Advanced Kubernetes Deployment Exercise

Table of Contents

  1. Introduction

  2. Creating a Deployment

  3. Verifying Deployment

  4. Updating a Deployment

  5. Rolling Back a Deployment

  6. Pausing and Resuming a Deployment

  7. References

  8. Deployment Definition Files

1. Introduction

In this Kubernetes deployment exercise, let us learn to update deployments, event monitoring, and perform rollbacks.

2. Creating a Deployment

2.1 Using the Command Line

To create a deployment using the command line, run the following command:

kubectl create deployment my-deployment --image=nginx --replicas=3

2.2 Using a YAML Definition File

Alternatively, create the same deployment using the following YAML definition file (my-deployment.yaml):

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
        - name: my-container
          image: nginx:1.14.2
          ports:
            - containerPort: 80

Apply the deployment using:

kubectl apply -f my-deployment.yaml

3. Verifying Deployment

3.1 Deployment Details

Check the status of the deployment:

kubectl describe deployment my-deployment

Observe the number of replicas in the current and new ReplicaSets.

3.2 Scaling Events

Watch the events related to the deployment while updating the image:

kubectl get events --watch

You'll see events indicating the rolling update process.

4. Updating a Deployment

We'll explore three methods for updating deployments:

4.1 Using kubectl set image

We can use the kubectl set image command to update the image of the nginx deployment. For example, to update the nginx container image to version 1.23, run the following command:

kubectl set image deployment/nginx nginx=nginx:1.23

4.2 Using kubectl edit deployment

  1. Open the Deployment YAML File:

    • Use the following command to open the YAML configuration of the deployment in your default editor:

      kubectl edit deployment my-deployment

    • This command will open the deployment configuration for my-deployment.

  2. Make Changes:

    • Navigate to the spec.template.spec.containers section.

    • Update the image version or any other desired fields.

    • Save the file and exit the editor.

    • It automatically apply the changes to the configuration. You can watch the changes with the kubectl describe command.

4.3 Editing the YAML file

  1. Open the deployment YAML file for editing:

    vi my-deployment.yaml

  2. Make Changes:

    • Navigate to the spec.template.spec.containers section.

    • Update the image version.

    • Save the file and exit the editor.

    spec:
      containers:
        - name: my-container
          image: nginx:1.14.2  -->   change it to nginx:1.16.1
          ports:
            - containerPort: 80

  1. Apply the Changes:

    • The changes made in the YAML file will be applied to the deployment using the following command:

      kubectl apply -f my-deployment.yaml

5. Rolling Back a Deployment

5.1 Check Rollout History

View the rollout history of your deployment:

kubectl rollout history deployment/my-deployment

5.2 Roll Back to Previous Revision

To roll back to a previous revision:

kubectl rollout undo deployment/my-deployment

6. Pausing and Resuming a Deployment

Pause a deployment to apply fixes:

kubectl rollout pause deployment/my-deployment

Resume the rollout:

kubectl rollout resume deployment/my-deployment

7. References

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