Create, Update & Delete Deployment
This example program demonstrates the fundamental operations for managing on
Deployment resources, such as
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:
- Create Deployment: This will create a 2 replica Deployment. Verify with
kubectl get pods.
- Update Deployment: This will update the Deployment resource created in
previous step by setting the replica count to 1 and changing the container
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.
- Rollback Deployment: This will rollback the Deployment to the last
revision. In this case, it's the revision that was created in Step 1.
kubectl describeto verify the container image is now
nginx:1.12. Also note that the Deployment's replica count is still 1; this is because a Deployment revision is created if and only if the Deployment's pod template (
.spec.template) is changed.
- List Deployments: This will retrieve Deployments in the
defaultnamespace and print their names and replica counts.
- 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
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. Rolling back deployment... Rolled back deployment... -> Press Return key to continue. Listing deployments in namespace "default": * demo-deployment (1 replicas) -> Press Return key to continue. Deleting deployment... Deleted deployment.
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
If you are getting the following error, make sure Kubernetes version of your
cluster is v1.6 or above in
panic: the server could not find the requested resource
Note: the example only works with the code within the same release/branch.