Pod, create it using kubectl, and verify its status. This hands-on approach equips you to manage and troubleshoot your Kubernetes resources effectively. Happy Kubernetes-ing!

For more information, refer to the following resources: