upgrade&rollback

04-work-with-helm-charts/03-upgrade-&-rollback-helm-chart.md

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+## Upgrade & Rollback a Helm Chart
+
+## Search Helm Repo for nginxdemo
+
+   -  **[Review nginxdemo chart in Github Repo](https://github.com/lerndevops/helm-charts/tree/main/packages)**
+   -  **nginxdemo has 4 chart versions (0.1, 0.2, 0.3, 0.4)**
+   -  **[we can also review on Artifacthub.io](https://artifacthub.io/packages/helm/sample-helm-charts/nginxdemo)**
+
+
+```t
+# Search Helm Repo
+
+    helm repo add lerndevops https://lerndevops.github.io/helm-charts/
+    helm search repo lerndevops/nginxdemo
+
+    Note: Should display latest version of nginxdemo from lerndevops helm repo
+
+# Search Helm Repo with --versions
+
+    helm search repo nginxdemo --versions
+    Note: Should display all versions of nginxdemo
+
+# Search Helm Repo with --version
+
+    helm search repo nginxdemo --version "CHART-VERSIONS"
+    helm search repo nginxdemo --version "0.2"
+    Note: Should display specified version of helm chart 
+```
+
+## Install specific version of Helm Chart
+
+```t
+# Install Helm Chart by specifying Chart Version
+    helm install nginxdemo lerndevops/nginxdemo --version "CHART-VERSION"
+    helm install nginxdemo lerndevops/nginxdemo --version "0.1"
+
+# List Helm Release
+    helm list 
+
+# List Kubernetes Resources Deployed as part of this Helm Release
+    helm status nginxdemo --show-resources
+    kubectl get deployment -o wide 
+    kubectl get services -o wide
+
+# Access Application
+    http://localhost:31232
+```
+
+## Helm Upgrade using Chart Version
+
+```t
+# Helm Upgrade using Chart Version
+    helm upgrade nginxdemo lerndevops/nginxdemo --version "0.2"
+
+# List Helm Release
+    helm list 
+
+# List Kubernetes Resources Deployed as part of this Helm Release
+    helm status nginxdemo --show-resources
+    kubectl get deployment -o wide
+
+# Access Application
+    http://localhost:31232
+
+# List Release History
+    helm history nginxdemo
+```
+
+## Helm Upgrade without Chart Version
+
+```t
+# Helm Upgrade using Chart Version
+    helm upgrade nginxdemo lerndevops/nginxdemo
+
+# List Helm Release
+    helm list 
+
+# List Kubernetes Resources Deployed as part of this Helm Release
+    helm status nginxdemo --show-resources
+    kubectl get deployment -o wide 
+
+    Note: it deploys the latest release Chart Version 0.4 (Which is default or latest Chart version)
+
+# Access Application
+    http://localhost:31232
+
+
+# List Release History
+    helm history nginxdemo 
+```
+
+## Helm Rollback
+
+- **Roll back a release to a previous revision or a specific revision**
+
+```t
+# Rollback to previous version
+    helm rollback RELEASE-NAME 
+    helm rollback nginxdemo
+
+# List Helm Release
+    helm list 
+
+# List Kubernetes Resources Deployed as part of this Helm Release
+    helm status nginxdemo --show-resources
+    kubectl get deployment -o wide  
+
+    Note: we Should see V2 version of Application (Chart Version 0.2)
+
+# Access Application
+    http://localhost:31232
+
+# List Release History
+    helm history nginxdemo
+```
+
+## Helm Rollback to specific Revision
+
+- **Roll back a release to a previous revision or a specific revision**
+
+```t
+# Rollback to previous version
+    helm rollback RELEASE-NAME REVISION
+    helm rollback nginxdemo 1
+
+# List Helm Release
+    helm list 
+
+# List Kubernetes Resources Deployed as part of this Helm Release
+    helm status nginxdemo --show-resources
+    kubectl get deployment -o wide
+
+    Note: we Should see V1 version of Application (Chart Version 0.1)
+
+# Access Application
+    http://localhost:31232
+
+
+# List Release History
+    helm history nginxdemo
+```
+
+## Summary 
+#### what we learned 
+- additional flags for `helm search repo` command
+- Install and Upgrade Helm Releases using Chart Versions
+- few commands as below 
+   - helm install
+   - helm search repo
+   - helm status
+   - helm upgrade
+   - helm rollback
+   - helm history