kubernetes - Create multiple pods from the same YAML definition file

Question

So, I have a pod definition file and I was wondering if there was a way to use the kubectl apply command to create multiple instances of the pod from the same definition file. I know this can be done with a deployment but wondering if there was a way to quickly spin up multiple pods using the apply command?

question from:https://stackoverflow.com/questions/65672005/create-multiple-pods-from-the-same-yaml-definition-file

Answer 1

I know this can be done with a deployment but wondering if there was a way to quickly spin up multiple pods using the apply command?

Yes, this is possible but not with the simple kubectl apply command as it doesn't have such options/capabilities and cannot be used to create multiple instances of a pod from a single yaml definition file.

If you just need to create n number of independent pods, not managed by any replicaset, deployment, statefulset etc., you can use for this purpose a simple bash one-liner.

Suppose we want to quickly spin up 10 independent pods based on the following yaml template, named pod-template.yaml:

apiVersion: v1
kind: Pod
metadata:
  name: {{pod-name}}
spec:
  containers:
    - name: web
      image: nginx
      ports:
        - name: web
          containerPort: 80
          protocol: TCP

We can do it with the following script:

for i in {1..10}; do sed "s/{{pod-name}}/pod-$i/g" pod-template.yaml | kubectl apply -f - ; done

It will create 10 pods named pod-1, pod-2 ... pod-10:

$ for i in {1..10}; do sed "s/{{pod-name}}/pod-$i/g" pod-template.yaml | kubectl apply -f - ; done
pod/pod-1 created
pod/pod-2 created
pod/pod-3 created
pod/pod-4 created
pod/pod-5 created
pod/pod-6 created
pod/pod-7 created
pod/pod-8 created
pod/pod-9 created
pod/pod-10 created

And just in case you want to delete them now and don't want to do it one by one ;)

for i in {1..10};do kubectl delete pod pod-$i; done