At DockerCon, a demo during a keynote shows Visual Studio Code capable of editing of Docker Compose files via an extension that will be available at the next update.

Docker Extension Pack If you’re using Visual Studio Code to work with Docker, whether to create Dockerfiles or Docker Compose YAML, or to write code that eventually goes into Docker containers ...

What you’ll need You can create a networked instance of Visual Studio Code on a Linux or macOS machine, or using a Docker image.