Using org-babel to enable virtualenv

Question

I hoped to enable a virtualenv with org-babel source block before executing some python.

I wanted to do something like pyenv pyvenv-workon before it evaulates my code block. I didn't want to have to manually enable the virtualenv.

Something like,

#+NAME: elasticsearch_dsl_test
#+BEGIN_SRC: python :prologue "(pyvenv-workon 'elasticsearch)"
from elasticsearch import Elasticsearch
from elasticsearch_dsl import Search, Q

client = Elasticsearch()

search = Search(using=client, index="localdev-news-newsentry")
response = search.execute()

print ["No response", "Was successfull"][int(response.success())]
print "Response took {0}ms.".format(response.took)
#+END_SRC

I couldn't quite get it working.

Answer 1

I got this working with multiple virtualenvs concurrently using org-babel :session and pyvenv.

Note that scratchenv-SNmPgRMB is the name of one of my personal environments created using pipenv replace it with your virtualenv environment name.

#+BEGIN_SRC elisp :session venv-scratch
(pyvenv-workon "scratchenv-SNmPgRMB")
#+END_SRC

#+RESULTS:

#+BEGIN_SRC sh :session venv-scratch
echo $VIRTUAL_ENV
which python
#+END_SRC

#+RESULTS:
: /home/costrouc/.virtualenvs/scratchenv-SNmPgRMB
: /home/costrouc/.virtualenvs/scratchenv-SNmPgRMB/bin/python

#+BEGIN_SRC python :results output :session venv-scratch
import sys
print('\n'.join(sys.path))
#+END_SRC

#+RESULTS:
: 
: /home/costrouc/.virtualenvs/scratchenv-SNmPgRMB/lib/python36.zip
: /home/costrouc/.virtualenvs/scratchenv-SNmPgRMB/lib/python3.6
: /home/costrouc/.virtualenvs/scratchenv-SNmPgRMB/lib/python3.6/lib-dynload
: /usr/lib/python3.6
: /home/costrouc/.virtualenvs/scratchenv-SNmPgRMB/lib/python3.6/site-packages

Read paragraph if you need multiple concurrent virtualenvs. One important thing to note about this approach is that you must run the shell and python interpreter once before adding another session with a different virtual environment. The reasoning for this is that when org-babel starts a session for sh and python it launches an interpreter. This means that at a minimum you need to run these three blocks before starting a new virtualenv session.