Pipenv: promises a lot, delivers very little

pipenv

Pipenv is a Python packaging tool that does one thing reasonably well — application dependency management. However, it is also plagued by issues, limitations and a break-neck development process. In the past, Pipenv’s promotional material was highly misleading as to its purpose and backers.

In this post, I will explore the problems with Pipenv. Was it really recommended by Python.org? Can everyone — or at least, the vast majority of people — benefit from it?

(This post has been updated in February 2020 and May 2020 to reflect the current state of Pipenv.)

A 2020 update (updated)

This blog post was written in 2018, and it’s still pretty accurate when it comes to the criticisms of Pipenv, but something else happened since then.

No release was made between November 2018 and May 2020. Pipenv was effectively dead for 1.5 years, and the state of Pipenv maintenance is alarming.

A release of Pipenv was made in late 2018 (aptly named v2018.11.26). But then, there was silence. New commits were made (on the order of 600-700 by the end of the year). People asked for new releases, in more or less strong words, in May 2019, then in October, and again in December. Many people — including yours truly, in this post — considered Pipenv dead. On 13th December 2019, the current maintainer claimed a new release is almost finished.

Pipenv 2019/2020 was vaporware for five months. Not much progress was made since the December post until March 2020, when an issue from 2018 was renamed the March 2020 Release Tracking Issue. Some progress was happening, and many release dates were given, but delays stacked up. March became April. The first beta release was promised by 21st April, it was delayed until the 29th. The final release was scheduled for a week from that, but it didn’t happen. Finally, Beta 2 came out on 20th May 2020, and the final release landed as v2020.5.28.

If you read further into the post, you’ll encounter a chapter titled The break-neck pace of Pipenv. Am I being a hypocrite right now? No, not at all. Projects that are being depended on, such as a package manager, should have clear policies about how they’re maintained. A new release when the maintainer feels like adding a feature is too often. A new release every 1.5 years is not often enough. And silence from maintainers, when faced with questions about releases, is simply unacceptable. Pip, for example, has updates every few months in a fairly stable pace (with the exception of emergency bugfix releases), and pip has years of development behind it, unlike the fairly new Pipenv.

And even if the May release was successful, you can’t be sure about any future releases, and what will happen with Pipenv. At the same time, Pipenv isn’t a good tool, as this post tries to explain — those criticisms are still valid, since they are at the core of what Pipenv is. Instead, perhaps consider using pip-tools for locking dependencies? It does one thing, and one thing well. It doesn’t enforce any specific structures on users, and supports any workflow you have. (If you don’t need to lock dependencies, pip + venv will suffice.)

What pipenv does

We’ve already learned that Pipenv is used to manage application dependencies. Let’s learn what that term really means.

Application dependencies

Here is an example use case for Pipenv: I’m working on a website based on Django. I create ~/git/website and run pipenv install Django in that directory. Pipenv:

  • automatically creates a virtualenv somewhere in my home directory

  • writes a Pipfile, which lists Django as my dependency

  • installs Django using pip

  • proceeds to write Pipfile.lock, which stores the exact version and source file hash [2] of each package installed (including pytz, Django’s dependency).

The last part of the process was the most time consuming. At one point, while locking the dependency versions, Pipenv hangs for 46 seconds. This is one of Pipenv’s notable issues: it’s slow. Of course, this isn’t the only one, but it defintely doesn’t help. Losing 46 seconds isn’t much, but when we get to the longer waits in the timing test section later, we’ll see something that could easily discourage users from using a package.

Running scripts (badly)

But let’s continue with our workflow. pipenv run django-admin startproject foobanizer is what I must use now, which is rather unwieldy to type, and requires running pipenv even for the smallest things. (The manage.py script has /usr/bin/env python in its shebang.) I can run pipenv shell to get a new shell which runs the activate script by default, giving you the worst of both worlds when it comes to virtualenv activation: the unwieldiness of a new shell, and the activate script, which the proponents of the shell spawning dislike.

Using pipenv shell means spawning a new subshell, executing the shell startup scripts (eg. .bashrc), and requiring you to exit with exit or ^D. If you type deactivate, you are working with an extra shell, but now outside of the virtualenv. Or you can use the --fancy mode that manipulates $PATH before launching the subshell, but it requires a specific shell configuration, in which $PATH is not overridden in non-login shells — and also often changing the config of your terminal emulator to run a login shell, as many of the Linux terminals don’t do it.

