ChartMuseum — Open-Source Helm Chart Repository Server

Introduction

ChartMuseum is a self-hosted HTTP server for Helm charts maintained under the Helm project umbrella. It provides a simple way to host a private Helm chart repository with pluggable storage backends including S3, GCS, Azure Blob, and local filesystem. It implements the Helm chart repository specification and adds a REST API for chart management.

What ChartMuseum Does

• Serves Helm chart packages over HTTP with automatic index.yaml generation
• Accepts chart uploads via a REST API for CI/CD integration
• Supports cloud storage backends: Amazon S3, Google Cloud Storage, Azure Blob, and more
• Provides basic authentication and bearer token authorization
• Tracks chart versions and allows overwriting or immutable version policies

Architecture Overview

ChartMuseum is a single Go binary that runs an HTTP server. On startup, it scans the configured storage backend for .tgz chart packages and builds an in-memory index. The index is served at /index.yaml per the Helm spec. Uploads via /api/charts are validated, stored in the backend, and reflected in the index. A cache layer reduces storage read latency for frequently accessed index entries.

Self-Hosting & Configuration

• Run as a standalone binary, Docker container, or deploy via the official Helm chart
• Configure the storage backend via environment variables or CLI flags
• Set --storage=amazon with AWS_ACCESS_KEY_ID and bucket name for S3 hosting
• Enable basic auth with --basic-auth-user and --basic-auth-pass flags
• Use --allow-overwrite to permit re-uploading the same chart version

Key Features

• Multiple storage backends: local filesystem, S3, GCS, Azure Blob, Alibaba OSS, OpenStack
• Automatic index.yaml generation and rebuild on chart upload or deletion
• REST API for uploading, listing, and deleting charts from CI/CD pipelines
• Configurable chart immutability to prevent overwriting published versions
• Lightweight single binary that runs anywhere without external dependencies

Comparison with Similar Tools

• Harbor — Full container and chart registry with RBAC, scanning, and replication
• Nexus Repository — Universal artifact manager, heavier but supports more formats
• OCI registries — Helm 3+ supports OCI-based chart storage, no separate server needed
• GitHub Pages — Free static hosting for public chart repos, no upload API
• JFrog Artifactory — Enterprise artifact management with Helm support, commercial

FAQ

Q: Does ChartMuseum support OCI-based Helm charts? A: No. ChartMuseum implements the classic Helm chart repository protocol. For OCI distribution, use an OCI registry like Harbor or GHCR.

Q: Can I use ChartMuseum with Helm 3? A: Yes. ChartMuseum works with both Helm 2 and Helm 3. Add it as a repo with helm repo add.

Q: How do I integrate ChartMuseum into CI/CD? A: Use curl or the helm-push plugin to upload packaged charts to the /api/charts endpoint after a successful build.

Q: Is there a web UI for browsing charts? A: ChartMuseum itself is API-only. Community tools like Kubeapps or Monocular provide a web UI on top.

Sources

• https://github.com/helm/chartmuseum
• https://chartmuseum.com/