This repository illustrates how to debug into a Docker container running a Go binary.

Prerequisites:

• Go
• Visual Studio Code
• Delve, the debugger for Go
• Docker and Docker Compose

1. Build the Go binary (for Linux) by running make
2. Build the Docker container by running docker-compose up --build
3. Open the code in Visual Studio by running code .
4. Set some breakpoints in the code
5. Start Debug into Docker in the Debug section of VS Code
6. Open http://localhost:8080 in your browser
7. See the breakpoints being hit
8. Profit!

Now, the application is a simply webserver that prints the current time on every page refresh. By default, it runs on http://localhost:8080.

The Dockerfile however won't start the executable. Instead, it will install the delve debugger and start it in headless mode. In addition to the application port 8080, it will open a debugger port at 2345.

When starting a VS Code debugging session, it will connect to that port 2345 and will make the debugger start the application. So now you can hit http://localhost:8080 and breakpoints should work as expected.

Notice that when you stop the debugger, the container will also be shut down and you might want to restart it.

[1] Remote debugging Go code with VS Code: https://github.com/Microsoft/vscode-go/wiki/Debugging-Go-code-using-VS-Code#remote-debugging

MIT.