Custom environments (advanced)

The Domino Standard Environment includes Copilot, Claude Code, and Codex out of the box. You can build a custom Compute Environment if your team needs to standardize on a different coding agent, pin specific versions, or add additional CLI tools.

Note
 The DSE can be used without coding assistants. If your organization prefers a standard environment without pre-installed coding assistants, use the domino-standard-environment-no-assistants image. The full image URL for the current release is available in the Domino Compute Environment Catalog. Note that the image URL changes with each release, so always refer to the catalog for the latest version.

When to use a custom environment

  • Your organization uses a coding assistant not included in the standard environment, for instance, Cody, Cursor-based agents, Continue, or Aider.

  • You need to lock agent versions for compliance or reproducibility.

  • You want to pre-configure API keys or authentication tokens so users don’t need to authenticate manually.

  • You need to bundle additional CLI tools, MCP servers, or plugins alongside your coding agent.

Install a VS Code extension

To add a VS Code extension to your environment, install it directly from the marketplace using code-server in your Dockerfile.

# Example: Install the Continue extension for VS Code
RUN code-server --install-extension Continue.continue
Tip
 Extensions install to the user’s home directory automatically. With home directory persistence enabled, extensions installed at runtime will also survive workspace restarts.

Install a CLI-based agent

CLI-based coding agents work in any workspace IDE. Install them via pip, npm, or shell in your Dockerfile.

OpenCode is a terminal-native coding agent with a built-in TUI, multi-model support, and MCP integration.

# Install OpenCode CLI
RUN curl -fsSL https://opencode.ai/install | bash

Authentication

Most coding agents require an API key or authentication token. In Domino workspaces, each user authenticates their coding agent interactively when they launch it the first time.

Credentials stored in the user’s home directory persist across workspace restarts when home directory persistence is enabled.

Important
 Domino does not currently provide a secure mechanism to inject secrets via environment variables at the environment level. Do not hardcode API keys in your Dockerfile. Users should authenticate interactively on first use, or use their own API key files stored in their persistent home directory.

For agents that support file-based configuration, users can create a config file in their home directory once, and it will be reused across workspace restarts:

# Example: Claude Code reads ~/.claude/config.json automatically
# Users create this file once in their persistent home directory
mkdir -p ~/.claude
cat > ~/.claude/config.json << 'EOF'
{
  "apiKey": "sk-ant-...",
  "model": "claude-sonnet-4-20250514"
}
EOF

Persist agent configuration across restarts

Workspace home directory persistence automatically saves files under /home/ubuntu/. Most coding agents store their config and history in the home directory, so they survive restarts by default.

If your agent stores configuration outside the home directory, create symlinks in your Dockerfile or startup script:

# Symlink agent config to home directory for persistence
RUN mkdir -p /home/ubuntu/.config/my-agent && \
    ln -sf /home/ubuntu/.config/my-agent /etc/my-agent/config

Add MCP servers

If your coding agent supports Model Context Protocol (MCP) servers, bundle custom MCP servers in your environment to extend agent capabilities:

# Install a custom MCP server
RUN pip install my-custom-mcp-server

# Configure Claude Code to use the MCP server
RUN mkdir -p /home/ubuntu/.claude && \
    cat > /home/ubuntu/.claude/mcp_servers.json << 'EOF'
{
  "my-server": {
    "command": "python",
    "args": ["-m", "my_custom_mcp_server"],
    "env": {}
  }
}
EOF

Full example: Custom environment Dockerfile instructions

To set this up, create a new environment using a base environment that has VS Code support, such as the Domino Standard Environment, then add the following to the Dockerfile Instructions field:

USER root

# Install Aider CLI
RUN pip install aider-chat

# Install a VS Code extension from the marketplace
RUN code-server --install-extension Continue.continue

USER ubuntu
Note
 After you’ve build your custom environment, select the environment when you launch a workspace. All coding agents and tools configured in the environment work right away.

Next steps

  • Troubleshoot: Get information about known issues and workarounds for coding assistants in Domino workspaces.