Cannot attach to extension host in container

[chrmarti]

Issue Type: Bug

That is a local extension host running the container while VS Code is connected to the container with Remote-Containers.

I see this with Debug: Attach to Node Process and the preview version of that.

VS Code version: Code - Insiders 1.45.0-insider (d4b8ec9, 2020-05-05T07:13:27.726Z)
OS version: Darwin x64 19.2.0
Remote OS version: Linux x64 4.19.76-linuxkit

System Info

Item	Value
CPUs	Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHz (16 x 2400)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled metal: disabled_off multiple_raster_threads: enabled_on oop_rasterization: disabled_off protected_video_decode: unavailable_off rasterization: enabled skia_renderer: disabled_off_ok video_decode: enabled viz_display_compositor: enabled_on viz_hit_test_surface_layer: disabled_off_ok webgl: enabled webgl2: enabled
Load (avg)	3, 2, 2
Memory (System)	32.00GB (0.36GB free)
Process Argv	-psn_0_1974754
Screen Reader	no
VM	22%

Item	Value
Remote	Container vscode-remote-containers_devc…
OS	Linux x64 4.19.76-linuxkit
CPUs	Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHz (4 x 2400)
Memory (System)	7.78GB (1.77GB free)
VM	0%

Extensions (13)

Extension	Author (truncated)	Version
tsl-problem-matcher	eam	0.1.1
vscode-docker	ms-	1.1.0
remote-containers	ms-	0.115.99
remote-ssh-edit-nightly	ms-	2020.4.9540
remote-ssh-nightly	ms-	2020.4.9540
remote-wsl	ms-	0.44.2
debugger-for-chrome	msj	4.12.6
vscode-eslint	dba	2.1.5
vscode-pull-request-github	Git	0.16.0
vscode-docker	ms-	1.1.0
python	ms-	2020.4.76186
vscode-versionlens	pfl	0.26.1
vscode-open-in-github	sys	1.13.1

[weinand]

@chrmarti what do you mean by "preview version of that"?
Of what?

[chrmarti]

@weinand I have Debug: Attach to Node Process and Debug: Attach to Node Process (preview) in the command palette.

[weinand]

Aha, now I understand...

[connor4312]

Thanks for the issue. Inside the bootloader called when programs are launched, we spawn a separate "watchdog" process that we use to set up communication since "wait for inspector" action that we run in the debugee is synchronous and blocks the main thread. We did the same thing for processes we attached to (not just those we launch) since the machinery was already built for that.

Therefore, we required Node to spawn the process to attach to any program. However, when js-debug itself is doing the attachment, it can run the necessary logic in the extension host process directly and we can avoid spawning a separate process.

[chrmarti]

Verified when starting the target with a fixed port:

/bin/code-insiders --extensionDevelopmentPath=`pwd` --inspect-extensions 1234

The preview version doesn't show the process and the non-preview version fails to attach when starting without fixed port:

/bin/code-insiders --extensionDevelopmentPath=`pwd`

The non-preview version appears to use 0 as the port:

Not sure if this is a known limitation, but the non-preview version should at least not try to connect to port 0. Extracting a new issue for that.