Usecase and usage are unclear

[130s]

Issue

Usecase is unclear, so is usage.

Potential resolution

Add documentation.

[130s]

Advocating the tool for some usecases

Justifying docker_vcs' usefulness for some of the potentially common usecases. Although these usecases are relatively easily achieved by the combination of a few docker CLI on the host + bash CLI inside a Docker container, it can get tedious, and little things can be easilly missed in repeated processes.

• UC-1. You already have source to work on on your host. You want to build and test-executing them inside Docker container. To start, you just want to pass the path of (catkin /) ament workspace into Docker container can be done as easy as docker run -v $PATH_HOST:/ament_ws/src. Then, the series of commands to be done in order to build the workspace may be fairly similar for many developes, doesn't it? E.g.

  source /opt/ros/$ROSDISTRO/setup.bash
  cd /ament_ws/src
  apt update && rosdep update && rosdep install --from-paths src --ignore-src -r -y
  colcon build

  • Good on a development host.
• UC-2. You don't have workspace on your host yet, all you have is x.repos file that can be used to clone multiple repositories by batch using vcstool. You just want to pass that to some tool and in return want a Docker image that contains the built packages from all repositories defined in the x.repos file.
  • Good on a CI host e.g. online dev repository.
• UC-3. In addition to x.repos file, you have a Dockerfile as you had to define some custom steps in installation and/or building.
  • Good on a CI host e.g. online dev repository where you need custom steps in installation and/or building, e.g.
    • Dependency has to be "manually" installed.
      • rosdep cannot install those packages, because the packages your package depends on are not available in rosdep database.
      • Custom apt source (i.e. /etc/apt/sources.list.d/YOUR.list in Debian/Ubuntu), key server, are needed.
    • You need a special library where installation steps are already defined in a custom executable and you need to execute it.