vscode-go not outputting stdout to debug console when attaching to remote docker

[mumin]

Hi all,

It seems that debugging in a remote dlv instance via docker works, but does not show stdout in the debug console.
I am just using a toy example pasted below to reproduce. This issue persists with both dlp-dap and legacy debug adapters.

System info:

Version: 1.93.1 (user setup)
Commit: 38c31bc77e0dd6ae88a4e9cc93428cc27a56ba40
Date: 2024-09-11T17:20:05.685Z
Electron: 30.4.0
ElectronBuildId: 10073054
Chromium: 124.0.6367.243
Node.js: 20.15.1
V8: 12.4.254.20-electron.0
OS: Windows_NT x64 10.0.22631 (WSL2)
WSL version: 2.2.4.0
Kernel version: 5.15.153.1-2
WSLg version: 1.0.61
MSRDC version: 1.2.5326
Direct3D version: 1.611.1-81528511
DXCore version: 10.0.26091.1-240325-1447.ge-release
Windows version: 10.0.22631.4169
Distributor ID: Ubuntu
Description:    Ubuntu 22.04.4 LTS
Release:        22.04
Codename:       jammy

dockerfile.debug

# Start from the official Golang base image
FROM golang:1.23-alpine

# Set the Current Working Directory inside the container
WORKDIR /app

# Download all dependencies. Dependencies will be cached if the go.mod and go.sum files are not changed
ENV CGO_ENABLED=0
RUN go install -ldflags "-s -w -extldflags '-static'" github.com/go-delve/delve/cmd/dlv@latest

# Copy go mod and sum files
# not used atm
# COPY go.mod ./
# COPY go.sum ./
# RUN go mod download

# Copy the source from the current directory to the Working Directory inside the container
COPY . .
RUN go build -gcflags "all=-N -l" -o test-api ./cmd

CMD [ "/go/bin/dlv", "--listen=:4001", "--headless=true", "--continue", "--log=true", "--accept-multiclient", "--api-version=2", "exec", "/app/test-api" ]

tasks.json

{
    "version": "2.0.0",
    "tasks": [
        {
            "type": "shell",
            "command": "docker build ${workspaceFolder}/api -t test-api-debug -f ${workspaceFolder}/api/dockerfile.debug",
            "label": "api-debugging-container-build",
        },
        {
            "type": "shell",
            "label": "api-debugging-container-up",
            "isBackground": true,
            "command": "docker run -p 8001:8001 -p 4001:4001 test-api-debug",
            "dependsOn": [
                "api-debugging-container-build"
            ],
            "problemMatcher": [
                {
                    "pattern": [
                        {
                            "regexp": ".",
                            "file": 1,
                            "location": 2,
                            "message": 3
                        }
                    ],
                    "background": {
                        "activeOnStart": true,
                        "beginsPattern": ".",
                        "endsPattern": ".",
                    }
                }
            ]
        },
        {
            "type": "shell",
            "label": "api-debugging-container-down",
            "command": "docker stop $(docker ps -a -q --filter ancestor=test-api-debug) && docker rm $(docker ps -a -q --filter ancestor=test-api-debug)",
        }
    ],
}

launch.json

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Docker Debug",
            "type": "go",
            "debugAdapter": "dlv-dap", // issue exists with both dap and legacy adapters
            "request": "attach",
            "mode": "remote",
            "port": 4001,
            "showLog": true,
            "preLaunchTask": "api-debugging-container-up",
            "postDebugTask": "api-debugging-container-down",
            "substitutePath": [
                {
                    "from": "${workspaceFolder}/api",
                    "to": "/app"
                },
            ],
        },
    ]
}

./api/cmd/api.go

package main

import (
	"fmt"
	"net/http"
)

func main() {
	fmt.Println("Starting server at port 8001")

	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		fmt.Println("Request received")
		fmt.Fprintf(w, "Hello, World!")
	})

	if err := http.ListenAndServe(":8001", nil); err != nil {
		fmt.Println(err)
	}
}

[auxmoney-tbarcala]

I believe this might be a limitation in delve itself, cause when I run dlv connect 127.0.0.1:2345 I can only see the output of the program in the terminal where the dlv debug was started.

[Kabingeran]

Will docker be supported, something like /usr/local/bin/docker exec container go ?

[firelizzard18]

@auxmoney-tbarcala is correct, this is a limitation of delve, not vscode-go