How to start container with kubectl and get exit code back? without kubectl exec

To get the exit code from a Pod (container) you can get the pod details with the command:

kubectl get pod termination-demo --output=yaml

Output:

apiVersion: v1kind: Pod...    lastState:      terminated:        containerID: ...        exitCode: 0        finishedAt: ...        message: |          Sleep expired        ...

To know more, you can check the documentation.

To make it easier as you wish you can run:

kubectl get pod busybox-term -ojson | jq .status.containerStatuses[].lastState.terminated.exitCode

Or if you don't want to install jq, you can run:

kubectl get pod busybox-term --output="jsonpath={.status.containerStatuses[].lastState.terminated.exitCode}"

This way was mentioned by mWatney previously, so I've just put some additional details here:

This way you can return exit code 0-255 (after 255 it starts over, 256==0) from a Pod.

-it and --restart=Never are required, --rm is optional, but useful to remove failed pods.
--restart=Never tells the generator to create a Pod object instead of Deployment.

$ kubectl run -it --rm exitcode --image=nginx --restart=Never -- bash -c "exit 0"pod "exitcode" deleted$ echo $?0$ kubectl run -it --rm exitcode --image=nginx --restart=Never -- bash -c "exit 1"pod "exitcode" deletedpod default/exitcode terminated (Error)$ echo $?1$ kubectl run -it --rm exitcode --image=nginx --restart=Never -- bash -c "exit 8"pod "exitcode" deletedpod default/exitcode terminated (Error)$ echo $?8$ kubectl run -it --rm exitcode --image=nginx --restart=Never -- bash -c "exit 250"pod "exitcode" deletedpod default/exitcode terminated (Error)$ echo $?250$ kubectl run -it --rm exitcode --image=nginx --restart=Never -- bash -c "exit 255"pod "exitcode" deletedpod default/exitcode terminated (Error)$ echo $?255$ kubectl run -it --rm exitcode --image=nginx --restart=Never -- bash -c "exit 256"pod "exitcode" deleted$ echo $?0# exit code can also be assigned to a variable$ kubectl run -it --rm exitcode --image=nginx --restart=Never -- bash -c "exit 255" ; a=$? && echo $apod "exitcode" deletedpod default/exitcode terminated (Error)255

Update for LoganMzz:

$ kubectl run -it --rm --image=busybox --restart=Never foobar -- ash -c 'exit 10'; echo rc=$?pod "foobar" deletedpod default/foobar terminated (Error)rc=10$ kubectl versionClient Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.5", GitCommit:"e6503f8d8f769ace2f338794c914a96fc335df0f", GitTreeState:"clean", BuildDate:"2020-06-26T03:47:41Z", GoVersion:"go1.13.9", Compiler:"gc", Platform:"linux/amd64"}Server Version: version.Info{Major:"1", Minor:"18", GitVersion:"v1.18.5", GitCommit:"e6503f8d8f769ace2f338794c914a96fc335df0f", GitTreeState:"clean", BuildDate:"2020-06-26T03:39:24Z", GoVersion:"go1.13.9", Compiler:"gc", Platform:"linux/amd64"}$ kubectl get nodes -o wideNAME         STATUS   ROLES    AGE    VERSION   INTERNAL-IP   EXTERNAL-IP   OS-IMAGE             KERNEL-VERSION      CONTAINER-RUNTIME10.10.0.21   Ready    master   2d1h   v1.18.5   10.10.0.21    <none>        Ubuntu 16.04.6 LTS   4.4.0-184-generic   docker://18.9.710.10.0.22   Ready    <none>   2d1h   v1.18.5   10.10.0.22    <none>        Ubuntu 16.04.6 LTS   4.4.0-184-generic   docker://18.9.7

kubectl get po pod_name -ojson | jq .status.containerStatuses[].state.terminated.exitCode