ud3tn/doc/python-venv.md

Python 3 virtualenv Setup

Multiple functional tests as well as the integration test toolchain in the µPCN project are using Python scripts to speed up development compared to pure C test implementations. The scripts are located in the tools/ directory. The integration test toolchain can be found in the test/integration/ directory. Both leverage a Python 3 implementation of several DTN protocols and convergence layers, provided in the pyupcn/ directory.

A venv is used to isolate the µPCN Python environment from the system. The Makefile target virtualenv creates a default Python virtualenv including pip and all required Python packages.

make virtualenv

The location of the virtualenv directory can be controlled with the VENV parameter. The default directory is .venv/.

make VENV=path/to/venv virtualenv

After the virtualenv is created the activate script has to be sourced to add the virtualenv Python interpreter to the PATH variable. Alternatively, environment switcher like direnv (see below) or virtualenvwrapper can be used.

source .venv/bin/activate

The tools/ directory is added to the virtualenv site-packages allowing the import of packages residing in tools/ like the pyupcn package, e.g.

from pyupcn.bundle7 import serialize_bundle7

serialize_bundle7("dtn:GS1", "dtn:GS2", b"Hello world!")

Optional: direnv support

direnv is an environment switcher loading environtal variables depending on the current directory. It can be used to automatically create and load Python virtualenvs. This is an example .envrc file making use of the Makefile virtualenv target.

layout_virtualenv() {
    local venv=$1
    if [ ! -d "${venv}" ]; then
        make virtualenv
    fi
    source ${venv}/bin/activate
}

layout virtualenv .venv