Multi-container Pod design

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A sidecar supports another container in the same Pod. The containers share a network namespace, but their filesystems remain separate unless you mount a shared volume. Declare the volume once in the Pod spec and reference the same volume name from each container. Each mount can use a different path suited to that process. A missing or mismatched volume name can stop the workload from starting. Here a fictional web service and collector share an emptyDir log workspace. The tasks verify both mounts and the supporting process, so adding a second container without its data connection doesn't satisfy the design.

printf '%s' 'apiVersion: "v1"
kind: "Pod"
metadata:
  name: "cobalt-295"
spec:
  containers:
    - name: "web"
      image: "nginx:1.27"
      volumeMounts:
        - name: "shared"
          mountPath: "/var/log/app"
    - name: "collector"
      image: "alpine:3.21"
      command:
        - "sh"
        - "-c"
        - "sleep 3600"
      volumeMounts:
        - name: "shared"
          mountPath: "/logs"
  volumes:
    - name: "shared"
      emptyDir: {}
' > 'workload.yaml'
kubectl delete pod cobalt-295
kubectl apply -f workload.yaml

Containers in a Pod share a network namespace, but files are shared only through a shared volume mounted in both containers.

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