Now, why does all this happen? Because a command cannot manipulate the environment of the shell it spawns. This means that Pipenv must pretend what it does is a reasonable thing instead of a workaround. This can be solved with manual activation using source $(pipenv --venv)/bin/activate (can be made into a neat alias), or shell wrappers (similar to what virtualenvwrapper does).

Finishing it all up

Anyway, I want a blog on my site. I want to write them in Markdown syntax, so I run pipenv install Markdown, and a few long seconds later, it’s added to both Pipfiles. Another thing I can do is pipenv install --dev ipython and get a handy shell for tinkering, but it will be marked as a development dependency — so, not installed in production. That last part is an important advantage of using Pipenv.

When I’m done working on my website, I commit both Pipfiles to my git repository, and push it to the remote server. Then I can clone it to, say, /srv/website. Now I can just pipenv install to get all the production packages installed (but not the development ones — Django, pytz, Markdown will be installed, but IPython and all its million dependencies won’t). There’s just one caveat: by default, the virtualenv will still be created in the current user’s home directory. This is a problem in this case, since it needs to be accessible by nginx and uWSGI, which do not have access to my (or root’s) home directory, and don’t have a home directory of their own. This can be solved with export PIPENV_VENV_IN_PROJECT=1. But note that I will now need to export this environment variable every time I work with the app in /srv via Pipenv. The tool supports loading .env files, but only when running pipenv shell and pipenv run. You can’t use it to configure Pipenv. And to run my app with nginx/uWSGI, I will need to know the exact virtualenv path anyway, since I can’t use pipenv run as part of uWSGI configuration.

What pipenv doesn’t do

The workflow I mentioned above looks pretty reasonable, right? There are some deficiencies, but other than that, it seems to work well. The main issue with Pipenv is: it works with one workflow, and one workflow only. Try to do anything else, and you end up facing multiple obstacles.

Setup.py, source distributions, and wheels

Pipenv only concerns itself with managing dependencies. It isn’t a packaging tool. If you want your thing up on PyPI, Pipenv won’t help you with anything. You still need to write a setup.py with install_requires, because the Pipfile format only specifies the dependencies and runtime requirements (Python version), there is no place in it for the package name, and Pipenv does not mandate/expect you to install your project. It can come in handy to manage the development environment (as a requirements.txt replacement, or something used to write said file), but if your project has a setup.py, you still need to manually manage install_requires. Pipenv can’t create wheels on its own either. And pip freeze is going to be a lot faster than Pipenv ever will be.

Working outside of the project root

Another issue with Pipenv is the use of the working directory to select the virtual environment. [3] Let’s say I’m a library author. A user of my foobar library has just reported a bug and attached a repro.py file that lets me reproduce the issue. I download that file to ~/Downloads on my filesystem. With plain old virtualenv, I can easily confirm the reproduction in a spare shell with:

$ ~/virtualenvs/foobar/bin/python ~/Downloads/repro.py

And then I can launch my fancy IDE to fix the bug. I don’t have to cd into the project. But with Pipenv, I can’t really do that. If I put the virtualenv in .venv with the command line option, I can type ~/git/foobar/.venv/bin/python ~/Downloads/repro.py. If I use the centralized directory + hashes thing, Tab completion becomes mandatory, if I haven’t memorized the hash.

$ cd ~/git/foobar
$ pipenv run python ~/Downloads/repro.py

What if I had two .py files, or repro.py otherwise depended on being in the current working directory?

$ cd ~/git/foobar
$ pipenv shell
(foobar-Mwd1l2m9)$ cd ~/Downloads
(foobar-Mwd1l2m9)$ python repro.py
(foobar-Mwd1l2m9)$ exit  # (not deactivate!)

This is becoming ugly fairly quickly. Also, with virtualenvwrapper, I can do this:

$ cd ~/Downloads
$ workon foobar
(foobar)$ python repro.py
(foobar)$ deactivate

And let’s not forget that Pipenv doesn’t help me to write a setup.py, distribute code, or manage releases. It just manages dependencies. And it does it pretty badly.

