envbuilder don't recognize "dockerComposeFile" param

[BoBRoID]

Hi! My devcontainer.json looks like this:

{
  "name": "keycrm",
  "dockerComposeFile": [
    "../example.docker-compose.yml"
  ],
  "service": "app",
  "services": ["app", "db"],
  "forwardPorts": [80],
  "postAttachCommand": "service apache2 start",
  "extensions": [
    "felixfbecker.php-pack",
    "cweijan.vscode-mysql-client2"
  ]
}

and coder don't recognize "dockerComposeFile" option. It's described in devcontainer.json schema, and supported by my IDE (phpstorm) as well. But when I'm trying to create a workspace with such devcontainer it usually fallback to default image.
So, maybee in future, would envbuilder support docker-compose files to build, or I'm using it in wrong way? I'm trying to make developer's workspace with standalone environment, but creating only "app" is not enough in case of no DB.

[dannykopping]

@BoBRoID thank you for reporting this; we're keen on adding compose support.
We'll need to do some experimentation first, and I've added a new ticket #135 to track that.