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Attach to running Go processes with the debugger

Last modified: 15 November 2024

In GoLand, you can attach the debugger to a running Go process on a local machine, on a remote machine, or in the Docker container.

Attach to a process on a local machine

You can debug an application that you launched from the command line. In this case, the application runs outside the IDE but on the same local machine. To debug the application, you need to open the project in the IDE and attach the debugger to the running process.

For example purposes, you can use the following Go code at github.com.

Step 1. Install the gops package

  • Open the Terminal tool window (View | Tool Windows | Terminal) and run the following command: 

    go get -t github.com/google/gops/

  • Click Run | Attach to Process (CtrlAltF5). In the notification window, click the Invoke 'go get gops' link.

    Install the gops package

Step 2. Build and run the application

  1. Open the Terminal tool window by navigating to View | Tool Windows | Terminal), and execute the following command:

    go build -gcflags="all=-N -l" -o myApp.exe

    This command compiles the myApp.exe executable and disables compiler optimizations and inlining.

  2. Run the compiled executable.

    .\myApp.exe
    Build the application with gcflags flags

note

Do not use -ldflags="all=-w" or -ldflags="-w" flags. These flags are incompatible with debugging the application because they strip out the necessary DWARF information that is required by Delve.

note

Symbolic links or symlinks are incompatible with debugging because of incompatibility between the Go toolchain, Delve, and GoLand.

Step 3. Attach to and debug the running process

  1. Click the gutter next to the line of code where you want to set the breakpoint. In the provided example, place the breakpoint on the line 23 (message := fmt.Sprintf("Hello %s!", r.UserAgent())). Read more about breakpoints in Breakpoints.

  2. Click Run | Attach to Process or use the shortcut CtrlAltF5.

  3. In the Attach with Debugger To window, select your application process and press Enter.

  4. Trigger the event associated with the breakpoint in your application. If using the provided code example, open the http://localhost:8080/ link in a browser.

Attach to a process on a remote machine

You can connect to a remote computer and attach the debugger to the Go process running on it. The remote debugger (Delve) must be running on the remote computer.

To install Delve, you can use the following command:

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

note

Ensure Delve is compiled with the same Go version as your application on the host and target machines. Slight differences in operating systems or versions can lead to unexpected debugging behavior.

Step 1. Build the application on the remote computer

  • Open the Terminal tool window (View | Tool Windows | Terminal) and run the following command:

    go build -gcflags="all=-N -l" -o myApp.exe

    This command compiles the myApp.exe executable and disables compiler optimizations and inlining.

Step 2. Run Delve on the remote machine

  • You have two options to launch the debugger on the host machine:

    • The debugger runs the process for you. If you use a firewall, expose the port that is used in the configuration (for example, 2345). You can use any port number that is not occupied. myApp is the name of the executable that was built on Step 1.

      dlv --listen=:2345 --headless=true --api-version=2 exec ./myApp

      If you need to pass arguments to the binary as-is, add the double dash sign (--) to the previous command and then necessary options (for example, -- --config=/path/to/config/file).

    • You run the process, and the debugger attaches to the running process. <PID> is the process identifier of your application. You can get the process identifier by using the Attach to Process command.

      dlv --listen=:2345 --headless=true --api-version=2 attach <PID>
    Run Delve on the host machine

Step 3. Start the debugging process on your local computer

  1. Open the code of your application and place a breakpoint. In the provided code example, set the breakpoint on line 23 (message := fmt.Sprintf("Hello %s!", r.UserAgent())). Read more about breakpoints in Breakpoints.

  2. Click Edit | Run Configurations. Alternatively, click the list of run/debug configurations on the toolbar and select Edit Configurations.

  3. In the Run/Debug Configurations dialog, click the Add button (the Add button) and select Go Remote.

  4. In the Host field, type the host IP address (for example, localhost or 192.168.1.33).

  5. In the Port field, type the debugger port that you configured on Step 2 (for example, 2345).

  6. Click Debug.

  7. Trigger the event at the breakpoint in your application. If you used the provided code example, open the http://<host_address>:8080/ link in a browser.

    On the following video, there are two IDE instances: the IDE using the dark theme is the local computer, and the IDE with the light theme is a remote computer.

Attach to a process in the Docker container

You can attach the debugger to a Go process that runs inside a Docker container. For more information about Docker, refer to Docker.

For example purposes, you can use the following Dockerfile for this Go application.

Step 1. Create a Dockerfile configuration

  1. Click Edit | Run Configurations. Alternatively, click the list of run/debug configurations on the toolbar and select Edit Configurations.

  2. In the Run/Debug Configurations dialog, click the Add button (the Add button) and select Docker | Dockerfile.

  3. In the Dockerfile field, click the Browse icon (the Browse icon) and navigate to Dockerfile in the file browser. If you use the example from this section, navigate to this Dockerfile.

  4. In the Container name field, type the container name (for example, debugging-tutorial.

  5. In the Run/Debug Configurations dialog, click Modify and select Bind ports and Run options.

    Bind ports

  6. In the Bind ports field, click Browse (the Browse icon).

  7. In the Port Bindings dialog, click the Add button (the Add button). In the Host port column, type 8080. Click the Container port column, type 8080. Additionally, create the same binding for the port 40000.

    Bind ports

  8. In the Run options field, specify command-line options for Docker. For the example provided in the Dockerfile, disable the security profile and add the SYS_PTRACE Linux capability.

    --security-opt="apparmor=unconfined" --cap-add=SYS_PTRACE

  9. Click Run.

    Create a Dockerfile configuration

Step 2. Create the Go Remote run/debug configuration

  1. Click Edit | Run Configurations. Alternatively, click the list of run/debug configurations on the toolbar and select Edit Configurations.

  2. In the Run/Debug Configurations dialog, click the Add button (the Add button) and select Go Remote.

  3. In the Host field, type the host IP address (for example, localhost).

  4. In the Port field, type the debugger port that you configured. In this example, it is 40000.

  5. Click OK.

    Create the Go Remote run/debug configuration for the Docker debugging

Step 3. Start the debugging process

  1. In the Services tool window (View | Tool Windows | Services), expand Docker | Containers. Ensure that the created container is running and listens to the preconfigured debugger port.

  2. Click the gutter near the line of code to place the breakpoint. For example, in the provided code example, put the breakpoint on the line 23 (message := fmt.Sprintf("Hello %s!", r.UserAgent())).

    Read more about breakpoints in Breakpoints.

  3. From the list of run/debug configurations on the toolbar, select the created Go Remote configuration and click the Debug <configuration_name> button (the Debug button). Alternatively, press AltShiftF9 to select the created Go Remote configuration.

  4. Trigger the event at the breakpoint in your application. If you used the provided code example, open http://localhost:8080/ in a browser.

    The following video demonstrates how to run a container, create a remote run/debug configuration, and connect to the container for debugging.

Productivity tips

Terminate the remote process

  • You can press CtrlF2 to terminate the remote process during the remote debugging session. Note that you cannot reattach to the process when you terminated it.