posit/workbench-session-init repository overview

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⁠Posit Workbench Session Init container image

This container image is an init container for Workbench. It stages the Workbench session runtime components under /opt/session-components for use by another container. Use this image to share components with a session container through a Kubernetes volume, or to copy them into a custom session image at build time.

⁠Quick reference

⁠Related images

For Kubernetes deployments, Workbench uses these images together. See the repository README⁠ for Helm configuration.

⁠How to use this image

⁠With the Workbench Helm chart

The Workbench Helm chart⁠ by default configures Workbench to use a workbench-session-init image to bootstrap a workbench-session image. Configure the images as shown below.

session:
  image:
    repository: "ghcr.io/posit-dev/workbench-session"
    tag: "latest"

components:
  sessionInit:
    image:
      repository: "ghcr.io/posit-dev/workbench-session-init"

See the repository README⁠ for a full chart example.

⁠Image tags

Posit publishes images to:

• Docker Hub: docker.io/posit/workbench-session-init
• GitHub Container Registry: ghcr.io/posit-dev/workbench-session-init

Ubuntu 24.04 is the only OS.

Tag formats where YYYY.MM.P is any supported Workbench version:

• YYYY.MM.P - Default OS
• YYYY.MM.P-ubuntu-24.04 - Explicit OS
• latest - Latest version, default OS

⁠Architectures

Posit publishes workbench-session-init images for linux/amd64 only. linux/arm64 builds remain in developer preview until Workbench supports ARM in production.

⁠Environment variables

The init container does not consume any environment variables at runtime.

⁠Volumes

The init container stages the Workbench session components at /opt/session-components in the image. Mount a shared volume at the same path to expose them to a session container.

The session container mounts the same volume at /opt/session-components to consume the runtime components at the path Workbench expects.

⁠User

The container starts as root so the session container can read the session components from the shared volume.

⁠Examples

⁠Building a custom session image

You can pull the session components into a custom session image at build time using a multi-stage build:

FROM ghcr.io/posit-dev/workbench-session-init:2026.09.0 AS session-init

FROM your-custom-base
COPY --from=session-init /opt/session-components /opt/session-components

The resulting image bundles the session components directly, so it can run Workbench sessions without an init container at runtime.

See the session-init extending example⁠ for a complete example of this pattern.

⁠Migrating from legacy image

This image replaces the legacy rstudio/workbench-session-init⁠ image. The runtime contents are unchanged. The image still ships the Workbench session components at /opt/session-components for a session container to consume. The differences are in how the image is published.

⁠Image references

Posit published the legacy image as rstudio/workbench-session-init on Docker Hub and ghcr.io/rstudio/workbench-session-init on GHCR, tagged by OS (jammy, ubuntu2204, jammy-<version>, ubuntu2204-<version>) for linux/amd64 only. Update your image reference to one of the new locations and pick a tag that pins to your desired Workbench version. See Image tags⁠ and Architectures⁠.

⁠Base OS options

The legacy image shipped Ubuntu 22.04 only. This image ships Ubuntu 24.04 only. See Image tags⁠.

⁠What did not change

• Source path for the session runtime components (/opt/session-components)
• Compatibility with the Workbench server and session containers

⁠Caveats

⁠Security

Review these images before using them in production. Organizations with specific Common Vulnerabilities and Exposures (CVE) or vulnerability requirements can rebuild these images to meet their security standards.

Posit rebuilds these images weekly for Posit product editions under active support, pulling in operating system patches.

⁠Version compatibility

The workbench-session-init image version must match the Workbench server version. Mismatched versions can cause session startup failures or unexpected behavior.