Creating Kubernetes pods with your favorite OS to test new features

UPDATE 05/15/2020

I have since learned about Weave's footloose project, which provides a VM-like experience, but utilizes containers under the covers. Amazing project!

Original Post

As I dig deeper into Kubernetes it's been useful to spin up a pod with one of my favorite Operating Systems and review the configuration for that pod. This is super easy to do with kubectl run's --image option. To create an Ubuntu VM you can pass the ubuntu image name to "--image"

$ kubectl run -it --rm --image=unbuntu ubuntu -- bash

To create a CentOS pod you can use the centos image:

$ kubectl run -it --rm --image=centos centos -- bash

To create a Fedora pod you can use the fedora image:

$ kubectl run -it --rm --image=fedora fedora -- bash

And to create an alpine pod you can use the alpine image:

$ kubectl run -it --rm --image=alpine alpine -- ash

If you want to run a specific version of an OS you can add the version to the image name:

$ kubectl run -it --rm --image=fedora:26 fedora26 -- bash

Once the POD is up you can start reviewing the various Kubernetes objects that were created to support the pod. You can also use the "--dry-run" and output options to view the object that is created and sent to the API server:

$ kubectl run --image=alpine alpine --dry-run -o yaml

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    run: alpine
  name: alpine
spec:
  replicas: 1
  selector:
    matchLabels:
      run: alpine
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        run: alpine
    spec:
      containers:
      - image: alpine
        name: alpine
        resources: {}
status: {}

The YAML above can be copied to a file, modified and re-deployed with the kubectl create command. This is a fantastic way to tinker with all of the Kubernetes deployment options.