synapse

packaged by Chainguard

Chainguard Container for synapse

Matrix reference homeserver for federated real-time messaging

Chainguard Containers are regularly-updated, secure-by-default container images.

Download this Container Image

For those with access, this container image is available on cgr.dev:

docker pull cgr.dev/ORGANIZATION/synapse:latest

Be sure to replace the ORGANIZATION placeholder with the name used for your organization's private repository within the Chainguard Registry.

Compatibility Notes

This image is a drop-in replacement for the official ghcr.io/element-hq/synapse Docker image. Key differences include:

• Minimal base: Built on Wolfi instead of Debian, significantly reducing the CVE surface.
• Non-root by default: Runs as uid 991 (the synapse user), matching upstream conventions. The upstream image runs as root and uses gosu to drop privileges; this image runs as non-root directly.
• Minimal shell: The :latest tag includes BusyBox for Helm chart compatibility. Use the -dev variant for full debugging tools.
• jemalloc: Pre-configured via LD_PRELOAD environment variable. The upstream image auto-detects jemalloc at a Debian-specific path; this image sets it explicitly.
• Python venv: Synapse is installed in a virtual environment at /opt/synapse rather than the system Python path.

Getting Started

Synapse requires a configuration file before it can start. Use the generate command to create one:

docker run --rm \
  -v synapse-data:/data \
  -e SYNAPSE_SERVER_NAME=my.matrix.host \
  -e SYNAPSE_REPORT_STATS=no \
  cgr.dev/ORGANIZATION/synapse:latest generate

Then start the homeserver:

docker run -d \
  --name synapse \
  -v synapse-data:/data \
  -p 8008:8008 \
  cgr.dev/ORGANIZATION/synapse:latest

Verify the server is running:

curl http://localhost:8008/_matrix/client/versions

Configuration

Synapse is configured via the homeserver.yaml file in the /data directory. The start.py entrypoint reads standard Synapse environment variables (e.g., SYNAPSE_CONFIG_DIR, SYNAPSE_CONFIG_PATH, SYNAPSE_DATA_DIR, SYNAPSE_WORKER) with the same defaults as the upstream image.

For production deployments, it is strongly recommended to use PostgreSQL instead of the default SQLite database. See the Synapse documentation on database setup for details.

Helm Chart Installation

Synapse can be deployed on Kubernetes using the community matrix-synapse Helm chart:

helm repo add ananace-charts https://ananace.gitlab.io/charts
helm install synapse ananace-charts/matrix-synapse \
  --set image.repository=cgr.dev/ORGANIZATION/synapse \
  --set image.tag=latest

Refer to the chart documentation for the full list of configurable values.

Documentation and Resources

• Synapse GitHub Repository
• Synapse Administration Guide
• Matrix Protocol Specification
• Synapse Configuration Manual
• GitHub Container Registry: element-hq/synapse

What are Chainguard Containers?

Chainguard's free tier of Starter container images are built with Wolfi, our minimal Linux undistro.

All other Chainguard Containers are built with Chainguard OS, Chainguard's minimal Linux operating system designed to produce container images that meet the requirements of a more secure software supply chain.

The main features of Chainguard Containers include:

• Minimal design, without unnecessary software bloat
• Daily builds to ensure container images are up-to-date with available security patches
• High quality build-time SBOMs attesting to the provenance of all artifacts within the image
• Verifiable signatures provided by Sigstore
• Reproducible builds with Cosign and apko (read more about reproducibility)

For cases where you need container images with shells and package managers to build or debug, most Chainguard Containers come paired with a development, or -dev, variant.

In all other cases, including Chainguard Containers tagged as :latest or with a specific version number, the container images include only an open-source application and its runtime dependencies. These minimal container images typically do not contain a shell or package manager.

Although the -dev container image variants have similar security features as their more minimal versions, they include additional software that is typically not necessary in production environments. We recommend using multi-stage builds to copy artifacts from the -dev variant into a more minimal production image.

Need additional packages?

To improve security, Chainguard Containers include only essential dependencies. Need more packages? Chainguard customers can use Custom Assembly to add packages, either through the Console, chainctl, or API.

To use Custom Assembly in the Chainguard Console: navigate to the image you'd like to customize in your Organization's list of images, and click on the Customize image button at the top of the page.

Learn More

Refer to our Chainguard Containers documentation on Chainguard Academy. Chainguard also offers VMs and Libraries — contact us for access.

Trademarks

This software listing is packaged by Chainguard. The trademarks set forth in this offering are owned by their respective companies, and use of them does not imply any affiliation, sponsorship, or endorsement by such companies.