How to deploy and debug a program from a devcontainer on a remote system?

Question

How to deploy and debug a program from a devcontainer on a remote system?

J. Müller 0

My desired workflow would be to open my C++ project in VS22 on my Windows system, built the binary in a Linux based devcontainer and deploy it for remote-debugging to another system or VM. While the first part of it works without any issues, I ´m struggling to set up a working configuration for the remote debugging part. The according section in my launch.vs.json file currently looks like following (I removed the "deploy" instructions temporarily to get rid of another source of possible errors, just trying to start a gdb session with MyApp I copied there manually.):

{
  "name": "Debug MyApp on MyVM",
  "project": "CMakeLists.txt",
  "projectTarget": "MyApp",
  "type": "cppgdb",
  "disableDeploy": true,
  "debuggerConfiguration": "gdb",
  "MIMode": "gdb",
  "remoteMachineName": "-538176799;MyVM (username=root, port=22, authentication=Password)",
  "cwd": "/tmp",
  "program": "/tmp/MyApp",
  "setupCommands": [
    { "text": "-enable-pretty-printing","ignoreFailures": true }
  ]
}

When I select and launch this configuration as a startup item, the binary is built as intended inside the devcontainer, but after that I end up with an error popup with the message: Unable to find devcontainer.json.

In the Cross Platform Logging output I find:

17:12:36.8883565 [Info, Thread 1]	liblinux.RemoteSystemBase: Connecting over SSH to MyVM:22
17:12:37.1887015 [Info, Thread 47]	liblinux.Shell.CommonCommandBase: Command "cat C:\src\myapp/.devcontainer/devcontainer.json" finished with exit code 1 after 169,0114ms
17:12:37.1887015 [Info, Thread 47]	liblinux.IO.RemoteFileSystemImpl: Connecting over SFTP to MyVM:22

Looking at other liblinux.Shell log lines it seems to me these are executed inside the devcontainer and while the path to the devcontainer.json file is correct on my Windows system it looks of course differently when mounted inside the devcontainer.

So how do I need to change my configuration to get a remote debugging session started when I´m building my current target inside a devcontainer?

1 answer

Your answer

Answer 1

Surya Amrutha Vaishnavi Lanka (INFOSYS LIMITED) 1,115 Microsoft External Staff

Thanks for reaching out Based on your configuration, the error message you're facing ("Unable to find devcontainer.json") suggests that the debugger is looking for the devcontainer configuration file in the wrong path or context. Here are some steps you can take to address this issue:

Verify Path to devcontainer.json: Ensure that the path to the devcontainer.json file is correct inside the devcontainer. When you mount the project in the devcontainer, the file structure might differ from your local Windows setup.

Switch CWD (Current Working Directory): Modify the cwd property in your launch.vs.json to ensure it corresponds to the working directory inside the devcontainer where MyApp and devcontainer.json reside. For example, if the structure is like /home/user/project/myapp, set it like so
Check Remote Machine Name: The remoteMachineName format you're using is a bit unusual. Make sure it matches the expected format for SSH connections.

Environment Variables: Ensure any required environment variables that your app or the debugger expects are set in your devcontainer setup.

Deploy Instructions: Once you've set the correct path, consider adding back your deploy instructions in the configuration. This might help to ensure everything is properly synchronized when you initialize the debugging session.

Installation of Required Tools: Make sure you have gdb installed in your devcontainer, as well as any other dependencies that your application or the debugging setup might require.

J. Müller 0 Reputation points

2025-11-07T14:01:16.12+00:00
Many thanks for your recommendations.

Of course looks the path to the devcontainer.json different when mounted inside the devcontainer (Linux), than on the host (Windows). But I still don´t get how this should contribute to the issue as the relative path of a devcontainer file inside a project is standardized to be always ./.devcontainer/devcontainer.json and I also have no clue how I could change this standardized path by configuration? And finally I still don´t get why it even might be required to access the devontainer.json file from inside the running devcontainer, as all information in there should be irrelevant and inaccessible from this perspective (at least in the general case).

Documentation of cwd says: "Specifies the current directory on the remote machine to run "program" from. The directory must exist." so I would assume it should be the path on the target VM, not the one inside the devcontainer. Nevertheless I changed it according to your recommendation, but it did not yield any change.

The remoteMachineName was filled in by autocompletion from Visual Studios Connection Manager. They usually look like this in my setup and work well in this form for remote debugging setups not involving a devcontainer. I also tried the plain hostname, as well as the IP of my VM. Both did not resolve the issue.

I´m not aware my app or debugger require any special environment variables. Also the entire deployment process currently does not even reach a state where it would have access to any - possibly wrong or missing - env vars.