Nikola

I’m a co-maintainer of a static site generator, Nikola. As part of this, I have the following places where I need to run Nikola:

  • ~/git/nikola

  • ~/git/nikola-site

  • ~/git/nikola-plugins

  • ~/git/nikola-themes

  • ~/website (this blog)

  • /Volumes/RAMDisk/n (demo site, used for testing and created when needed, on a RAM disk)

That list is long. End users of Nikola probably don’t have a list that long, but they might just have more than one Nikola site. For me, and for the aforementioned users, Pipenv does not work. To use Pipenv, all those repositories would need to live in one directory. I would also need to have a separate Pipenv environment for nikola-users, because that needs Django. Moreover, the Pipfile would have to be symlinked from ~/git/nikola if we were to make use of those in the project. So, I would have a ~/nikola directory just to make Pipenv happy, do testing/bug reproduction on a SSD (and wear it out faster), and so on… Well, I could also use the virtualenv directly. But in that case, Pipenv loses its usefulness, and makes my workflow more complicated. I can’t use virtualenvwrapper, because I would need to hack a fuzzy matching system onto it, or memorize the random string appended to my virtualenv name. All because Pipenv relies on the current directory too much.

Nikola end users who want to use Pipenv will also have a specific directory structure forced on them. What if the site serves as docs for a project, and lives inside another project’s repo? Two virtualenvs, 100 megabytes wasted. Or worse, Nikola ends up in the other project’s Pipfile, which is technically good for our download stats, but not really good for the other project’s contributors.

The part where I try to measure times

Pipenv is famous for being slow. But how slow is it really? I put it to the test. I used two test environments:

  • Remote: a DigitalOcean VPS, the cheapest option (1 vCPU), Python 3.6/Fedora 28, in Frankfurt

  • Local: my 2015 13” MacBook Pro (base model), Python 3.7, on a rather slow Internet connection (10 Mbps on a good day, and the test was not performed on one of them)

Both were runninng Pipenv 2018.7.1, installed from pip.

And with the following cache setups:

  • Removed: ~/.cache/pipenv removed

  • Partial: rm -rf ~/.cache/pipenv/depcache-py*.json ~/.cache/pipenv/hash-cache/

  • Kept: no changes done from previous run

Well, turns out Pipenv likes doing strange things with caching and locking. A look at the Activity Monitor hinted that there is network activity going on when Pipenv displays its Locking [packages] dependencies... line and hangs. Now, the docs don’t tell you that. The most atrocious example was a local Nikola install that was done in two runs: the first pipenv install Nikola run was interrupted [4] right after it was done installing packages, so the cache had all the necessary wheels in it. The install took 10 minutes and 7 seconds, 9:50 of which were taken by locking dependencies and installing the locked dependencies — so, roughly nine and a half minutes were spent staring at a static screen, with the tool doing something in the background — and Pipenv doesn’t tell you what happens in this phase.

(Updated 2018-07-22: In the pipenv measurements: the first entry is the total time of pipenv executon. The second is the long wait for pipenv to do its “main” job: locking dependencies and installing them. The timing starts when pipenv starts locking dependencies and ends when the prompt appears. The third item is pipenv’s reported installation time. So, pipenv install ⊇ locking/installing ⊇ Pipfile.lock install.)

Task

Action

Measurement method

Environment

Cache

Times in seconds

Attempt 1

Attempt 2

Attempt 3

Average

1

virtualenv

time

Remote

(not applicable)

3.911

4.052

3.914

3.959

2

pip install Nikola

time

Remote

Removed

11.562

11.943

11.773

11.759

3

pip install Nikola

time

Remote

Kept

7.404

7.681

7.569

7.551

4

pipenv install Nikola

time

Remote

Removed

67.536

62.973

71.305

67.271

├─ locking/installing from lockfile

stopwatch

42.6

40.5

39.6

40.9

└─ Pipfile.lock install

pipenv

14

14

13

13.667

5

adding Django to an environment

time

Remote

Kept (only Nikola in cache)

39.576

—

—

39.576

├─ locking/installing from lockfile

stopwatch

32

—

—

32

└─ Pipfile.lock install

pipenv

14

—

—

14

6

adding Django to another environment

time

Remote

Kept (both in cache)

