Set RPC Python when using elpy with virtualenv

Question

I'm having trouble getting my elpy setup to work smoothly.

My current config is:

Elpy Configuration

Virtualenv........:  (/home/jeff/Documents/Proj/myenv/bin/)
RPC Python........: 3.7.3 (/usr/bin/python3)
Interactive Python: python (/usr/bin/python)
Emacs.............: 26.1
Elpy..............: 1.28.0
Jedi..............: 0.15.1
Rope..............: 0.14.0
Autopep8..........: 1.4.4
Yapf..............: 0.28.0
Black.............: 19.10b0
Syntax checker....: flake8 (/usr/bin/flake8)

The python interactive interpreter (python) is not installed on the
current virtualenv (/home/jeff/Documents/Proj/myenv/bin/). The
system binary (/usr/bin/python) will be used instead.

[run] python3 -m pip install python

How do I get RPC Python set to use the interpreter in my virtual environment?

Answer 1

You can set elpy-rpc-virtualenv-path:

Path to the virtualenv used by the RPC.

Can be ‘default (create a dedicated virtualenv .emacs.d/elpy/rpc-venv), ‘system (use the system environment), ‘current (use the currently active environment), a virtualenv path or a function returning a virtualenv path.

If the default virtual environment does not exist, it will be created using elpy-rpc-python-command and populated with the needed packages from elpy-rpc–get-package-list.

Also see elpy-rpc-python-command.

Answer 2

I stumbled into the same problem while setting up python-emacs on macOS. After a lot of searching found that following works with a bit of manual work. In your config, place following

(use-package pyenv-mode-auto
  :ensure t
  :config
  (let ((workon-home (expand-file-name "~/.pyenv/versions")))
  (setenv "WORKON_HOME" workon-home)
  (setenv "VIRTUALENVWRAPPER_HOOK_DIR" workon-home)))

The part in the config is important. The pyenv-mode-auto doesn't work for me but I use it as a carrier for the setting.

Then activate the correct environments by

pyvenv-workon

which will offer you your virtual environment. This will force the elpy RPC to use the virtual environment.

Caveat - It seems that two projects with different virtual environments don't work with the above setting. I am still investigating this. Update on Caveat - following setting for elpy might work according to the documentation

(add-hook 'elpy-mode-hook (lambda () (elpy-shell-toggle-dedicated-shell 1)))