pod.yml
apiVersion: v1
kind: Pod
metadata:
name: hello-pod
labels:
zone: prod
version: v1
spec:
containers:
- name: hello-ctr
image: hello-world:latest
ports:
- containerPort: 8080kubectl create -f pod.yml
kubectl get pods
NAME READY STATUS RESTARTS AGE
hello-pod 0/1 CrashLoopBackOff 5 5mWhy CrashLoopBackOff?
The hello-world is actually exiting meaning Kubernetes thinks its crashing, and keeps restarting and exiting and going in CrashLoppBackOff. When you docker run your hello-world container you get this:
$ sudo docker run hello-world
Hello from Docker!
This message shows that your installation appears to be working correctly.
To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
(amd64)
3. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
4. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal.
To try something more ambitious, you can run an Ubuntu container with:
$ docker run -it ubuntu bash
Share images, automate workflows, and more with a free Docker ID:
https://hub.docker.com/
For more examples and ideas, visit:
https://docs.docker.com/get-started/
$
So, it's a one-time thing and not a service. Kubernetes has Jobs or CronJobs for these types of workloads.
In this case the expected behavior is correct. The hello-world container is meant to print some messages and then exit after completion. So this is why you are getting CrashLoopBackOff -
Kubernetes runs a pod - the container inside runs the expected commands and then exits.
Suddenly there is nothing running underneath - so the pod is ran again -> same thing happens and the number of restarts grows.
You can see that inkubectl describe pod where Terminated state is visible and the Reason for it is status Completed. If you would choose a container image which does not exit after completion the pod would be in running state.