As recommended I added the deploy configuration again, choosing to do the deployment from host to VM, not from devcontainer to VM. So the config now looks like:

{ "name": "Debug MyApp on MyVM", "project": "CMakeLists.txt", "projectTarget": "MyApp", "type": "cppgdb", "disableDeploy": true, "debuggerConfiguration": "gdb", "MIMode": "gdb", "remoteMachineName": "-538176799;MyVM (username=root, port=22, authentication=Password)", "cwd": "/tmp", "program": "/tmp/MyApp", "setupCommands": [ { "text": "-enable-pretty-printing","ignoreFailures": true } ], "deploy": [{ "targetMachine": "-538176799;MyVM (username=root, port=22, authentication=Password)", "deploymentType": "LocalRemote", "sourcePath": "${projectDir}\\build\\linux64-debug\\MyApp", "targetPath": "/tmp/MyApp" } ] }

This id not resolve the issue either.

gdb is also present inside the devcontainer. But I don´t understand why it is required there, as the devcontainer shall be used only for building the binary, while the remote debugging shall be done from the Windows host on the VM. So the gdb in the devcontainer should not be involved at all.
Surya Amrutha Vaishnavi Lanka (INFOSYS LIMITED) 1,115 Reputation points Microsoft External Staff

2025-11-10T03:23:06.6533333+00:00

Thank you for the detailed explanation and updated configuration. Based on your workflow and the error message ( Unable to find devcontainer.json this may be due to below points. 1.Visual Studio’s remote debugging with cppgdb currently assumes that the active context is the devcontainer when the build is done inside it. 2.The debugger tries to locate devcontainer.json because it uses that file to resolve paths and environment context for deployment/debugging steps. You can use Use a Host-Based Debug Configuration. Or Separate Build and Debug Contexts
Surya Amrutha Vaishnavi Lanka (INFOSYS LIMITED) 1,115 Reputation points Microsoft External Staff

2025-11-11T12:23:25.44+00:00

Hope you're doing well! Please let us know if the issue persists or resolved. If the answer is helpful, please click "Accept Answer" and kindly approve it. If we didn't get any response from your side. we will proceed to close the thread by 14th November
J. Müller 0 Reputation points

2025-11-11T16:48:07.39+00:00

Thanks again for your feedback and hints.

Sadly they are rather increasing my confusion than creating clarity on how to resolve this issue.

If VS is assuming the devcontainer as context for initiating the debugging session, then why is it using paths from the Windows host system as seen in the Cross Platform Log above? Is there any opportunity to change or overwrite this configuration or is this simply a bug in VS?

If the devcontainer.json file is not only used to create the container but also to do some path and environment resolving inside the running container, do I need to add any possibly MS specific settings there? Checking the reference at https://containers.dev I cannot find anything looking like a fit for this task. And first of all, how can overcome the issue that VS cannot resolve the path to the file it requires for path resolving properly?

As you recommend a host-based/two-step approach now: Does this mean deployment and remote-debugging is not possible at all with current VS22 when using a devcontainer for building the project?
Surya Amrutha Vaishnavi Lanka (INFOSYS LIMITED) 1,115 Reputation points Microsoft External Staff

2025-11-17T11:57:53.7733333+00:00
Thanks for the info, here are some more possible steps

Use System.Text.Json Default in ASP.NET Core

Add using System.Text.Json.Serialization;

Annotate properties with [JsonPropertyName("propertyName")].

-Ensure the controller action uses [FromBody]

2.Use Newtonsoft.Json

Install NuGet package: Microsoft.AspNetCore.Mvc.NewtonsoftJson

In Program.cs or Startup.cs
services.AddControllers()

        .AddNewtonsoftJson(options =>

        {

            options.SerializerSettings.ContractResolver = new Newtonsoft.Json.Serialization.DefaultContractResolver();

        });

Use [JsonProperty("propertyName")] in your model

Verify the JSON payload matches the property names exactly
J. Müller 0 Reputation points

2025-11-17T14:06:49.45+00:00

As mentioned in the initial posting, this is a C++ project, there is no ASP.NET involved at all and I also don´t get the relation to JSON serialization. Could it be your comment was intended for some other thread?
Surya Amrutha Vaishnavi Lanka (INFOSYS LIMITED) 1,115 Reputation points Microsoft External Staff

2025-11-18T10:31:51.7366667+00:00
Sorry for the inconvenience, You launched the debug configuration while the Target System was set to your remote VM, but the build is configured to run in a Dev Container. In that combination Visual Studio mistakenly tries to locate the container config on the VM,here is the new solution you can try from new

In the toolbar, set “Target System” to “Dev Containers”. Do not switch the Target System to the VM for this configuration. Keep the build context in the container; the debug target will still be the VM via remoteMachineName. This mirrors the official flow.

