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I'm working on a cloud-based robotic application with AWS RoboMaker. I'm using ROS Kinetic, with the build tool colcon.

My robot application depends on a custom python module, which has to be in my workspace. This python module is built by colcon as a python package, not a ROS package. This page explains how to do that with catkin, but this example shows how to adapt it to colcon. So finally my workspace looks like that :

my_workspace/
        |--src/
            |--my_module/
            |     |--setup.py
            |     |--package.xml
            |     |--subfolders and python scripts...
            |--some_ros_pkg1/  
            |--some_ros_pkg2/
            |...

However the command : colcon build <my_workspace> builds all ROS packages but fails to build my python module as a package.

Here's the error I get :

Starting >>> my-module
[54.297s] WARNING:colcon.colcon_ros.task.ament_python.build:Package 'my-module' doesn't explicitly install a marker in the package index (colcon-ros currently does it implicitly but that fallback will be removed in the future)
[54.298s] WARNING:colcon.colcon_ros.task.ament_python.build:Package 'my-module' doesn't explicitly install the 'package.xml' file (colcon-ros currently does it implicitly but that fallback will be removed in the future)



--- stderr: my-module                                                                     
usage: setup.py [global_opts] cmd1 [cmd1_opts] [cmd2 [cmd2_opts] ...]
   or: setup.py --help [cmd1 cmd2 ...]
   or: setup.py --help-commands
   or: setup.py cmd --help

error: invalid command 'egg_info'
---
Failed   <<< my-module [0.56s, exited with code 1]

I found this issue that seems correlated, and thus tried : pip install --upgrade setuptools ...Which fails with the error message :

Collecting setuptools
  Using cached https://files.pythonhosted.org/packages/7c/1b/9b68465658cda69f33c31c4dbd511ac5648835680ea8de87ce05c81f95bf/setuptools-50.3.0.zip
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "setuptools/__init__.py", line 16, in <module>
        import setuptools.version
      File "setuptools/version.py", line 1, in <module>
        import pkg_resources
      File "pkg_resources/__init__.py", line 1365
        raise SyntaxError(e) from e
                                ^
    SyntaxError: invalid syntax
    
    ----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-build-uwFamt/setuptools/

And with pip3 install --upgrade setuptools, I get :

Defaulting to user installation because normal site-packages is not writeable
Requirement already up-to-date: setuptools in /home/ubuntu/.local/lib/python3.5/site-packages (50.3.0)

I have both Python 3.5.2 an Python 2.7, but I don't know which one is used by colcon.

So I don't know what to try next, and what the real problem is. Any help welcome !

16Aghnar
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  • Windows or linux? What is the python version that you are using? – Roni Antonio Sep 17 '20 at 14:58
  • I'm developping on linux with AWS Cloud9. OS Ubuntu 16.04, Python 3.5.2. Note that I tried `pip install --upgrade setuptools`also with pip3, without success. I update my question with the stdout of pip3. – 16Aghnar Sep 17 '20 at 15:39
  • Oh, looks like this is a very linux specific issue. Even in the thread that you mentioned, some people decided to remove and download/install from hand some components, I think it is worth the try. For example, this one: – Roni Antonio Sep 18 '20 at 00:42
  • provided by Chirag Maliwal, which uses ubuntu as well and downloaded the zip from https://pypi.python.org/pypi/setuptools and ran the command $ sudo python ez_setup.py. I think it is worth the try. – Roni Antonio Sep 18 '20 at 00:52
  • provided by Chirag Maliwal, which uses ubuntu as well and downloaded the zip from https://pypi.python.org/pypi/setuptools and ran the command $ sudo python ez_setup.py. I think it is worth the try. – Roni Antonio Sep 18 '20 at 00:52
  • Hum, I don't find any script named ez_setup.py; neither in setuptools or anywhere else. I'm updating the question with more info about python. – 16Aghnar Sep 18 '20 at 08:09
  • Some linux images comes with python2 pre installed, it is possible to have both. I personally don't like it, only when strictly necessary. Usually the command 'python' refers to the default python2, and 'python3' or 'python37', 'python38' for newer versions. You can always run the command 'which python' to get more details. – Roni Antonio Sep 18 '20 at 17:35
  • @RoniAntonio thank you for reading and commenting ! It turns out the problem was caused by a wrong workspace tree and some mistakes in my original `setup.py`. – 16Aghnar Sep 22 '20 at 16:29

1 Answers1

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I managed to correctly install my package and its dependencies. I develop the method below, in case it may help someone someday !

I have been mainly inspired by this old DeepRacer repository.

The workspace tree in the question is wrong. It should look like this:

my_workspace/
        |--src/
            |--my_wrapper_package/
            |     |--setup.py
            |     |--my_package/
            |          |--__init__.py
            |          |--subfolders and python scripts...
            |--some_ros_pkg1/  
            |--some_ros_pkg2/
  • my_wrapper_package may contain more than one python custom package.
  • A good setup.py example is this one.
  • You shouldn't put a package.xml next to setup.py : colcon will only look at the dependencies declared in package.xml, and won't collect pip packages.
  • It may help sometimes to delete the folders my_wrapper_package generated by colcon in install/ and build/. Doing so you force colcon to rebuild and bundle from scratch.
16Aghnar
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