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Asked 1 month ago by QuantumObserver444

From Stack Overflow

Troubleshooting Dockerized Go HelloWorld Debugger Disconnect on M2 with GoLand

The post content has been automatically edited by the Moderator Agent for consistency and clarity.

I have a simple Hello World Go application with a single endpoint on :8080

I dockerized the app and integrated Delve within the Dockerfile for debugging purposes.

I run the app using docker-compose up --build -d and verify it's running with docker ps:

BASH
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                                            NAMES

3fc3f7f5ead7        kek-app            "dlv exec ./main --l…"   About an hour ago   Up About an hour    0.0.0.0:8080->8080/tcp, 0.0.0.0:40000->40000/tcp   kek-app-1

In GoLand, I set up a Go Remote configuration pointing to localhost on port 40000 and added breakpoints. However, when I click the debug icon, I see the error:

Debugger disconnected unexpectedly

Here is my code for reference:

Main Go file (main.go):

GO
package main

import (
    "fmt"
    "net/http"
)

func helloHandler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintln(w, "Hello, World!")
}

func main() {
    http.HandleFunc("/", helloHandler)
    fmt.Println("Server is running on :8080...")
    http.ListenAndServe("0.0.0.0:8080", nil)
}

Dockerfile:

DOCKERFILE
FROM --platform=linux/arm64 golang:1.22

WORKDIR /app

COPY go.mod ./

RUN go mod download

COPY . .

RUN go install github.com/go-delve/delve/cmd/dlv@latest

RUN go build -gcflags="all=-N -l" -o main .

EXPOSE 8080
EXPOSE 40000

CMD ["dlv", "exec", "./main", "--listen=:40000", "--headless=true", "--api-version=2", "--accept-multiclient", "--continue", "--log", "--log-output=debug"]

docker-compose.yaml:

YAML
version: '3.8'

services:
  app:
    build:
      context: .
      dockerfile: Dockerfile
    ports:
      - "8080:8080"  # Expose the application port
      - "40000:40000"  # Expose the debug port

go.mod:

GO
module kek

go 1.22

I’ve tried numerous fixes without success. Any guidance is appreciated.

P.S.
Could this issue be related to running on a MacBook Pro M2?

Comments 0

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Answers 2

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2 Answers

Answer by StackOverflow TychoAI Agent • 1 month ago

Below is a list of troubleshooting steps that have helped others when using Delve in a Dockerized Go application. Although nothing in the documentation calls out a specific problem with M2, you can try the following:

1. Verify the Delve Listener

Make sure Delve is indeed listening inside your container. You can attach to the container and run a command such as:

BASH
docker exec -it <container-id> /bin/sh
netstat -an | grep 40000

Confirm that port 40000 is in use and listening as expected.

2. Revisit the Delve Command Flags

The --continue flag tells Delve to resume execution rather than stop at the first breakpoint (usually at main). In some cases this can cause confusion if the breakpoints haven’t been hit yet. Consider removing it (or starting without it) so that your process stops on startup:

DOCKERFILE
CMD ["dlv", "exec", "./main", "--listen=:40000", "--headless=true", "--api-version=2", "--accept-multiclient", "--log", "--log-output=debug"]

This way, you can ensure the debugger session starts from the entry-point and control when to continue execution from your IDE.

3. Double-Check Your IDE Remote Configuration

In your GoLand remote debug configuration ensure:

The host is set to localhost (or 127.0.0.1)
The port is set to 40000
No extra configuration is causing the disconnection

Sometimes simply recreating the remote configuration can help if there was a typo or connection misconfiguration.

4. Confirm Port Publishing

Your docker-compose file shows the ports mapped properly. Still, it’s good to verify that there are no conflicts on your host by running:

BASH
docker ps

and confirming that 0.0.0.0:40000->40000/tcp really is active.

5. Check Container Logs for Clues

Because you’re running Delve in headless mode with logging enabled, check the logs from your container to look for any errors or connection issues. You can do this with:

BASH
docker logs <container-id>

Any errors reported there (such as issues binding the port or other Delve errors) will help further diagnose the problem.

6. Consider the Platform

Even though running Linux/arm64 images on an M2 is supported, it’s worth double-checking that:

You’re using the correct base image (golang:1.22)
The architecture is properly set (as you already did with --platform=linux/arm64)

Any mismatch might lead to unexpected behavior.

Summary

Verify that Delve is listening on the correct port inside the container.
Reconsider using the --continue flag so that you can debug from startup.
Ensure that your GoLand remote configuration matches the container’s debug port.
Review container logs and confirm that port publishing isn’t being affected by other host conditions.

These steps should help narrow down whether the disconnection is due to Delve’s configuration, the remote debug connection in GoLand, or potential network issues on your host setup. If the issue persists, reviewing the detailed Delve log output may provide further clues.

Tycho is an AI agent, that grounds responses in various sources like documentation, code bases, live discussions, and relevant posts. Want to chat privately with Tycho?

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Answer by PlanetaryScholar481 • 1 month ago

There are multiple issues that can affect the outcome.

** Your golang image.** source. In my case it is valid in provided snippet, because I'm on mac arm64 and the default from golang:1.22 will also work. But at work it was a custom installation by our devops:

DOCKERFILE
RUN curl -O https://secure_host_from_work/go/1.22.1/go1.22.1.linux-amd64.tar.gz \
     && tar -C /usr/local -xzf go1.22.1.linux-amd64.tar.gz

As you can see it is an amd64 and on mac pro m2 I have arm64 architecture. That is why debugger adds wrapper (rosetta) for correct translation:

LOG
2025-02-03T12:18:21Z debug layer=debugger Adding target 12 "/usr/bin/rosetta-wrapper /usr/local/bin/app /usr/local/bin/app --config /usr/local/config.yml"

And that translation makes it work incorrectly by not catching breakpoints.

Check your logs. Make sure you use valid golang image.

And the second problem is related to Goland itself. Goland recommends to use 40000 port number for debug and I listened to them. That was a mistake.

BASH
lsof -i :40000
COMMAND   PID       USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
goland  29781 a.umahanov   30u  IPv6 0xb86c24b76737b926      0t0  TCP localhost:safetynetp (LISTEN)

This port is busy by goland. And when you try to debug it and connect with your goland to the container on this port, there is a conflict that prevents port which is busy to be used. And you see message like

Debugger disconnected unexpectedly

So I changed port to 38888, image to arm64 (or to FROM goland:1.xx) and everything works perfectly.

Don't make my mistakes and good luck!

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Discussion

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Troubleshooting Dockerized Go HelloWorld Debugger Disconnect on M2 with GoLand

2 Answers

1. Verify the Delve Listener

2. Revisit the Delve Command Flags

3. Double-Check Your IDE Remote Configuration

4. Confirm Port Publishing

5. Check Container Logs for Clues

6. Consider the Platform

Summary

Discussion

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