Kubernetes how to make Deployment to update image - kubernetes

To update an image in a Kubernetes Deployment, we can use the kubectl set image command. This command helps us to easily choose the new image for our app. It changes the Deployment’s settings directly. Then, it starts a rolling update of the app without any downtime. By using this way, we make sure the new image gets deployed well and our running app stays stable.

In this article, we will look at different ways to update images in Kubernetes Deployments. We will talk about using the kubectl set image command. We will also discuss the rolling update strategy, automating with CI/CD, manual changes to Deployment settings, and tips for image updates. Here is a short overview of what we will learn:

  • How to use kubectl set image to update Deployment in Kubernetes
  • The rolling update strategy for Kubernetes Deployment image updates
  • Automating image updates in Kubernetes Deployments with CI/CD
  • Manually changing a Kubernetes Deployment to update the image
  • Tips for updating images in Kubernetes Deployments
  • Common questions about Kubernetes image updates

For more details, you can read related articles like What are Kubernetes Deployments and how do I use them? and How do I perform rolling updates in Kubernetes?.

How to use kubectl set image to update Deployment in Kubernetes?

To update a Kubernetes Deployment with a new image, we can use the kubectl set image command. This command helps us change the container image for the Deployment without editing YAML files by hand.

Syntax

kubectl set image deployment/<deployment-name> <container-name>=<image-name>:<tag>

Example

Imagine we have a Deployment called my-app with a container named my-container. If we want to update its image to my-image:latest, we write this command:

kubectl set image deployment/my-app my-container=my-image:latest

Additional Options

  • –record: This flag helps us keep track of changes in the resource’s notes. It is good for seeing changes in the Deployment history.

Here is an example with recording:

kubectl set image deployment/my-app my-container=my-image:latest --record

This command will update the Deployment and we can see the change in the history when we run kubectl rollout history deployment/my-app.

Verify the Update

To check how the Deployment is doing after the update, we can use:

kubectl rollout status deployment/my-app

This command gives us the status of the rollout. It tells us if the new image has been applied successfully.

Using kubectl set image, we can manage image updates in our Kubernetes Deployments. This way, we make sure our applications run the latest versions with little downtime. For more information on Deployments, check what are Kubernetes Deployments and how do I use them.

What is the rolling update strategy for Kubernetes Deployment image updates?

The rolling update strategy in Kubernetes helps us to update the images of our Deployments without downtime. This strategy slowly replaces old Pods with new ones. It keeps the number of Pods we want during the update.

Key Features of Rolling Update Strategy:

  • Incremental Updates: We update Pods one by one or in small groups. It depends on the settings we choose.
  • Health Checks: Kubernetes checks if the new Pods are healthy. If a new Pod does not work, Kubernetes can go back to the old version.
  • Configuration Parameters:
    • maxUnavailable: This tells us how many Pods can be unavailable during the update.
    • maxSurge: This tells us how many extra Pods can be created beyond the desired number during the update.

Example of a Rolling Update Configuration:

Here is an example of a Deployment configuration that uses rolling updates:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 3
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 1
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
      - name: my-app-container
        image: my-app:latest
        ports:
        - containerPort: 80

In this example: - The maxSurge: 1 allows us to create one extra Pod for a short time. - The maxUnavailable: 1 means we will have at least two Pods working during the update.

Command to Trigger Update:

To update the image in a Deployment, we can use this command:

kubectl set image deployment/my-app my-app-container=my-app:new-image

This command changes the image of the container we picked. Kubernetes will handle the rolling update using the strategy we set.

For more details on Kubernetes Deployment strategies, we can check this article.

How to automate image updates in Kubernetes Deployments with CI/CD?

We can automate image updates in Kubernetes Deployments. This helps our development process and reduces downtime. We can do this by using Continuous Integration (CI) and Continuous Deployment (CD) tools like Jenkins, GitHub Actions, or GitLab CI/CD. Here is a simple guide to set it up.

Step 1: Set Up CI/CD Pipeline

  1. Choose a CI/CD Tool: Pick a CI/CD tool that works for us. Some common tools are Jenkins, GitHub Actions, and GitLab CI/CD.

  2. Define Your Pipeline: Create a file for pipeline configuration. For example, use .gitlab-ci.yml for GitLab, Jenkinsfile for Jenkins, or .github/workflows/ci.yml for GitHub Actions.

Example: GitHub Actions

Here is an example of a GitHub Actions workflow that builds a Docker image and updates the Kubernetes deployment:

name: CI/CD Pipeline

on:
  push:
    branches:
      - main

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout code
        uses: actions/checkout@v2

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1

      - name: Log in to Docker Hub
        uses: docker/login-action@v1
        with:
          username: ${{ secrets.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_PASSWORD }}

      - name: Build and push Docker image
        uses: docker/build-push-action@v2
        with:
          context: .
          push: true
          tags: your-image-name:latest

      - name: Set up kubectl
        uses: azure/setup-kubectl@v1
        with:
          version: 'latest'

      - name: Deploy to Kubernetes
        run: |
          kubectl set image deployment/your-deployment your-container=your-image-name:latest --record
          kubectl rollout status deployment/your-deployment

Step 2: Update Kubernetes Deployment

We use the kubectl set image command to update the image of the existing deployment. The --record flag helps to track what we change in the deployment history.

Step 3: Trigger Deployments on Image Updates

We can set our CI/CD tool to trigger deployments automatically when a new image is built and pushed to the registry.