Use a clean, minimal launch.vs.json for Linux/GDB remote debug.
Keep type "cppgdb" and debuggerConfiguration: "gdb".

remoteMachineName must reference the entry you created in Connection Manager.

program and cwd are paths on the VM.

Add a source mapping from the container’s mount path back to your Windows folder so breakpoints bind correctly.

3.check the architecture & symbols.
Ensure the Dev Container build preset actually builds an ELF for the VM’s architecture.

Confirm gdb is installed on the VM, since you’re using GDB mode (debugger runs on the target). This is the recommended mode when versions differ.
https://learn.microsoft.com/en-us/cpp/linux/deploy-run-and-debug-your-linux-project?view=msvc-170
4.Only if you need to: split presets.

Use one CMake for container build and a separate toolchain/cross preset if the VM is a different arch. Then keep the single debug configuration above.

After all this checks if the issue persists, please run the below checklist
Target System shows “Dev Containers”. If it shows “Remote Linux: MyVM”, switch it back and retry.

Add a sourceFileMap from the container path (e.g., /workspaces/myapp) to your local path (C:\src\myapp) so breakpoints bind correctly.

Ensure gdb is installed on the VM and that the binary you build in the container matches the VM’s architecture.
Surya Amrutha Vaishnavi Lanka (INFOSYS LIMITED) 1,115 Reputation points Microsoft External Staff

2025-11-20T11:46:00.93+00:00

Hope you’re doing well! Please let us know if the issue persists or resolved. If the answer is helpful, please click “Accept Answer” and kindly approve it. If we didn’t get any response from your side. we will proceed to close the thread by 21st November
J. Müller 0 Reputation points

2025-11-20T14:28:09.7166667+00:00

I really appreciate your perstisting attempts to provide help, but your comment is basically just an exact description of what I´m doing already with the results described in my initial posting. It does not identify any root cause or even a new aspect to look at, but reiterates on many topics we already clarified at an earlier stage (target is devcontainer, remoteMachineName is correct, cwd is correct, gdb is existing on the VM, ...). None of them resolved the issue previously, so why should they now? And why do you keep pushing me so hard to accept this rather vague guesses as an answer and close the topic within a deadline of only some days? Even if you cannot provide a resolution for the root cause of the issue, maybe someone else can.

Currently I´m looking into moving the debug setup into the container as well as a workaround. But it seems this comes with it´s own challenges as some direct, low-level access to the host networks is required while Dockers main pupose is to keep containers away from things like this.
Surya Amrutha Vaishnavi Lanka (INFOSYS LIMITED) 1,115 Reputation points Microsoft External Staff

2025-11-27T09:24:25.1133333+00:00
Based on your logs and the behavior you described, the issue is caused by Visual Studio mixing the build context (Dev Container) with the debug context (Remote VM). When the Target System is switched to the VM, Visual Studio expects the devcontainer.json to exist on the VM and therefore pops the “Unable to find devcontainer.json” error. This happens because Target System is set to the VM, while the build/run context stays inside the dev container.

1.Set “Target System” to Dev Containers and do not switch Target System to the VM.

Build continues inside the dev container, remote debugging still works using remoteMachineName. Visual Studio no longer tries to find devcontainer.json on the VM.

2.Use a minimal launch.vs.json specifically for GDB remote debugging

{

"version": "0.2.1",

"configurations": [

{

"name": "Debug MyApp on VM",

"type": "cppgdb",

"debuggerConfiguration": "gdb",

"MIMode": "gdb",

"remoteMachineName": "MyVM",

"program": "/tmp/MyApp",

"cwd": "/tmp",

"disableDeploy": true,

"sourceFileMap": {

"/workspaces/myapp": "C:/src/myapp"

}

}

]

}

3.Ensure architecture + symbols match between container and VM.

Dev Container must remain the Target System because:

VS uses container filesystem mappings for symbols and source if Target System is equal to VM, VS thinks the build also happens on VM

VS attempts to load devcontainer.json from VM

if it Fails you get the popup error
Surya Amrutha Vaishnavi Lanka (INFOSYS LIMITED) 1,115 Reputation points Microsoft External Staff

2025-12-01T04:54:12.3666667+00:00

Hope you're doing well! Please let us know if the issue persists or resolved. If the answer is helpful, please click "Accept Answer" and kindly approve it.
Surya Amrutha Vaishnavi Lanka (INFOSYS LIMITED) 1,115 Reputation points Microsoft External Staff

2025-12-02T10:57:49.08+00:00

We haven’t received any further updates or follow-up on this case, so we’ll proceed with closing it at this time. If you require additional assistance or have new information to share, please feel free to raise new thread, we’re happy to support you further needed.

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How to deploy and debug a program from a devcontainer on a remote system?

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