Visual Studio Code - Remote Debugging Bazel C++ - Unable to read file 'vscode-remote://dev- file

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I'm trying to do remote debugging of bazel project in docker. Local plugins: Remote Development Docker plugins (defined in devcontainer.json): ms-vscode.cpptools

My launch.json

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Debug",
      "type": "cppdbg",
      "MIMode": "gdb",
      "request": "launch",
      "args": [],
      "stopAtEntry": true,
      "cwd": "${workspaceFolder}",
      "program": "/root/.cache/bazel/_bazel_root/e53bbb0b0da4e26d24b415310219b953/execroot/tf_serving/bazel-out/k8-dbg/bin/tensorflow_serving/fplugin/fserve_cc",
      "externalConsole": false,
    }
  ]
}

However I'm getting an error:

Unable to open 'fserve.cc': Unable to read file 'vscode-remote://dev-container+2f55736572732f6d67756d6f77736b2f776f726b2f6f766d732d63/proc/self/cwd/tensorflow_serving/fplugin/fserve.cc

In local development I would add sourceFileMap, however it doesn't seem to work for remote docker development. Any ideas?

bazel visual-studio-code docker c++
2 Answers

when you try to compile with bazel, you will have 4 soft link(bazel-bin, bazel-{source-folder}, bazel-out, bazel-testlog) modify this attribute wi

"cwd": "${workspaceFolder}/bazel-",

user_98734530

I'm not sure that your problem is due to remote debugging. I believe that the following info will work whether or not you're in a remote environment.

Bazel generates a few symlinks in your project's root folder that contain useful data (for more see the docs):

  • bazel-bin is a symlink to a folder in the output directory that contains generated code and binaries for the latest configuration of the build you've run.
  • bazel-{folder-name} is a symlink to the execRoot, which is how bazel sees your project's source code. {folder-name} is the name of the folder your project is in.
  • bazel-out is a symlink to bazel's output root.
  • bazel-testlog is a symlink to the outputs from test runs

If you're not using bazel's runfiles library

To provide VSCode with sources at the right location, modify the "cwd" attribute in launch.json to:

"cwd": "${workspaceFolder}/bazel-{folder-name}",`

If you are using runfiles

You're using runfiles if your program requires files in a data attribute in any of its dependencies

First, set "cwd" to the root of the runfiles tree for your binary, and then set "sourceFileMap" in a way that maps the current working directory to the execRoot symlink. For me (on linux), /proc/self/cwd maps correctly, but that might not be true for you. I was able to tell that I got it wrong because VSCode complained about being unable to read a file at /proc/self/cwd/external/external-project/src/file.cpp.

"cwd": "${workspaceFolder}/bazel-bin/path/to/executable/executable.runfiles/{workspace-name}`,
"sourceFileMap": {
    "/proc/self/cwd": "${workspaceFolder}/bazel-{folder-name}`,
},

{workspace-name} can be found in WORKSPACE, it will look like workspace(name = "my-project"). If there is no workspace name defined in that file, it defaults to __main__.

I might also recommend changing the "program" attribute to a more convenient location. If the last thing you did was build your binary with bazel, you can find the built executable at bazel-bin/path/to/executable/executable

A full example:

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "(gdb) Launch Debug",
            "type": "cppdbg",
            "request": "launch",
            // path to the most recently built version of executable
            // this should be built with `bazel build -c dbg //path/to:executable`
            "program": "${workspaceFolder}/bazel-bin/path/to/executable/executable",
            "args": [],
            "stopAtEntry": false,
            "cwd": "${workspaceFolder}/bazel-bin/path/to/executable/executable.runfiles/{workspace-name}",
            "environment": [],
            "externalConsole": false,
            "MIMode": "gdb",
            "setupCommands": [
                {
                    "description": "Enable pretty-printing for gdb",
                    "text": "-enable-pretty-printing",
                    "ignoreFailures": true
                }
            ],
            "sourceFileMap": {
                "/proc/self/cwd": "${workspaceFolder}/bazel-{folder-name}"
            }
        }
    ]
}

Most of this is covered in this useful post (which also shows how to automatically build your executable using tasks.json): https://shanee.io/blog/2019/05/28/bazel-with-visual-studio-code/

user_8317680
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