ci: add changelogs to automated version updates

Add the links to the changelogs of the freshly updated components to the
automated PR that does the update. This allow verifying that we are not
missing any important changes before merging the update. This happened
recently with node-exporter 1.2 which changed some flag names that we
took 3 months to update.

Signed-off-by: Damien Grisonnet <dgrisonn@redhat.com>

scripts/get-new-changelogs.sh

@@ -0,0 +1,64 @@
+#!/bin/bash
+
+set -euo pipefail
+
+# Get the freshly updated components versions.
+# Should be only used after running ./scripts/generate-versions and before
+# committing any changes.
+get_updated_versions() {
+  # Get only the newly updated versions from the versions file.
+  echo "$(git diff -U0 -- "${VERSION_FILE}" | grep '^[+]' | grep -Ev '^(--- a/|\+\+\+ b/)' | tr -d '",:+' | awk -F'"' '{print $1}')"
+}
+
+# Returns github changelog url based on a given repository url and tag.
+get_changelog_url() {
+  echo "https://github.com/${1}/releases/tag/v${2}"
+}
+
+# Gets all the new changelogs from the updated components version.
+get_changelog_urls() {
+  while IFS= read -r updated_version; do
+    read -r component version <<< "${updated_version}"
+    case "${component}" in
+      alertmanager)
+        get_changelog_url "prometheus/alertmanager" "${version}"
+        ;;
+      blackboxExporter)
+        get_changelog_url "prometheus/blackbox_exporter" "${version}"
+        ;;
+      grafana)
+        get_changelog_url "grafana/grafana" "${version}"
+        ;;
+      kubeStateMetrics)
+        get_changelog_url "kubernetes/kube-state-metrics" "${version}"
+        ;;
+      nodeExporter)
+        get_changelog_url "prometheus/node_exporter" "${version}"
+        ;;
+      prometheus)
+        get_changelog_url "prometheus/prometheus" "${version}"
+        ;;
+      prometheusAdapter)
+        get_changelog_url "kubernetes-sigs/prometheus-adapter" "${version}"
+        ;;
+      prometheusOperator)
+        get_changelog_url "prometheus-operator/prometheus-operator" "${version}"
+        ;;
+      kubeRbacProxy)
+        get_changelog_url "brancz/kube-rbac-proxy" "${version}"
+        ;;
+      configmapReload)
+        get_changelog_url "jimmidyson/configmap-reload" "${version}"
+        ;;
+      *)
+        echo "Unknown component ${component} updated"
+        exit 1
+        ;;
+    esac
+  done <<< "$(get_updated_versions)"
+}
+
+# File is used to read current versions
+VERSION_FILE="$(pwd)/jsonnet/kube-prometheus/versions.json"
+
+get_changelog_urls