Support for Multiple Devcontainers

[kylejbrk]

I usually have multiple devcontainers per project. It would be a nice feature to have a prompt when multiple devcontainers are detected so the user can pick which devcontainer to attach their lsp to.

for example if I have the following in my project:

.devcontainer/
├── app1/
│   └── devcontainer.json
└── app2/
    └── devcontainer.json

I could maybe run a command and the plugin will prompt me which devcontainer to run my lsp in. this is basically the same as how vscode works with handling multiple devcontainers:
https://code.visualstudio.com/remote/advancedcontainers/connect-multiple-containers

[jedrzejboczar]

I haven't used this feature. I am not sure why would you need have multiple devcontainers per directory? Couldn't you just have one container with that has all the needed dependencies? But it may be that I am missing something.

It looks like this could be done using the --config flag, e.g. devcontainer read-configuration --workspace-folder . --config .devcontainer/app2/devcontainer.json. But this complicates the implementation as the current assumption was that there is one devcontainer per directory. So we would need to modify devcontainers.manager.ensure_up to search for devcontainer.json files and ask which to use (it's inside the coroutine so we can use vim.ui.select). But we always just use workspace_dir as the key for checking if devcontainer is running and for caching its configuration, so we would need to store also the information about which json file to use. I think we could have some cache table to store the mapping workspace_dir=>selected_config and then always use it to select the file to pass as --config X. This would then also be picked up by devcontainers.cli.exec so that we are able to start LSP server. It would be tricky to support changing this mapping after it has first been selected because we would need to restart lsp servers and clean up some state, but even VSCode doesn't support something like this in single instance, so it's probably safe to ignore for now.

I might not have time to work on this in the near future, but if someone is willing to submit PR you're welcome.

[kylejbrk]

@jedrzejboczar the use case is for mono repos. a better example is in the doc i linked showing the following project:

📁 project-root
    📁 .git
    📁 .devcontainer
      📁 python-container
        📄 devcontainer.json
      📁 node-container
        📄 devcontainer.json
    📁 python-src
        📄 hello.py
    📁 node-src
        📄 hello.js
    📄 docker-compose.yml

in this setup i can use my devcontainer to piggyback off the existing containers defined in docker compose. with a large project like this you cant just have everything run in a single container.

as far as implementation im not sure ill be much help. vscode handles this by prompting the user which devcontainer to run and attach to, and then spins up the devcontainer and installs vscode server where all the lsps will run container side. i assumed something like this could work with your project but im sure its not a simple ask. unfortunately i have yet to be able to recreate this workflow outside of vscode.