I am trying to use a Docker (Envbuilder) workspace in Coder for development in a dev container and for the most part it is working as expected. I can create the workspace, checkout a git repository with my dev container definition in it and it will build the container and allow me to use both VSCode desktop and code-server in the browser to develop inside the container.

My issue (or probably more of a minor inconvenience than an actual issue) is that both VSCode desktop and code-server start in the /workspaces/ folder instead of the /workspaces/[project name] folder and the VSCode extensions defined in the devcontainer.json do not get installed.

If I checkout my git repo in Windows and allow VSCode desktop to run the devcontainer in WSL2, everything works as expected: it starts in the /workspaces/[project name] folder and the extensions get installed correctly. So it seems that I have configured the devcontainer.json correctly, at least for VSCode desktop. Does Coder require a slightly different configuration? It what I am trying to do possible? I have included my devcontainer definition below:

devcontainer.json:

{
    "build": {
        "dockerfile": "Dockerfile"
    },  
    "customizations": {
    "vscode": {
        "extensions": ["ms-vscode.cpptools-extension-pack"]
    }
    }
}

Dockerfile:

FROM debian:13.0-slim

RUN apt-get update && apt-get install --no-install-recommends -y \
    ca-certificates \
    build-essential \
    cmake \
    curl \
    gdb \
    git \
    && rm -rf /var/lib/apt/lists/*

I'd appreciate someone taking a look to see if they can spot what I'm doing wrong.