Daniel Helfand
3 years ago
2 changed files with 40 additions and 12 deletions
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# Blue Green |
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The blue green strategy is not supported by built-in Kubernetes Deployment but available via third-party Kubernetes controller. |
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This example demonstrates how to implement blue-green deployment via [Argo Rollouts](https://github.com/argoproj/argo-rollouts): |
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The [blue green strategy](https://argoproj.github.io/argo-rollouts/concepts/#blue-green) is not supported by Kubernetes Deployments, |
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but it is available via [Argo Rollouts](https://github.com/argoproj/argo-rollouts). This example demonstrates how to implement a blue-green |
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deployment using Argo CD and Argo Rollouts together. |
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1. Install Argo Rollouts controller: https://github.com/argoproj/argo-rollouts#installation |
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2. Create a sample application and sync it. |
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## Prerequisites: |
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1. Install Argo CD: https://argo-cd.readthedocs.io/en/stable/operator-manual/installation/#core |
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2. Install Argo Rollouts: https://argoproj.github.io/argo-rollouts/installation/ |
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3. Install the kubectl rollouts plugin: https://argoproj.github.io/argo-rollouts/installation/#kubectl-plugin-installation |
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## Walkthrough |
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1. Let's start by creating an Argo CD Application and sync it with the helm chart in this git repository: |
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``` |
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argocd app create blue-green --repo https://github.com/argoproj/argocd-example-apps --dest-server https://kubernetes.default.svc --dest-namespace default --path blue-green && argocd app sync blue-green |
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``` |
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Once the application is synced, you can access it using `blue-green-helm-guestbook` service: |
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``` |
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argocd app create --name blue-green --repo https://github.com/argoproj/argocd-example-apps --dest-server https://kubernetes.default.svc --dest-namespace default --path blue-green && argocd app sync blue-green |
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kubectl port-forward svc/blue-green-helm-guestbook 8080:80 -n default |
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``` |
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Once the application is synced you can access it using `blue-green-helm-guestbook` service. |
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After running the command above, the application can be viewed at localhost:8080. |
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3. Change image version parameter to trigger blue-green deployment process: |
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2. Change the image version parameter to trigger the blue-green deployment process: |
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``` |
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argocd app set blue-green -p image.tag=0.2 && argocd app sync blue-green |
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``` |
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Now application runs `ks-guestbook-demo:0.1` and `ks-guestbook-demo:0.2` images simultaneously. |
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The `ks-guestbook-demo:0.2` is still considered `blue` available only via preview service `blue-green-helm-guestbook-preview`. |
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After running the command above, the Application runs `ks-guestbook-demo:0.1` and `ks-guestbook-demo:0.2` images simultaneously. |
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The `ks-guestbook-demo:0.2` is still considered blue or only available via the preview service `blue-green-helm-guestbook-preview`. |
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4. Promote `ks-guestbook-demo:0.2` to `green` by patching `Rollout` resource: |
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You can run the following to view the blue preview service: |
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``` |
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argocd app patch-resource blue-green --kind Rollout --resource-name blue-green-helm-guestbook --patch '{ "status": { "verifyingPreview": false } }' --patch-type 'application/merge-patch+json' |
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kubectl port-forward svc/blue-green-helm-guestbook-preview 8081:80 -n default |
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``` |
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This promotes `ks-guestbook-demo:0.2` to `green` status and `Rollout` deletes old replica which runs `ks-guestbook-demo:0.1`. |
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The blue preview version of the application will be available at localhost:8081, but the active version of the application at localhost:8080 |
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is still displaying the older version of the application. |
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3. Promote `ks-guestbook-demo:0.2` to `green` by patching `Rollout` resource: |
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``` |
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kubectl argo rollouts promote blue-green-helm-guestbook -n default |
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``` |
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This promotes `ks-guestbook-demo:0.2` to `green` status and the `Rollout` deletes the old replica which runs `ks-guestbook-demo:0.1`. |
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If you stop and rerun `kubectl port-forward svc/blue-green-helm-guestbook 8080:80 -n default` again, you should see the new |
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version is now available via the active service at localhost:8080. |
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