Attach VSCode to container from CLI

VSCode’s new “Remote development” features let you attach the editor to a remote system, for example, WSL, an SSH server, or a docker container.

The WSL integration lets you run code-insiders . from WSL, and it opens the current directory in a VSCode window automatically connected to WSL. However, it wasn’t obvious how to do the same for attaching to a docker container. After reading some of the code, I figured it out:

auth="attached-container+$(node -p 'Buffer.from(process.argv[1]).toString("hex")' "$containerId")"
code-insiders --remote="$auth" --folder-uri="vscode-remote://$auth/path/inside/container"

How it works:

As far as I can tell, VSCode lets you specify a --remote flag of the form <authority>+<target>

<authority> is one of dev-container, attached-container, or wsl. <target> depends on the type. For WSL, a target of default will attach to the default WSL distro. For attaching to a container, the target should be the hex-encoded container ID. We can compute this using a node one-liner.

Technically, it looks like the <target> can also be a JSON object converted to hex, where the JSON object contains multiple fields. I think this is used for the dev-container authority to specify both a local directory and a docker host.

To attach using a devcontainer configuration, the <authority> is dev-container and the <target> should be one of the following hex-encoded:

• path of the project on the host
• JSON of the form:

{hostPath: "/home/me/whatever", dockerHost:"I assume a docker host domain name and port goes here"}