Add documentations for the release process of Helm charts (ray-projec…

…t#723)

Formalize and document the Helm release process.

Co-authored-by: Dmitri Gekhtman <[email protected]>
Signed-off-by: Kai-Hsun Chen <[email protected]>

docs/release/helm-chart.md

@@ -0,0 +1,49 @@
+# Helm charts release 
+
+We host all Helm charts on [kuberay-helm](https://github.com/ray-project/kuberay-helm). This document describes the process for release managers to release Helm charts.
+
+## The end-to-end workflow
+### Step 1: Update version in Chart.yaml
+Please update the value of `version` in [ray-cluster/Chart.yaml](https://github.com/ray-project/kuberay/blob/master/helm-chart/ray-cluster/Chart.yaml), [kuberay-operator/Chart.yaml](https://github.com/ray-project/kuberay/blob/master/helm-chart/kuberay-operator/Chart.yaml), and [kuberay-apiserver/Chart.yaml](https://github.com/ray-project/kuberay/blob/master/helm-chart/kuberay-apiserver/Chart.yaml) to the new release version (e.g. 0.4.0).
+
+### Step 2: Copy the helm-chart directory from kuberay to kuberay-helm
+In [kuberay-helm CI](https://github.com/ray-project/kuberay-helm/blob/main/.github/workflows/chart-release.yaml), `helm/chart-releaser-action` will create releases for all charts in the directory `helm-chart` and update `index.yaml` in the [gh-pages](https://github.com/ray-project/kuberay-helm/tree/gh-pages) branch when the PR is merged into `main`. Note that `index.yaml` is necessary when you run the command `helm repo add`. I recommend removing the `helm-chart` directory in the kuberay-helm repository and creating a new one by copying from the kuberay repository.
+
+### Step 3: Check the correctness
+When the PR is merged into `main`, the releases and `index.yaml` will be generated. You can check the correctness by:
+
+* Check whether the [releases](https://github.com/ray-project/kuberay-helm/releases) are created as expectation.
+* Check whether [index.yaml](https://github.com/ray-project/kuberay-helm/blob/gh-pages/index.yaml) exists or not.
+* Check whether [index.yaml](https://github.com/ray-project/kuberay-helm/blob/gh-pages/index.yaml) has metadata of all releases, including old versions.
+* Check the creation/update time of all releases and `index.yaml` to ensure they are updated.
+
+* Install charts from Helm repository.
+    ```sh
+    helm repo add kuberay https://ray-project.github.io/kuberay-helm/
+
+    # List all charts
+    helm search repo kuberay
+
+    # Install charts
+    helm install kuberay-operator kuberay/kuberay-operator
+    helm install kuberay-apiserver kuberay/kuberay-apiserver
+    helm install ray-cluster kuberay/ray-cluster   
+    ```
+
+## Delete the existing releases
+`helm/chart-releaser-action` does not encourage users to delete existing releases; thus, `index.yaml` will not be updated automatically after the deletion. If you really need to do that, please read this section carefully before you do that.
+
+* Delete the [releases](https://github.com/ray-project/kuberay-helm/releases)
+* Remove the related tags by the following command. If tags are not properly removed, [ray-project/kuberay/#561](https://github.com/ray-project/kuberay/issues/561) may occur.
+
+    ```sh
+    # git remote -v
+    # upstream        [email protected]:ray-project/kuberay-helm.git (fetch)
+    # upstream        [email protected]:ray-project/kuberay-helm.git (push)
+
+    # The following command deletes the tag "ray-cluster-0.4.0".
+    git push --delete upstream ray-cluster-0.4.0
+    ```
+* Remove `index.yaml`
+* Trigger kuberay-helm CI again to create new releases and new index.yaml.
+* Follow "Step3: Check the correctness" to test it.