Debugging C++ in a Docker Container with CLion

Note: Source code is modified from Cornell CS 5450 course material.

Update December 2018: this repository has been updated after the Clion 2018.3 release, which adds native remote debugging support. Check out the official guide It makes a debugger's life much easier. HOORAY!

This repository provides a minimal C++ project setup and the Dockerfile that allows developers to debug code in a Docker container using JetBrain Clion IDE.

Debugging in a container has many benefits, especially if you are developing Linux applications on OS X.

• It allows a consistent environment for both development and deployment;
• Developers are free from installing dependencies on their development machine. Some packages cannot be easily installed on OS X.
• The container can be launched on your development machine, or on a remote server.

Introduction

All application code, as well as its dependencies, will be installed, compiled, and ran within the container. Then, we launch a gdbserver to allow remote debugging outside of the container.

Clion supports remote debugging feature since 2018.3.

The container has a long running ssh server process, such that the container can be placed on a remote host.

The container exposes 2 ports. 7777 is for gdbserver connection. 22 for the ssh server. To avoid trouble when the container is launched on the development machine, the container 22 port is mapped to host 7776 port. This can be changed to any arbitrary number in docker-compose.yml.

Prerequisites

On your development machine, you must have a CLion IDE (2018.3 or above) installed,

On the host machine of your container (which can be the development machine), the latest Docker CE installation would be sufficient.

Usage

To debug the example, follow the following steps. If you have any problem, please refer to the official tutorial before opening an issue.

0. Import the project into CLion using the provided CMakeLists.txt.

1. Build the container.

   docker build -t liuempire/docker_clion_dev .

2. Launch the container with docker-compose.

   docker-compose up -d

   After this step, the container is running with an ssh server daemon. Clion will automatically run/test/debug via an ssh connection. The folder where docker-compose.yml locates will be the mapped to /home/debugger/code within the container. CLion will not use this mapped directory.

3. Configure the container toolchain in Clion. Go to Settings/Preferences | Build, Execution, Deployment | Toolchains, configure the container as a remote host. The username is debugger. The password is pwd. The completed configurations should be similar to the following:

4. Configure the container CMake settings in CLion. Go to Settings/Preferences | Build, Execution, Deployment | CMake, add a container CMake profile:

5. Check the file mapping settings in Clion. Before each run, code will be rsync-ed to the container at a temporary location. The following configuration should be generated automatically after the previous two steps:

6. In your Clion, you should be able to select Debug-Local container in before execution.

7. Add breakpoints in Clion. Happy debugging!

To stop the container, run docker-compose down.

Customization

• Add dependency installation scripts to Dockerfile.
• Replace CMakeLists.txt with your customized project CMakeLists.txt.