37.978

—

—

37.978

├─ locking/installing from lockfile

stopwatch

30.2

—

—

30.2

└─ Pipfile.lock install

pipenv

14

—

—

14

7

pipenv install Django

time

Remote

Removed

20.612

20.666

20.665

20.648

├─ locking/installing from lockfile

stopwatch

6.6

6.4

6

6.333

└─ Pipfile.lock install

pipenv

1

1

1

1

8

pipenv install Django (new env)

time

Remote

Kept

17.615

—

—

17.615

├─ locking/installing from lockfile

stopwatch

3.5

—

—

3.5

└─ Pipfile.lock install

pipenv

1

—

—

1

9

pipenv install Nikola

time

Remote

Partial

61.507

—

—

61.507

├─ locking/installing from lockfile

stopwatch

38.40

—

—

38.40

└─ Pipfile.lock install

pipenv

14

—

—

14

10

pipenv install Django

time

Local

Removed

73.933

—

—

73.933

├─ locking/installing from lockfile

stopwatch

46

—

—

46

└─ Pipfile.lock install

pipenv

0

—

—

0

11

virtualenv

time

Local

(not applicable)

5.864

—

—

5.864

12

pip install Nikola (cached)

time

Local

Kept

10.951

—

—

10.951

13

pipenv install Nikola

time

Local

Partial, after interruption

607.647

(10m 7s)

607.647

├─ locking/installing from lockfile

stopwatch

590.85

(9m 50s)

590.85

└─ Pipfile.lock install

pipenv

6

6

14

pipenv install

time

Local

Kept

31.399

(L/I: 10.51 s)

31.399

Alternative tools

Python packaging is something with the state of which nobody seems to be satisfied. As such, there are many new contenders for the role of “best new packaging tool”.

Two popular alternatives packaging tools are pip-tools (by Vincent Driessen and Jazzband) and Poetry (by Sébastien Eustace).

Pip-tools: locking and hashing, and that is all

Pip-tools contains two tools. The first one is pip-compile. It locks dependencies in requirements.txt files, and that’s all it does. It allows updating dependencies in the file based on what’s on PyPI. You can optionally add hashes to that file. The second tool is pip-sync. It will synchronize your virtualenv and the requirements file: it will delete packages not in that file, so that you don’t work with stuff not declared in requirements, and will ensure versions match the requirements file. pip-compile takes roughly 10-20 seconds to run in the Nikola repo with a clean pip-tools cache (but with the pip cache intact).

Its speed is fairly reasonable, and it does not try to be the be-all-end-all tool for development. It handles a specific task, does it well, and does not try to handle tasks it should not. Pip-tools lets you work with venvs in any way you like, and it does not require anything specific. Unlike Pipenv and Poetry, you can install it into the virtualenvs that need it, and not system-wide.

Poetry: better, but still not convincing

Poetry is somewhere in between. Its main aim is close to Pipenv, but it also makes it possible to distribute things to PyPI. It tries really hard to hide that it uses Pip behind the scenes. Its README comes with an extensive “What about Pipenv?” section, which I recommend reading — it has a few more examples of bad Pipenv features. Poetry claims to use the standardized (PEP 518) pyproject.toml file to replace the usual lot of files. Unfortunately, the only thing that is standardized is the file name and syntax. Poetry uses custom [tool.poetry] sections, which means that one needs Poetry to fully use the packages created with it, leading to vendor lock-in. There is a build feature to produce a sdist with setup.py and friends.

In February 2020, in a simple poetry add Nikola test, it took about a minute (55.1/50.8/53.6 s) to resolve dependencies (according to Poetry’s own count, Local environment, Poetry cache removed), complete with reassuring output and no quiet lockups. Not as good as pip, but it’s more reasonable than Pipenv. Also, the codebase and its layout are rather convoluted, and the docs are very sparse and lacking. Poetry produces packages instead of just managing dependencies, so it’s generally more useful than Pipenv. That said, I am not convinced by that tool either.

Pip is here to stay!

But in all the talk about new tools, we’re forgetting about the old ones, and they do their job well — so well in fact, that the new tools still need them under the covers.

Pip is fast. It does its job well enough. It lacks support for splitting packages between production and development (as Pipenv and Poetry do). This means that pip freeze and pip install are instant, at the cost of (a) needing two separate environments, or (b) installing development dependencies in production (which should only be a waste of HDD space and nothing more in a well-architected system). But at the same time, pip-tools can help keep the environments separate, as long as you take some time to write separate requirements.in files.

The virtualenv management features can be provided by virtualenvwrapper. That tool’s main advantage is the shell script implementation, which means that workon foo activates the foo virtualenv without spawning a new subshell (an issue with Pipenv and Poetry, that I already covered when describing Pipenv’s operation in the Running scripts (badly) chapter.) An argument often raised by Pipenv proponents is that one does not need to concern itself with creating the virtualenv, and doesn’t need to care where it is. Unfortuntately, many tools require this knowledge from their user, or force a specific location, or require it to be different to the home directory.

