Creating a custom environment for agents

As an alternative to using GitHub Actions or cloud sandboxes managed by GitHub, you can provide a custom environment for GitHub Copilot sessions. A custom environment is a Linux machine or codespace running the Copilot host, copilotd.

You create the host and register it with your GitHub account. You can then select it as an environment in a client that supports custom environments. Registration makes an existing host available to clients.

You need a Copilot license and access to custom environments. You are responsible for the machine, its workspace and tools, and keeping the host running and up to date. Closing a client connection does not stop the host or the machine.

Using a Linux machine

Use Copilot CLI to run and register the host on a Linux machine.

1. Prepare the host

You need a Linux machine and npm or Homebrew to install the prerelease version of Copilot CLI. For installation requirements and other installation methods, see GitHub Copilot CLI 설치.

On the machine you want to use, prepare the workspace and install the tools and dependencies that your agent sessions need.
Install the prerelease version of Copilot CLI with npm:
```
npm install -g @github/copilot@prerelease
```
Alternatively, install it with Homebrew:
```
brew install copilot-cli@prerelease
```

2. Register the host

The host registers as an environment owned by the account you authenticate with.

Sign in to GitHub.com and follow the authentication prompts:
```
copilot login
```
Start Copilot CLI so that your account settings and feature flags load, then exit the interactive session:
```
copilot
```
Start the environment host. Replace HOST-NAME with a name that you will recognize in the environment selector.
```
copilot --environment-host "HOST-NAME"
```
The command starts the host and registers the machine under the name you chose. Keep the host running so that clients can connect to it.

3. Choose the environment

Connect from a client that supports selecting registered environments.

Sign in to the client with the same GitHub account you used to register the host.
Open Environments and select the host by the name you registered.

The client connects to the running host, where your agent sessions execute.

Using GitHub Codespaces

Use a development container feature to start and register the host automatically when your codespace starts. You need access to GitHub Codespaces. To use the commands below, you also need an authenticated installation of GitHub CLI.

1. Configure the codespace

The development container configuration determines how the host is installed.

In your repository, create or edit .devcontainer/devcontainer.json to add the host feature. For example:

{
  "image": "mcr.microsoft.com/devcontainers/base:ubuntu",
  "features": {
    "ghcr.io/github/copilot-host/copilotd:0": {}
  }
}

Optionally, configure the feature for your environment. Use :prerelease instead of :0 for the prerelease channel. To clone additional repositories, add a repositories option inside the feature's configuration object:
```
"ghcr.io/github/copilot-host/copilotd:0": {
  "repositories": "OWNER/REPOSITORY-1,OWNER/REPOSITORY-2"
}
```
Replace OWNER/REPOSITORY-1 and OWNER/REPOSITORY-2 with the owners and names of the repositories to clone.

2. Start and register the host

The feature starts copilotd and registers the codespace automatically when the container starts.

To create a new codespace, commit and push your development container configuration. Then create a codespace on that branch. Replace OWNER/REPOSITORY with the repository owner and name, and BRANCH with the branch containing your configuration.
```
gh codespace create -r OWNER/REPOSITORY -b BRANCH
```
For an existing codespace, rebuild its container instead. Replace CODESPACE-NAME with the name of your codespace.
```
gh codespace rebuild -c CODESPACE-NAME
```
Wait for the container to start and the host to register.

3. Choose the codespace environment

Use a client that supports selecting registered environments. The token used to sign in to the client must include the codespace scope.

Sign in to the client with the GitHub account that owns the codespace.
Open Environments and select the codespace.

If the codespace is stopped, connecting wakes it and starts copilotd automatically.

To inspect the host logs, run the following command in the codespace:

tail -F /workspaces/.copilotd/logs/copilotd.log