Unclear documentation about sidecar containers

[parimaljanagithub]

restartPolicy under initContainers is not allowing to create Jobs specified into the below documents

Error Message:
Job in version "v1" cannot be handled as a Job: strict decoding error: unknown field "spec.template.spec.initContainers[0].restartPolicy"

Document Link:
https://kubernetes.io/docs/concepts/workloads/pods/init-containers/#pod-restart-reasons

[thisisharrsh]

Hi @parimaljanagithub, I believe the error message you are getting is because you might have used restartpolicy feild under the initcontainers section. But it is not allowed under the initcontainers.

/language en

[thisisharrsh]

Page related to the issue: https://kubernetes.io/docs/concepts/workloads/pods/init-containers/#pod-restart-reasons
/sig docs
/sig node

[parimaljanagithub]

Hi @thisisharrsh ,
Below is the Job configuration:

kind: Job
metadata:
  name: myjob
spec:
  template:
    spec:
      containers:
        - name: myjob
          image: alpine:latest
          command: ['sh', '-c', 'echo "logging" > /opt/logs.txt']
          volumeMounts:
            - name: data
              mountPath: /opt
      initContainers:
        - name: logshipper
          image: alpine:latest
          restartPolicy: Always
          command: ['sh', '-c', 'tail -F /opt/logs.txt']
          volumeMounts:
            - name: data
              mountPath: /opt
      restartPolicy: Never
      volumes:
        - name: data
          emptyDir: {}```

[thisisharrsh]

Could you please provide the code block with proper indentation?

[parimaljanagithub]

updated above section

[tamilselvan1102]

The indentation should be corrected as below

initContainers:
      - name: logshipper
        image: alpine:latest
        restartPolicy: Always
        command: ['sh', '-c', 'tail -F /opt/logs.txt']
        volumeMounts:
          - name: data
            mountPath: /opt
        restartPolicy: Never

[tamilselvan1102]

/kind bug

[sftim]

https://kubernetes.io/docs/concepts/workloads/pods/init-containers/#api-for-sidecar-containers mentions a feature gate, but doesn't make it explicitly clear that you need to enable it. The feature gate is named SidecarContainers.

The fix I recommend:

• add a brand new page https://kubernetes.io/docs/concepts/workloads/pods/sidecar-containers/
• edit https://kubernetes.io/docs/concepts/workloads/pods/init-containers/#api-for-sidecar-containers to direct readers to that new page

/remove-kind bug

I don't think there is anything actually incorrect.
/triage accepted
/retitle Unclear documentation about sidecar containers

[T-Lakshmi]

Is anybody working to fix this issue? If no, i can take it.

[tamilselvan1102]

/assign @T-Lakshmi

[justankiit]

Feel free to involve me, if you need any help.

[T-Lakshmi]

@kumarankit999 Sure, Thank you.

[T-Lakshmi]

PR raised to fix the issue #43346.

[sftim]

Also see #43610

[sftim]

To learn more, you can read (but not plagiarize) https://loft.sh/blog/kubernetes-init-containers/

[Sivakajan-tech]

Hi, I also having this problem I tried to add restartPolicy as Always to under containers and init containers, but I get the same error.

Error from server (BadRequest): error when creating "MakeChunks/hello.yaml": Deployment in version "v1" cannot be handled as a Deployment: strict decoding error: unknown field "spec.template.spec.containers[0].restartPolicy", unknown field "spec.template.spec.initContainers[0].restartPolicy"

apiVersion: apps/v1
kind: Deployment
metadata:
  name: bash
spec:
  selector:
    matchLabels:
      app: bash
  template:
    metadata:
      labels:
        app: bash
    spec:
      restartPolicy: Always  #1
      containers: # List of containers, not another list within spec
        - name: bash
          image: ubuntu:latest
          resources:
            limits:
              cpu: "700m"
              memory: "200Mi"
            requests:
              cpu: "700m"
              memory: "200Mi"
          resizePolicy:
            - resourceName: "cpu"
              restartPolicy: "NotRequired"
            - resourceName: "memory"
              restartPolicy: "RestartContainer"
          command: ["tail", "-f", "/dev/null"]
          restartPolicy: Always  #2
      initContainers: # Optional init containers, not nested in another list
        - name: init-1
          image: ubuntu:latest
          command:
            - sh
            - "-c"
            - "sleep 1s \n"
          restartPolicy: Always  #3

I do not got any errors for the # 1 restartPolicy, but #2 and #3 are gave the error mentioned at the top.

Im using Minikube, and my

 % kubectl version
WARNING: This version information is deprecated and will be replaced with the output from kubectl version --short.  Use --output=yaml|json to get the full version.
Client Version: version.Info{Major:"1", Minor:"27", GitVersion:"v1.27.3", GitCommit:"25b4e43193bcda6c7328a6d147b1fb73a33f1598", GitTreeState:"clean", BuildDate:"2023-06-14T09:47:38Z", GoVersion:"go1.20.5", Compiler:"gc", Platform:"darwin/arm64"}
Kustomize Version: v5.0.1
Server Version: version.Info{Major:"1", Minor:"27+", GitVersion:"v1.27.0-rc.0", GitCommit:"cf60ee25590ac79334f823b7f03cf33105a442c1", GitTreeState:"clean", BuildDate:"2023-03-23T18:59:06Z", GoVersion:"go1.20.2", Compiler:"gc", Platform:"linux/arm64"}

CC: @tamilselvan1102 @thisisharrsh @T-Lakshmi Your suggestions highly appriciatable

[stmcginnis]

Looks like you are using 1.27, but this feature was added in 1.28. https://kubernetes.io/blog/2023/08/25/native-sidecar-containers/

[Sivakajan-tech]

Thanks @stmcginnis. I updated my k8s

 % kubectl version
Client Version: v1.29.3
Kustomize Version: v5.0.4-0.20230601165947-6ce0bf390ce3
Server Version: v1.29.0

Even though I can not use Never and OnFailure in both places. (#1 and #3 I put this marker in the above comment). It says,

The Deployment "bash" is invalid: spec.template.spec.restartPolicy: Unsupported value: "Never": supported values: "Always"

The Deployment "bash" is invalid: spec.template.spec.initContainers[0].restartPolicy: Unsupported value: "Never": supported values: "Always"