Suddenly unable to attach and debug dotnet core application in docker container

[adamkarb]

I have an existing launch configuration that I have been using to successfully debug a dotnet core application within a Docker container. The configuration I use in launch.json is as follows:

{
    "name": "Docker .NET Core Attach",
    "type": "docker",
    "request": "attach",
    "platform": "netCore",
    "processId": "${command:pickRemoteProcess}",
    "sourceFileMap": {
        "/app": "${workspaceFolder}/repositories/myproject"
    }
}

What is happening as of late suddenly, is that when launching the debug process, the following occurs:

1. The dropdown asks me which containers I wish to attach. I select my dotnet core API container.
2. If vsdbg does not exist within the container, choose to install. Works fine.
3. Immediately afterwards, I get a vscode popup error No process with the specified id is currently running.

Before I began experiencing this bug/error, the "${command:pickRemoteProcess}" would provide me a dropdown of all processes running within the container I chose in step 1, but now it is not doing this, but immediately erroring.

What works:
If I start my dotnet core application in the container, enter the container and find the process ID within, and input it into the processId field of my launch configuration, it will successfully attach.

Are my configurations incorrect suddenly? Is there a better way to configure this setup?

[adamkarb]

Further context: I found the output from the OUTPUT pane of vscode for the remote-attach command. Not sure yet how to diagnose yet.

Executing: docker exec -i API "sh -s" < "/Users/adam/.vscode/extensions/ms-dotnettools.csharp-1.23.12/scripts/remoteProcessPickerScript"
OCI runtime exec failed: exec failed: container_linux.go:367: starting container process caused: exec: "sh -s": executable file not found in $PATH: unknown
Error Message: Command failed: docker exec -i API "sh -s" < "/Users/adam/.vscode/extensions/ms-dotnettools.csharp-1.23.12/scripts/remoteProcessPickerScript"

[karolz-ms]

@adamkarb could you add repro steps? E.g. does the problem reproduce with vanilla web API app created with dotnet new webapi --no-https?

Also, what is the OS, VS Code, and Docker extension version?

[adamkarb]

@karolz-ms System and versioning information:

Docker version 20.10.7, build f0df350

VS Code version: Code 1.56.2 (Universal) (054a9295330880ed74ceaedda236253b4f39a335, 2021-05-12T17:44:30.902Z)
OS version: Darwin x64 20.3.0

System Info

Item	Value
CPUs	Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz (16 x 2300)
GPU Status	2d_canvas: enabled gpu_compositing: enabled metal: disabled_off multiple_raster_threads: enabled_on oop_rasterization: enabled opengl: enabled_on rasterization: enabled skia_renderer: disabled_off_ok video_decode: enabled webgl: enabled webgl2: enabled
Load (avg)	2, 2, 2
Memory (System)	32.00GB (0.07GB free)
Process Argv	--crash-reporter-id 8641fbb2-0011-46a9-817d-eda5a1e01669
Screen Reader	no
VM	0%

Extensions (7)

Extension	Author (truncated)	Version
dotnet-test-explorer	for	0.7.5
auto-using	Fud	0.7.15
vscode-docker	ms-	1.13.0
csharp	ms-	1.23.12
mssql	ms-	1.10.1
remote-containers	ms-	0.177.2
vscodeintellicode	Vis	1.2.14

[adamkarb]

@karolz-ms I just tested with a plain web application in a docker container. I got the exact same results. The remoteProcessPickerScript is somehow not being picked up / executed as indicated by that log output above.

[karolz-ms]

Thanks, Adam. I can reproduce as well.

[karolz-ms]

OK I think I have figured it out. There was a relatively recent change to C# VS Code tools that changed the way process resolution works: dotnet/vscode-csharp#4509

In most cases you won't need to specify the process picker anymore; we default to looking for dotnet process so it should "just work". For reference, this configuration works for me with the plain web API:

{
    "name": "Docker .NET Core Attach",
    "type": "docker",
    "request": "attach",
    "platform": "netCore",
    "sourceFileMap": {
        "/src": "${workspaceFolder}"
    }
}

Please let us know if this gets you unblocked

[adamkarb]

@karolz-ms I am still suffering from this problem.

The error I get now looks like

Multiple processes were found matching the process name. Attach by process id instead.

There can be multiple dotnet processes running in the same container. Just in my example, for development, my entrypoint is a dotnet run <project> command which will take care of the compilation and execution. Because the pickRemoteProcess choice has been taken away from me, my only recourse without changing my development environment is to

1. Boot container.
2. Enter container and list processes to find out which process ID I need.
3. Go back to launch.json to hardcode it.

This is the return of ps aux in my container

root         1  0.0  0.6 3064072 80316 ?       SLsl 19:35   0:02 dotnet run ./myproject --no-launch-profile --configfile ./
root        48  0.1  0.0      0     0 ?        Z    19:35   0:04 [dotnet] <defunct>
root        65  0.0  0.0      0     0 ?        Z    19:35   0:02 [dotnet] <defunct>
root        85  0.0  0.0      0     0 ?        Z    19:35   0:01 [dotnet] <defunct>
root       160  0.0  0.0   4284   744 pts/0    Ss+  19:35   0:00 /bin/sh
root       175 10.2  0.0      0     0 ?        Z    19:35   6:45 [dotnet] <defunct>
root       395  1.6  5.7 19977160 710644 ?     SLl  19:36   1:04 dotnet exec /app/myproject/bin/container/Debug/netcoreapp2

Why has the ability to pick a remote process been removed completely? Can't a default be supported as well as a user choice?

[karolz-ms]

BTW opening the same issue in multiple repos like this microsoft/vscode#125878 is not going to get you a faster resolution, or win you any friends, frankly

[karolz-ms]

Looks like a problem with variable substitution in launch configurations. The following configuration should work:

{
    "name": "Docker .NET Core Attach",
    "type": "docker",
    "request": "attach",
    "platform": "netCore",
    "processId": "${command:pickRemoteProcess}"
},

but it does not (the process picker is never shown). Investigating...

[adamkarb]

BTW opening the same issue in multiple repos like this microsoft/vscode#125878 is not going to get you a faster resolution, or win you any friends, frankly

I opened that one first, before I realized this was the proper repository for the issue. I went ahead and closed it just for you.

[karolz-ms]

Thanks! I came to believe this is a regression in C# VS Code tooling and I have opened dotnet/vscode-csharp#4607 for the C# tooling owners to take a look

I also noticed the default .NET image does not contain ps executable, so I submitted a PR to switch to Ubuntu-based images as a workaround: #2996 Without ps the process picker will not be able to enumerate processes in the container.

[adamkarb]

@karolz-ms
Appreciate your diligence on this, will be following closely.

[karolz-ms]

The next OmniSharp release should have the fix for this debugging scenario--I do not think there is anything on the Docker extension side to change. Resolving as "external" for now, but please reopen/create new issue as necessary if something still does not work.