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

Question

My CI tool uses lifecycles so if Dev deployments works, it goes to QA.

I have an end to end test container that i want to run in kubernetes, but how do i get the exit code from the container?

Can i somehow run the container and get back the exit code in one command?

kubectl run -it doesn't seem to get the exit code and has some extra things to say after the container is done.

Answer 1

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: v1
kind: 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}"

Answer 2

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" deleted
pod default/exitcode terminated (Error)
$ echo $?
1

$ kubectl run -it --rm exitcode --image=nginx --restart=Never -- bash -c "exit 8"
pod "exitcode" deleted
pod default/exitcode terminated (Error)
$ echo $?
8

$ kubectl run -it --rm exitcode --image=nginx --restart=Never -- bash -c "exit 250"
pod "exitcode" deleted
pod default/exitcode terminated (Error)
$ echo $?
250

$ kubectl run -it --rm exitcode --image=nginx --restart=Never -- bash -c "exit 255"
pod "exitcode" deleted
pod 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 $a
pod "exitcode" deleted
pod 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" deleted
pod default/foobar terminated (Error)
rc=10

$ kubectl version
Client 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 wide
NAME         STATUS   ROLES    AGE    VERSION   INTERNAL-IP   EXTERNAL-IP   OS-IMAGE             KERNEL-VERSION      CONTAINER-RUNTIME
10.10.0.21   Ready    master   2d1h   v1.18.5   10.10.0.21    <none>        Ubuntu 16.04.6 LTS   4.4.0-184-generic   docker://18.9.7
10.10.0.22   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