BUG: Predefined variables only partially work in `mounts` section

[ontoneio]

In the mounts property documentation it reads:

Defaults to unset. Cross-orchestrator way to add additional mounts to a container. Each value is a string that accepts the same values as the Docker CLI --mount flag. Environment and pre-defined variables may be referenced in the value. For example: "mounts": [{ "source": "dind-var-lib-docker", "target": "/var/lib/docker", "type": "volume" }]

When trying to use pre-defined variables in the mount property array like so:

"mounts": [
    "source=${localEnv:HOME}/.bashrc,target=${containerEnv:HOME}/.bashrc,type=bind"
  ],

Seems like the ${localEnv:HOME} variable is working but not the containerEnv. I am met with this error:

[2023-07-27T21:29:17.441Z] Start: Run: docker run --sig-proxy=false -a STDOUT -a STDERR  --mount source=/home/vscode/.bashrc,target=${containerEnv:HOME}/.bashrc,type=bind --mount type=volume,src=vscode,dst=/vscode --mount type=bind,src=/mnt/wslg/runtime-dir/wayland-0,dst=/tmp/vscode-wayland-f5cf98e1-b777-482d-a8b0-901e9ce6936c.sock -l devcontainer.local_folder=\\wsl.localhost\Ubuntu\home\vscode\projects\web-cms -l devcontainer.config_file=/home/vscode/projects/web-cms/.devcontainer/devcontainer.json -e GITHUB_ACTIONS= -e GLOBAL_DEPS=/workspaces/node_modules/.bin -e WSLENV=VSCODE_CLI_REMOTE_ENV/w:ELECTRON_RUN_AS_NODE/w:WT_SESSION:VSCODE_BIN/p:GIT_CRED_MGR/p:DOCKER_LOCAL_BIN:WT_PROFILE_ID --init --privileged --privileged --entrypoint /bin/sh vsc-web-cms-91be336f19f43f7d6233276339f0cc37087480b85a7d91e2890c5b9dfef4ecdb-uid -c echo Container started
[2023-07-27T21:29:17.515Z] docker: Error response from daemon: invalid mount config for type "bind": invalid mount path: '${containerEnv:HOME}/.bashrc' mount path must be absolute.
See 'docker run --help'.

So it seems like you cannot actually use pre-defined variables with in the mount property. Unless I am missing something in the docs.

Thanks

[avidal]

If you take a look at the pre-defined variables table it calls out that containerEnv is only usable as an expansion source in the remoteEnv option...although the table header leaves a bit to be desired (just says "Type").

I'm not sure why that's the case exactly (I don't work on the reference CLI, which is what informed the spec)

[filip-komarzyniec]

@avidal what you suggest (if I get the idea correctly) does not work either. Having this .devcontainer file:

"remoteEnv": {
  "HOME": "/home/vscode"
},
"workspaceMount": "source=${localWorkspaceFolder}/,target=${containerEnv:HOME},type=bind,consistency=cached",

I still get the following error:

[2023-12-10T19:25:05.698Z] Start: Run: /opt/homebrew/bin/podman run --sig-proxy=false -a STDOUT -a STDERR --mount source=/Users/filip.komarzyniec/my_folder/,target=${containerEnv:HOME},type=bind,consistency=cached --mount type=volume,src=vscode,dst=/vscode -l devcontainer.local_folder=/Users/filip.komarzyniec/my_folder -l devcontainer.config_file=/Users/filip.komarzyniec/my_folder/.devcontainer/devcontainer.json --userns=keep-id --entrypoint /bin/sh vsc-my-folder-ff86802263add83c79a982bce4a09566e6d62985ede81565f4faed5769c5352a -c echo Container started
[2023-12-10T19:25:05.837Z] Error: invalid container path "${containerEnv:HOME}", must be an absolute path

Is there any progress on the issue or any decisions on it whatsoever?

[stewartadam]

Just bumped against this (exact same use case, too) in microsoft/vscode-remote-release#10003. Mounting volumes into the container user's home directory is useful for tools persisting configuration there.