Python virtual environments are used regularly by seasoned Python programmers however, beginners may not know about this feature rich tool. Virtualenv is a tool which allows the creation of isolated python environments. So what do we get from isolated environments? Lets say you are developing a project that needs version 1 of some library. You install it globally on the RPI. A while later you start work on another project that requires the same library, but version 2. If you install version 2 globally, as you did before, it will invalidate the first project you were working on. This is where virtual environments comes to the rescue, every project is in it's own isolated environment and you no longer need to install python packages as sudo (root) user. Which means the other advantage of virtual environments is that it's installed in your user account not in the root of the system.
Although this API will work with Python version 2.7.x I strongly recommend writing any new code using Python 3.8 or higher. The Python 2.x versions ware at their end of life on January 1st 2020.
First you will need to log into your Raspberry Pi with ssh. There are many good tutorials online that explain how to do this.
As the pi user (on the newer RPI OS you'll need to create your own user account) on your Raspberry Pi you will need to install a few system packages. I'm assuming you have installed Raspian bullseye. Python 2 is no longer installed on bullseye.
Change the below packages to the Python 2.x versions where appropriate.
$ sudo apt install build-essential python3-dev python3-setuptool \
git libssh-dev libffi-dev rustc-mozilla cargo-mozillaIf you'll be using pygame instead of approxeng you'll also need to install the following packages.
$ sudo apt install python3-dev python3-setuptools python3-numpy \
python3-opengl ffmpeg libsdl2-image-2.0-0 \
libsdl2-mixer-2.0-0 libsdl2-ttf-2.0-0 libsdl2-dev \
libsdl2-mixer-dev libsmpeg-dev libportmidi-dev \
libswscale-dev libportmidi-dev libswscale-dev \
libavformat-dev libavcodec-dev libtiff5-dev libx11-6 \
libx11-dev fluid-soundfont-gm timgm6mb-soundfont \
xfonts-base xfonts-100dpi xfonts-75dpi xfonts-cyrillic \
fontconfig fonts-freefont-ttfInstall the Python virtual environment. The pip utility can be used to
install packages for either python2 or python3 there is no need to
install pip for both python versions. This is also true for the virtual
environment package which can create virtual environments for either
version of Python. The virtualenvwrapper package is a wrapper around
virtualenv that provides easy to use tools for virtualenv and will
install virtualenv for you.
Note
A directory is created in the user's home directory named
.virtualenvs. In there you'll be able to find all your project
requirements and the packages you have installed for each of them.
$ sudo easy_install3 pip
# Newer systems no longer have ``easy_install`` for Python 3
# installed, however, I have found the command below to work.
$ sudo python3 /usr/lib/python3/dist-packages/setuptools/command/easy_install.py pip
$ sudo -H pip3 install virtualenvwrapperConfigure .bashrc in the pi user directory to auto load the
virtualenvwrapper package.
$ nano .bashrcThen add the following lines to the bottom of the .bashrc file.
# Setup the Python virtual environment.
VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3
source /usr/local/bin/virtualenvwrapper.sh
$ . .bashrcCreate a VE (Virtual Environment) for your project. The VE name can be whatever you want and does not need to match the actual project's name, but it might be a good idea to keep it short so that you can remember it.
$ cd /path/to/your_project
$ mkvirtualenv your_project # mkvirtualenv -p python2 your_projectAfter the initial creation of the VE you can use these commands to activate and deactivate a VE.
$ workon <your_project>
$ deactivateNext you will need to install all the Python packages that your project depends on. Many of them will be in the pip repository at PyPi Repository.
To install python-thunderborg in your virtual environment enter the
following on the command line. Be sure your virtual environment is activated
before doing this.
$ pip install python-thunderborg
or
$ pip install git+https://github.com/cnobile2012/python-thunderborg.gitIf you are working on python-thunderborg itself, then
python-thunderborg is the project you are working on and you'll need to
install the development.txt file mentioned below. You may want to fork my
version first. This is advanced usage you and will need to have your own git
account for this to work properly.
$ cd /path/to/where/your/project/will/be/rooted
$ git clone [email protected]:cnobile2012/python-thunderborg.gitIf all the correct system packages have been installed you can now setup the
virtual environment that python-thunderborg requires.
There are three pip files that can be used approxeng.txt, pygame.txt,
or development.txt. Unless you will be mofiying the python-thunderborg
code itself you will not need the development.txt file. I recommend
installing ipython, it has a much better command line interface than the
one you get from Python itself. The development.txt does this for you.
$ workon <your_project>
$ pip install -r requirements/approxeng.txt
$ pip install ipython # If needed, it's included in development.txt.That should be it. If you have any issues please check all the instructions before contacting me.
This is just an example of how to start an app on reboot my actual code below will probably not work on your system.
Run the crontab app.
$ crontab -eThen add the line below to your user cron file. Remember to change the <username> to your username.
@reboot /home/<username>/bin/start_mborg_approxeng.shCopy the start_mborg_approxeng.sh script.
$ cd # Make sure you're in your home directory.
$ mkdir bin
$ cd /path/to/python-thunderborg
$ cd scripts/start_mborg_approxeng.sh ~/bin/