Best Practices

  • Version Tags: It is good to use version tags instead of latest. This helps us to roll back if needed.
  • Health Checks: We should add readiness and liveness probes in our deployments. This helps to reduce downtime when we update.
  • Monitor Deployments: Use tools like Prometheus and Grafana to watch our deployments and get alerts if there are failures.

For more information on setting up CI/CD pipelines in Kubernetes, we can refer to the article on how do I set up CI/CD pipelines for Kubernetes.

How to manually edit a Kubernetes Deployment to change the image?

To change the image of a Kubernetes Deployment, we can use the kubectl edit command. This command lets us change the Deployment resource directly in our cluster.

Here is the way to edit a Deployment:

kubectl edit deployment <deployment-name>

We need to replace <deployment-name> with the name of our Deployment.

When we run this command, it opens our default text editor. This is usually vi or nano. We will see the current setup of the Deployment. We need to find the spec.template.spec.containers section. This is where the container images are listed. It looks something like this:

spec:
  template:
    spec:
      containers:
      - name: <container-name>
        image: <current-image>:<tag>

Next, we change the image field to the new image we want to use:

        image: <new-image>:<new-tag>

After we make our changes, we save and close the editor. Kubernetes will automatically apply the new setup. This will start a rolling update of our Deployment with the new image.

We can check if the update was successful by looking at the status of the Deployment:

kubectl rollout status deployment/<deployment-name>

This command shows us the rollout status of the Deployment. It will tell us if the update worked.

For more information about managing Kubernetes Deployments, we can look at this article.

What are best practices for updating images in Kubernetes Deployments?

When we update images in Kubernetes Deployments, we can follow some best practices. These help to keep everything running well and reduce downtime. Here are some key strategies:

  1. Use Semantic Versioning: We should tag images with semantic versioning like myapp:v1.0.0 instead of using latest. This helps us see changes and go back if we need to.

  2. Implement Rolling Updates: We can use Kubernetes’ rolling update strategy. This means we replace old pods with new ones gradually. It reduces downtime and makes rollbacks easy. We can set up the Deployment like this:

    strategy:
  type: RollingUpdate
  rollingUpdate:
    maxUnavailable: 1
    maxSurge: 1

  3. Set Resource Limits: We need to define resource requests and limits for each container. This makes sure the new image does not use too many resources. This can help avoid problems:

    resources:
  requests:
    memory: "128Mi"
    cpu: "500m"
  limits:
    memory: "256Mi"
    cpu: "1"

  4. Health Checks: We should use readiness and liveness probes. This checks if the new pods are working well before we send traffic to them:

    readinessProbe:
  httpGet:
    path: /health
    port: 8080
  initialDelaySeconds: 5
  periodSeconds: 10

  5. Automate Image Updates: We can use CI/CD pipelines to automate building, testing, and deploying images. Tools like Jenkins or GitHub Actions help us with this.

  6. Use Canary Deployments: We can first deploy the new image to a small group of users. This lets us monitor and check the new version. We can do this with a different Deployment and service for the canary version.

  7. Monitor Deployments: We should use monitoring tools like Prometheus and Grafana. These tools help us watch the performance of new images after deployment. This way, we can find problems early.

  8. Use Annotations for Versioning: We can add annotations to our deployments with the image version. This helps us track changes:

    metadata:
  annotations:
    image.version: "v1.0.0"

  9. Rollback Procedures: We should know how to roll back if the new deployment does not work. We can use this command:

    kubectl rollout undo deployment/my-deployment

  10. Testing Before Production: We should test new images in a staging environment that is like production. This helps us find issues before we deploy.

By following these best practices, we can make updating images in Kubernetes Deployments more reliable and efficient. For more details on managing Kubernetes deployments, we can check out what are Kubernetes deployments and how do I use them.

Frequently Asked Questions

1. How do we update a Kubernetes Deployment image using the command line?

We can update a Kubernetes Deployment image using the kubectl set image command. For example, if our Deployment is called my-deployment, we can run this command:

kubectl set image deployment/my-deployment my-container=my-image:latest

This command will change the specified container in the Deployment to use the new image. For more steps, check our guide on how to use kubectl set image to update Deployment in Kubernetes.

2. What is the rolling update strategy in Kubernetes?

The rolling update strategy in Kubernetes helps us update our application without any downtime. It does this by slowly replacing the old Pods with new ones. This way, we can keep a certain number of Pods running during the update. For more details on rolling updates, read our article on how do I perform rolling updates in Kubernetes.

3. How can we automate image updates in Kubernetes Deployments?

We can automate image updates in Kubernetes by using CI/CD pipelines. Tools like Jenkins or GitHub Actions can start deployments automatically when we push a new image to our container registry. This makes it easier to keep our application updated. For more information on setting up CI/CD for Kubernetes, see our guide on how do I set up CI/CD pipelines for Kubernetes.

4. What are the best practices for updating images in Kubernetes?

The best practices for updating images in Kubernetes are tagging images with version numbers, using rolling updates to keep downtime low, and testing updates in a staging area before going to production. Also, we should use health checks to make sure new Pods work well before we remove the old ones. More about this is in our article on best practices for Kubernetes Deployments.

5. How can we manually edit a Kubernetes Deployment to change the image?

To manually change a Kubernetes Deployment, we can use the kubectl edit command. This opens the Deployment in our text editor. We find the image field under the containers section. Then we update it with the new image tag, save our changes, and exit the editor. This method changes the Live Kubernetes configuration. For more info on editing resources, check our article on how do I manage the lifecycle of a Kubernetes Pod.

By knowing and using these methods, we can make sure our deployments and updates for applications in Kubernetes go smooth and effective.