Self-made Virtualenv Wrapper

Not long ago I've switched from virtualenvwrapper to self-made solution based on this idea by datagrok. It works pretty well for me and I'd like to share it here.

The idea is to have a root directory ($HOME/_dev in my case) for all projects and to have shell helper to easily jump into any project and to automatically activate it's virtualenv if it exists.

Here is how it looks in bash:

[local] [egorov@asus 11:33:19]:~  $ dev blog
Virtual environment found in /home/egorov/_dev/blog/env, activated.
(blog) [local] [egorov@asus 11:34:31]:~/_dev/blog git:master= $

Besides just jumping into directory I wanted to have tab autocompletion and easy way to create new projects home directory:

# autocompletion
[local] [egorov@asus 11:43:01]:~  $ dev service-  # tab hitted twice
service-account   service-feedback  service-products  service-workers

# new project home
[local] [egorov@asus 11:52:08]:~  $ dev rogue
mkdir: created directory '/home/egorov/_dev/rogue'
No virtual environment found, skipping activate.
[local] [egorov@asus 11:52:25]:~/_dev/rogue  $

So, here are bash helpers which should be placed somewhere inside ~/.bashrc or ~/.bash_profile (mine lives there). _dev function depends on inve shell script which must be available in PATH (I have $HOME/bin in PATH for this and inve lives there).

# dev
DEV=${HOME}/_dev  # home for all projects

_dev() {
    local p=${DEV}/$1
    [ ! -d $p ] && mkdir $p
    cd $p
    inve  # binary file to be accessible in PATH
    return 0
}
_dev_complete()
{
    local cur prev opts
    local p=${DEV}
    [ ! -d $p ] && `which mkdir` $p
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    prev="${COMP_WORDS[COMP_CWORD-1]}"
    opts=`cd $p && find -L . -maxdepth 1 -type d | sed 's|[\./]||g'`

    COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
}
alias dev=_dev
complete -F _dev_complete dev

inve executable content:

#!/usr/bin/env bash

# tuned idea from: https://gist.github.com/datagrok/2199506
#
# inve
#
# For use with Ian Bicking's virtualenv tool. Attempts to find the root of
# a virtual environment and activate it in subshell.

# First, locate the root of the current virtualenv
cwd=$PWD
export DEV_ROOT=$cwd

while [ "$PWD" != "/" ]; do
    # Stop here if this the root of a virtualenv
    # will look for virtualenv in `current dir` or in `env` subdirectory
    if [ \
        -x bin/python \
        -a -e lib/python*/site.py \
        -a -e include/python*/Python.h ]
    then
        export VIRTUAL_ENV="$PWD"
        break
    elif [ \
        -x env/bin/python \
        -a -e env/lib/python*/site.py \
        -a -e env/include/python*/Python.h ]
    then
        export VIRTUAL_ENV="$PWD/env"
        break
    fi
    cd ..
done
if [ "$PWD" = "/" ]; then
    export PATH="$cwd/node_modules/.bin:$PATH"
    echo "No virtual environment found, skipping activate." >&2
    cd $cwd
else
    # Activate
    export PATH="$VIRTUAL_ENV/bin:$cwd/node_modules/.bin:$PATH"
    unset PYTHONHOME
    echo "Virtual environment found in ${VIRTUAL_ENV}, activated." >&2
fi
exec "$SHELL"

inve script looks for virtualenv in env subdirectory or attempts to find it somewhere upper in the filesystem tree. It modifies PATH prepending $VIRTUALENV/bin and node_modules/.bin directories and starts new shell. I like the idea of starting a new subshell in order to activate virtualenv as this way we can be sure there will be no problems with PATH within shell and it's pretty safe to exit this subshell and have parent shell clean as it should be.

To easily navigate to some directories within activated virtualenv I have a couple of bash aliases defined:

alias cdsrc='cd ${VIRTUAL_ENV}/src'
alias cdsitepackages='cd ${VIRTUAL_ENV}/lib/python*/site-packages/'
alias cdproject='cd ${DEV_ROOT:-VIRTUAL_ENV}; if [ `basename ${PWD}` = "env" ]; then cd ..; fi'

This approach allows me to have virtual environments using python2 or python3 under single root directory and to have single tool to jump into project be it python2, python3 or even nodejs project.

Everything works pretty good for me.