There are several ways of how to get inside the Kubernetes container in a Pod.

• kubectl exec (reference link) creates additional process in the Pod's namespace and connects your console to it's stdin/stdout.

Examples:

kubectl exec 123456-7890 date
kubectl exec 123456-7890 -c ruby-container date
kubectl exec 123456-7890 -c ruby-container -i -t -- bash -il
kubectl exec 123456-7890 -i -t -- ls -t /usr

• kubectl attach (reference link) connects your console to stdin/stdout existing container process.

Example:

kubectl attach 123456-7890
kubectl attach 123456-7890 -c ruby-container
kubectl attach 123456-7890 -c ruby-container -i -t
kubectl attach rs/nginx

You can also connect to stdout/stderr of pod container(s) using kubectl logs command.

Examples:

kubectl logs nginx
kubectl logs nginx --all-containers=true
kubectl logs -lapp=nginx --all-containers=true
kubectl logs -p -c ruby web-1
kubectl logs -f -c ruby web-1

These answers on StackOverflow give you more information related to your question:

• kubectl exec into contain of multi container pod
• Execute bash command in pod with kubectl?
• Kubectl attach vs kubectl exec?
• How do you debug python code with kubernetes and skaffold?