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Custom sandbox images let you prebake the repository, dependencies, compiled output, and test harness your agents need. Instead of spending minutes provisioning a workspace on every run, your agents start on the actual task immediately.

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Why Use a Custom Image

Custom images eliminate cold-start setup work (clone, install, transpile, and bootstrap) so agents spend their time on the actual task. They also reduce setup variance and lower sandbox memory requirements by keeping only what the agent needs.

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Build Your Own Custom Image

The OpenHands agent-server sandbox guide provides full documentation on building custom sandbox images. The approach is the same for the Enterprise Replicated VM deployment.

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Basic Pattern

  1. Start from the OpenHands agent-server base image.
  2. Keep the normal OpenHands entrypoint intact: extend the image, do not replace the entrypoint.
  3. Add your repo, docs, tools, and verification wrappers.
  4. Pre-run the expensive setup you do not want to repeat at task time.
  5. Publish the image to a registry and point the Replicated installer at it.
Do not override the entrypoint or replace the runtime contract of the base image. The installer expects standard OpenHands agent-server behavior. Only extend, do not replace.

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Base Image

Pin a specific version tag to ensure reproducible builds. Check ghcr.io/openhands/agent-server for the latest available tags.

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Version Compatibility

Each OpenHands Enterprise release expects a specific agent-server version. The base image tag you build from must match the release you run: the openhands-sdk inside the sandbox and the one inside the OpenHands application must agree on major and minor version. To find the expected tag, enable Use a Custom Sandbox Image in the Admin Console. The Sandbox Image Tag field defaults to the tag the current release expects. When a conversation starts on a custom image, OpenHands checks the sandbox’s agent-server version. If it does not match the release, the conversation fails with an error naming the expected and actual versions. Rebuild your image from the expected tag and update the Sandbox Image Tag field to fix it.
Rebuild your custom image before each upgrade. The agent-server base image changes with every OHE release, and an image built for an older release will be rejected by the version check.

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Example: Build and Push

Use --platform linux/amd64 because the Enterprise Replicated VM runs on x86-64.

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What to Bake In

Good candidates for prebaking:
  • Pinned repository checkouts
  • Package manager caches and installed dependencies (node_modules, Python virtualenvs, etc.)
  • Compiled or transpiled output
  • Native system packages (xvfb, libkrb5-dev, pkg-config, etc.)
  • Browser or Electron artifacts
  • Stable helper scripts such as prepare-* and *-verify wrappers

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What to Keep Out

Do not bake the following into your image:
  • Secrets, API keys, or personal credentials
  • Machine-specific paths or environment assumptions
  • Uncommitted source changes or task-specific fixes
  • Rapidly changing dependencies (use a lightweight prepare-* helper instead)
If the repository or dependencies change frequently, include a prepare-* script in the image so the agent can refresh only the parts that need updating without a full rebuild.

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Configure the Replicated VM Installer

Once your image is built and pushed to a registry, point the Replicated Admin Console at it.
  1. Open the Admin Console at https://admin.<your-base-domain>:30000.
  2. Navigate to Config and find the Sandbox Image section.
  3. Set the following fields:
  1. Click Save config and then Deploy to apply the change.
This setting applies to the sandbox / agent-server image only (the image that runs inside each agent’s isolated workspace). It does not replace the other OpenHands service images.

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Reference