Why can I not attach a shell to Google's hello-app:v1 container?

wwillfred

1/5/24, 2:02 AM

I've deployed a simple Kubernetes bare pod (hello-world-pod) in a cluster with nodes running Ubuntu 18.04 in Vagrant. When I run this command,

kubectl exec -it hello-world-pod -- /bin/sh

...I get the error:

error: Internal error occurred: error executing command in container: failed to exec in container: failed to start exec "0cc4cd8766f1e809ede55707dd422ffa4509804beb2006200b05ff4197f9a63c": OCI runtime exec failed: exec failed: unable to start container process: exec: "/bin/sh": stat /bin/sh: no such file or directory: unknown

Why can I not attach a shell to the container in this pod? I am able to successfully attach a shell to the ubuntu container and the nginx container, but not this one.

Here is the manifest for the problematic pod:

apiVersion: v1
kind: Pod
metadata:
  name: hello-world-pod
spec:
  containers:
  - name: hello-world
    image: gcr.io/google-samples/hello-app:1.0
    ports:
    - containerPort: 80

BTW I'm using containerd, not docker, as my runtime environment.

Thanks in advance!

265

2 + 0

container

vagrant

kubernetes

Score:0

Ubuntu

dummyuser

1/5/24, 6:17 AM

Welcome, this sample container is a pretty small container with 26.8 MB. A shell is not needed, so the maintainer did not install a shell. See Error message /bin/sh: no such file or directory

Container should be kept as small as possible, things that are not needed should not be installed. The runtime environment does not matter.

+ 2

wwillfred

1/5/24, 3:34 PM

That makes sense, but in the Pluralsight course [Managing the Kubernetes API Server and Pods](https://www.pluralsight.com/courses/managing-kubernetes-api-server-pods), the instructor attaches a shell to this container and in a different example executes the `/usr/bin/killall` command on this container. Did this container use to have a shell and other commands that are no longer there in the current version?

dummyuser

1/5/24, 3:51 PM

I cannot comment in content of Pluralsight as I do not know details of the training. Even `/usr/bin/killall` is not installed in this container, but I never needed a `/usr/bin/killall` inside a container.

Score:0

Ubuntu

Maccaman

1/24/24, 8:29 AM

Apparently the shell is gone in the later revisions.

Try using an older version of the image for the Pluralsight demo, e.g. gcr.io/google-samples/hello-app@sha256:2b0febe1b9bd01739999853380b1a939e8102fd0dc5e2ff1fc6892c4557d52b9

It even has killall.

+ 0

Elon Musk

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EN: Why can I not attach a shell to Google's hello-app:v1 container?

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