Create, Update & Delete Deployment

This example program demonstrates the fundamental operations for managing on
Deployment resources, such as Create, List, Update and Delete.

You can adopt the source code from this example to write programs that manage
other types of resources through the Kubernetes API.

Running this example

Make sure you have a Kubernetes cluster and kubectl is configured:

kubectl get nodes

Compile this example on your workstation:

cd create-update-delete-deployment
go build -o ./app

Now, run this application on your workstation with your local kubeconfig file:

./app
# or specify a kubeconfig file with flag
./app -kubeconfig=$HOME/.kube/config

Running this command will execute the following operations on your cluster:

1. Create Deployment: This will create a 2 replica Deployment. Verify with
   kubectl get pods.
2. Update Deployment: This will update the Deployment resource created in
   previous step by setting the replica count to 1 and changing the container
   image to nginx:1.13. You are encouraged to inspect the retry loop that
   handles conflicts. Verify the new replica count and container image with
   kubectl describe deployment demo.
3. List Deployments: This will retrieve Deployments in the default
   namespace and print their names and replica counts.
4. Delete Deployment: This will delete the Deployment object and its
   dependent ReplicaSet resource. Verify with kubectl get deployments.

Each step is separated by an interactive prompt. You must hit the
Return key to proceed to the next step. You can use these prompts as
a break to take time to run kubectl and inspect the result of the operations
executed.

You should see an output like the following:

Creating deployment...
Created deployment "demo-deployment".
-> Press Return key to continue.

Updating deployment...
Updated deployment...
-> Press Return key to continue.

Listing deployments in namespace "default":
 * demo-deployment (1 replicas)
-> Press Return key to continue.

Deleting deployment...
Deleted deployment.

Cleanup

Successfully running this program will clean the created artifacts. If you
terminate the program without completing, you can clean up the created
deployment with:

kubectl delete deploy demo-deployment

Troubleshooting

If you are getting the following error, make sure Kubernetes version of your
cluster is v1.6 or above in kubectl version:

panic: the server could not find the requested resource