add rebuild script for index.yaml
this is necessary until https://github.com/helm/chart-releaser/issues/133
diff --git a/scripts/README.md b/scripts/README.md
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--- /dev/null
+++ b/scripts/README.md
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+# Rebuilding Index
+
+The Helm `index.yaml` is hosted on the `gh-pages` branch of this repo. If this
+index becomes out-of-sync with the releases, you can rebuild it by using a
+GitHub Actions Workflow.
+
+## Prerequisites
+
+- To use the `rebuild.sh` script with our workflow, the `rebuild.sh`
+ script must be checked in to the `gh-pages` branch. If you make any changes
+ to the script in this directory, make sure you also commit the same changes
+ to the `gh-pages` branch.
+- You must have permission to run GitHub Actions Workflows for this repo.
+
+## Running the Action
+
+- Navigate to the GitHub Actions UI.
+- Use the `Run Workflow` button to run the workflow.
+- Review the Pull Request created by the workflow.
+- When approved, merge the Pull Request into the `gh-pages` branch.
diff --git a/scripts/rebuild.sh b/scripts/rebuild.sh
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+++ b/scripts/rebuild.sh
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+#!/usr/bin/env bash
+
+# Run this script from the root of the helm repo, e.g.,
+# ./scripts/rebuild.sh. You must have curl and cr installed. See
+# https://github.com/helm/chart-releaser#installation.
+
+# Set this to a valid URL *without* an index.yaml if you want to regenerate
+# a new index.html. If you want to append to an existing one, you can
+# use a real address like `https://apache.github.io/couchdb-helm`. If an existing
+# index.yaml is found at this URL, then any packages we generate will
+# be appended, which can result in duplicates.
+HELM_REPO=${HELM_REPO:-https://apache.github.io}
+
+# Create a temporary directory and clean it up when we're done.
+TMP_DIR=$(mktemp -d)
+function cleanup()
+{
+ echo "Removing temporary directory ${TMP_DIR}."
+ rm -rf $TMP_DIR
+}
+trap cleanup EXIT
+
+# Optional variables you can define in your env
+PACKAGE_DIR=${PACKAGE_DIR:-${TMP_DIR}}
+CHARTS_DIR=${CHARTS_DIR:-charts}
+INDEX=${INDEX:-index.yaml}
+GITHUB_OWNER=${GITHUB_OWNER:-apache}
+GITHUB_REPO=${GITHUB_REPO:-couchdb-helm}
+
+# Calculated variables
+DOWNLOADS_BASE="https://github.com/${GITHUB_OWNER}/${GITHUB_REPO}/releases/download"
+
+# List all tags oldest to newest, followed by the 'main' branch.
+tags="$(git tag -l --sort=creatordate) main"
+
+# Clean the packages release directory that `cr` uses.
+mkdir -p ${PACKAGE_DIR}
+rm -rf ${PACKAGE_DIR}/*
+
+# Download existing assets from Github
+for tag in $tags; do
+ dl_url="${DOWNLOADS_BASE}/${tag}/${tag}.tgz"
+ cd ${PACKAGE_DIR}
+ curl -LOs --fail ${dl_url}
+ result=$?
+ if [[ ${result} -eq 0 ]]; then
+ echo "Downloaded $dl_url".
+ else
+ echo "Could not download $dl_url".
+ fi
+ cd -
+done
+
+echo "Writing index to ${INDEX}"
+rm ${INDEX}
+cr index --owner ${GITHUB_OWNER} --git-repo ${GITHUB_REPO} --charts-repo ${HELM_REPO} -p ${PACKAGE_DIR} -i ${INDEX}
