Going back to using a script, because Woodpecker CI requires $$ escaping, which is annoying.

pipeline.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+
+# https://vaneyckt.io/posts/safer_bash_scripts_with_set_euxo_pipefail/
+# Not using "-x" because we aren't debugging.
+set -Eeuo pipefail
+
+# We get unbound var err if we don't set arg
+arg="${1:-}"
+
+echo "${registry_password}" | helm registry login -u "${registry_user}" --password-stdin "${registry_host}"
+helm lint "${chart_dir}"
+chart_version=$(grep '^version: ' "${chart_dir}/Chart.yaml" | cut -d' ' -f 2)
+helm package "${chart_dir}"
+
+# If chart already exists in the chart repository, don't push.
+if helm pull "oci://${registry_host}/${registry_path}/${chart_name}" --version "${chart_version}" &> /dev/null; then
+  echo -e "\e[31mWARNING: Chart ${chart_name} version ${chart_version} already exists in the repository.\nThis means that the chart's code has not changed, or you forgot to update the version in Chart.yaml.\e[0m"
+else
+  if [[ $arg == 'push' ]]; then
+    helm push "${chart_name}-${chart_version}.tgz" "oci://${registry_host}/${registry_path}"
+  fi
+fi