'Finding the name of a new pod with kubectl
I am new to k8s and I am running into a little problem here.
Here's the context:
I need to invoke kubectl delete [podname] via a crontask once a day, and wait until k8s recreates the pod, then log into the container in that pod and run a shell command.
So I query the deployment and get something like this:
user@host:~$ kubectl get pods
NAME READY STATUS RESTARTS AGE
firstpod-123456789-something 1/1 Running 570 2d
secondpod-http-backend-something 1/1 Running 597 2d
then I wrote a bash script that would delete the pods in a 5 minutes interval. That's the easy part.
Suppose I invoke kubectl delete firstpod-123456789-something and wait for k8s to recreate a new pod. That new pod would have a new name like firstpod-[some random hash here]-something
The problem is that I need to capture the name of that pod in my bash script so then I can exec a command in that pod like uname -a or whatever as to verify that the new pod is up and running just fine.
I googled it and read the kubectl docs but I don't think there's an easy way to do this via a bash script? I am assuming that the only way to get the pod name here would be via the k8s API?
I am happy to use any solution at this point. I wonder if there's any way that I rename the new pod when k8s spawns up a new one? so I could grep for a specific keyword?
Note that I don't want to egrep something like firstpod-[0-9]-something because that's just an example. A lot of pods have a lot of different names, that was just an example.
Thanks!
Solution 1:[1]
You need to label your deployment somehow, for example we set label app: myapp below:
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: nginx
spec:
template:
metadata:
labels:
app: my-app
spec:
containers:
- image: nginx
name: nginx
After that you can get deployment's pod name very easy:
POD=$(kubectl get pod -l app=my-app -o jsonpath="{.items[0].metadata.name}")
and execute some command there, for example:
kubectl exec -ti $POD -- uname -a
Solution 2:[2]
Like Nickolay wrote, use a label to help selecting. Then you can use
kubectl get pods -l app=my-app -o custom-columns=:metadata.name
This gets you the name of the pod that has the label "app=my-app"
Solution 3:[3]
Complementing what @nickgryg said, if kubernetes is in the cloud you can add the namespace and kubeconfig to get the pod name:
kubectl get pods -l app=my-app -o jsonpath="{.items[0].metadata.name}" -n my-namespace --kubeconfig=/home/$USER/.kube/kubeconfig
And to delete it with a single command, you can use the following:
NAMESPACE=my-namespace APP_NAME=my-app && kubectl delete -n $NAMESPACE pod $(kubectl get pods -l app=$APP_NAME -o jsonpath="{.items[0].metadata.name}" -n $NAMESPACE --kubeconfig=/home/$USER/.kube/kubeconfig) --kubeconfig=/home/$USER/.kube/kubeconfig
Solution 4:[4]
All other answers doesnt work for me
Not working option
kubectl -n $NAMESPACE get pods -l app.kubernetes.io/name=nats -o name
working option
kubectl -n $NAMESPACE get pods --selector=app.kubernetes.io/name=nats -o name
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow
| Solution | Source |
|---|---|
| Solution 1 | nickgryg |
| Solution 2 | P.Stromberg |
| Solution 3 | RexRod |
| Solution 4 | ImranRazaKhan |