And for a reasonable project template with release automation — well, I have my own entry in that category, called (rather unoriginally) the Python Project Template (PyPT).

Yes, setup.py files are not ideal, since they use .py code and a function execution, making access to meta information hard (./setup.py egg_info creates tool-accessible text files). Their main advantage is that they are the only format that is widely supported — pip is the de-facto default Python package manager (which is pre-installed on Windows and Mac), and other tools would require installation/bootstrapping first.

The break-neck pace of Pipenv

A good packaging tool is stable. In other words, it doesn’t change often, and it strives to support existing environments. It wouldn’t be fun to re-download everything on your system, because someone decided that /usr is now called /stuff, and all the files in /usr would become forgotten and not removed. Well, this is what Pipenv did:

Date/Time (UTC)

Event

2017-01-31 22:01

v3.2.14 released. pipenv --three creates ./.venv (eg. ~/git/foo/.venv). Last version with the original behavior of pipenv.

2017-02-01 05:36

v3.3.0 released. pipenv --three creates ~/.local/share/virtualenvs/foo (to be precise, $WORKON_HOME/foo).

2017-02-01 06:10

Issue #178 is reported regarding the behavior change.

2017-02-01 06:18

Kenneth Reitz responds: “no plans for making it configurable.” and closes the issue.

2017-02-02 03:05

Kenneth Reitz responds: “added PIPENV_VENV_IN_PROJECT mode for classic operation. Not released yet.”

2017-02-02 04:29

v3.3.3 released. The default is still uses a “remote” location, but .venv can now be used.

2017-03-02 13:48

v3.5.0 released. The new default path is $WORKON_HOME/foo-HASH, eg. ~/.local/share/virtualenvs/foo-7pl2iuUI.

Over the course of a month, the location of the virtualenv changed twice. If the user didn’t read the changelog and didn’t manually intervene (also of note, the option name was mentioned in the issue and in v3.3.4’s changelog), they would have a stale .venv directory, since the new scheme was adopted for them. And then, after switching to v3.5.0, they would have a stale virtualenv hidden somewhere in their home directory, because pipenv decided to add hashes.

Also, this is not configurable. One cannot disable the hashes in paths, even though users wanted to. It would also help people who want to mix Pipenv and virtualenvwrapper.

Pipenv is a very opinionated tool, and if the dev team changes their mind, the old way is not supported.

Pipenv moves fast and doesn’t care if anything breaks. As an example, between 2018-03-13 13:21 and 2018-03-14 13:44 (a little over 24 hours), Pipenv had 10 releases, ranging from v11.6.2 to v11.7.3. The changelog is rather unhelpful when it comes to informing users what happened in each of the releases.

Extra reading:

Conclusion

  • Pipenv, contrary to popular belief and (now removed) propaganda, is not an officially recommended tool of Python.org. It merely has a tutorial written about it on packaging.python.org (page run by the PyPA).

  • Pipenv solves one use case reasonably well, but fails at many others, because it forces a particular workflow on its users.

  • Pipenv does not handle any parts of packaging (cannot produce sdists and wheels). Users who want to upload to PyPI need to manage a setup.py file manually, alongside and independently of Pipenv.

  • Pipenv produces lockfiles, which are useful for reproducibility, at the cost of installation speed. The speed is a noticeable issue with the tool. pip freeze is good enough for this, even if there are no dependency classes (production vs development) and no hashes (which have minor benefits) [2]

  • Poetry supports the same niche Pipenv does, while also adding the ability to create packages and improving over many gripes of Pipenv. A notable issue is the use of a custom all-encompassing file format, which makes switching tools more difficult (vendor lock-in).

  • Pip, setup.py, and virtualenv — the traditional, tried-and-true tools — are still available, undergoing constant development. Using them can lead to a simpler, better experience. Also of note, tools like virtualenvwrapper can manage virtualenvs better than the aforementioned new Python tools, because it is based on shell scripts (which can modify the enivironment).

  • Since 2018, the packaging scene deteriorated even more. See How to improve Python packaging, or why fourteen tools are at least twelve too many (from January 2023) and Python Packaging, One Year Later: A Look Back at 2023 in Python Packaging (from January 2024).

Other discussion threads: r/Python, Hacker News.