Step 2: Python 3.9

The Ubuntu 20.04 stable branch includes Python up to version 3.6. While oTree runs on this version, there are some bugs related to the presentation of the monitoring table. Columns appear to be scrambled. To avoid this, we install Python 3.9 from sources.

Get Python 3.9

Log in as otree and navigate to your home directory. Download and unpack Python 3.9 (any point release is fine, change the following commands accordingly):

cd ~
wget https://www.python.org/ftp/python/3.9.9/Python-3.9.9.tgz
tar  zxvf Python-3.9.9.tgz
rm Python-3.9.9.tgz

Configuration and building

Change working directory, then configure and make Python 3.9:

cd Python-3.9.9
./configure --with-ensurepip=install --enable-optimizations
make -j8

This might take a while. Time to get some coffee.

Installation

By default python points to python2.7. We will add python 3.9 as an alternative, but give the old association highest priority. We will have to use python3.9 explicitly (rather than just python or python3), but at least we are not breaking anything.

sudo make altinstall
sudo update-alternatives --install /usr/bin/python python /usr/local/bin/python3.9 40

Leave and remove working directory:

cd ..
sudo rm -rf Python3.9.9

Virtual environment

OTree will run in its own virtual environment. This allows us to keep it separate from the system Python installation and avoids dependency clutter. We will create an initial virtual environment:

python3.9 -m venv venv_otree
source venv_otree/bin/activate

Finally, we make sure that the oTree virtual environment is automatically activated whenever otree logs in:

echo "source /home/otree/venv_otree/bin/activate" >>/home/otree/.otree_env
echo "source /home/otree/.otree_env" >> /home/otree/.bashrc

This complete the second step.