David-OConnor/ pyflow

(0.3.1) 5 months ago

Python

Rust

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About the developer

David-OConnor

908 Stars

37 Forks

MIT License

335 Commits

43 Opened issues

Description

An installation and dependency system for Python

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Pyflow

Name: pyflow
Brand: pyflow
SKU: //David-OConnor/pyflow
Rating: 3.816 (908 reviews)

Simple is better than complex - The Zen of Python

Pyflow streamlines working with Python projects and files. It's an easy-to-use CLI app with a minimalist API. Never worry about having the right version of Python or dependencies.

Example use, including setting up a project and switching Py versions:

If your project's already configured, the only command you need is

pyflow

, or

pyflow myscript.py

; setting up Python and its dependencies are automatic.

Goals: Make using and publishing Python projects as simple as possible. Actively managing Python environments shouldn't be required to use dependencies safely. We're attempting to fix each stumbling block in the Python workflow, so that it's as elegant as the language itself.

You don't need Python or any other tools installed to use Pyflow.

It runs standalone scripts in their own environments with no config, and project functions directly from the CLI.

It implements PEP 582 -- Python local packages directory and Pep 518 (pyproject.toml).

Installation

Windows - Download and run this installer. Or, if you have Scoop installed, run
```
scoop install pyflow
```
.
Ubuntu, or another Os that uses Snap - Run
```
snap install pyflow --classic
```
.
Ubuntu or Debian without Snap - Download and run this deb.
Fedora, CentOs, RedHat, or older versions of SUSE - Download and run this rpm.
A different Linux distro - Download this standalone binary and place it somewhere accessible by the PATH. For example,
```
/usr/bin
```
.
Mac - Run
```
brew install pyflow
```
With Pip - Run
```
pip install pyflow
```
. The linux install using this method is much larger than with the above ones, and it doesn't yet work with Mac. This method will likely not work with Red Hat, CentOs, or Fedora.
- If you have Rust installed - Run
```
cargo install pyflow
```
  .

Quickstart

(Optional) Run
```
pyflow init
```
in an existing project folder, or
```
pyflow new projname
```
to create a new project folder.
```
init
```
imports data from
```
requirements.txt
```
or
```
Pipfile
```
;
```
new
```
creates a folder with the basics.
Run
```
pyflow install requests
```
etc to install packages. Alternatively, edit
```
pyproject.toml
```
directly.
Run
```
pyflow
```
or
```
pyflow myfile.py
```
to run Python.

Quick-and-dirty start for quick-and-dirty scripts

Add the line
```
__requires__ = ['numpy', 'requests']
```
somewhere in your script, where
```
numpy
```
and
```
requests
```
are dependencies.
Optionally add the line
```
__python__ = X.Y.Z
```
, where
```
X.Y.Z
```
is a Python version specification. Without this line, you will be prompted to choose a version when running the script.
Run
```
pyflow script myscript.py
```
, where
```
myscript.py
```
is the name of your script. This will set up an isolated environment for this script, and install dependencies as required. This is a safe way to run one-off Python files that aren't attached to a project, but have dependencies.

Why add another Python manager?

Pipenv

Poetry

, and

Pyenv

address parts of Pyflow's raison d'être, but expose stumbling blocks that may frustrate new users, both when installing and using. Some reasons why this is different:

It behaves consistently regardless of how your system and Python installations are configured.
It automatically manages Python installations and environments. You specify a Python version in
```
pyproject.toml
```
(if omitted, it asks), and it ensures that version is used. If the version's not installed, Pyflow downloads a binary, and uses that. If multiple installations are found for that version, it asks which to use.
```
Pyenv
```
can be used to install Python, but only if your system is configured in a certain way: I don’t think expecting a user’s computer to compile Python is reasonable.
By not using Python to install or run, it remains environment-agnostic. This is important for making setup and use as simple and decision-free as possible. It's common for Python-based CLI tools to not run properly when installed from
```
pip
```
due to the
```
PATH
```
or user directories not being configured in the expected way.
Its dependency resolution and locking is faster due to using a cached database of dependencies, vice downloading and checking each package, or relying on the incomplete data available on the pypi warehouse.
```
Pipenv
```
’s resolution in particular may be prohibitively-slow on weak internet connections.
It keeps dependencies in the project directory, in
```
__pypackages__
```
. This is subtle, but reinforces the idea that there's no hidden state.
It will always use the specified version of Python. This is a notable limitation in
```
Poetry
```
; Poetry may pick the wrong installation (eg Python2 vice Python3), with no obvious way to change it. Poetry allows projects to specify version, but neither selects, nor provides a way to select the right one. If it chooses the wrong one, it will install the wrong environment, and produce a confusing error message. This can be worked around using
```
Pyenv
```
, but this solution isn't documented, and adds friction to the workflow. It may confuse new users, as it occurs by default on popular linux distros like Ubuntu. Additionally,
```
Pyenv's
```
docs are confusing: It's not obvious how to install it, what operating systems it's compatible with, or what additional dependencies are required.
Multiple versions of a dependency can be installed, allowing resolution of conflicting sub-dependencies. (ie: Your package requires
```
Dep A>=1.0
```
and
```
Dep B
```
.
```
Dep B
```
requires Dep
```
A==0.9
```
) There are many cases where
```
Poetry
```
and
```
Pipenv
```
will fail to resolve dependencies. Try it for yourself with a few random dependencies from pypi; there's a good chance you'll hit this problem using
```
Poetry
```
or
```
Pipenv
```
. Limitations: This will not work for some compiled dependencies, and attempting to package something using this will trigger an error.

Perhaps the biggest philosophical difference is that Pyflow abstracts over environments, rather than expecting users to manage them.

My OS comes with Python, and Virtual environments are easy. What's the point of this?

Hopefully we're not replacing one problem with another.

Some people like the virtual-environment workflow - it requires only tools included with Python, and uses few console commands to create, and activate and environments. However, it may be tedious depending on workflow: The commands may be long depending on the path of virtual envs and projects, and it requires modifying the state of the terminal for each project, each time you use it, which you may find inconvenient or inelegant.

I think we can do better. This is especially relevant for new Python users who don't understand venvs, or are unaware of the hazards of working with a system Python.

Pipenv

improves the workflow by automating environment use, and allowing reproducible dependency graphs.

Poetry

improves upon

Pipenv's

API, speed, and dependency resolution, as well as improving the packaging and distributing process by using a consolidating project config. Both are sensitive to the environment they run in, and won't work correctly if it's not as expected.

Conda

addresses these problems elegantly, but maintains a separate repository of binaries from

PyPi

. If all packages you need are available on

Conda

, it may be the best solution. If not, it requires falling back to

Pip

, which means using two separate package managers.

When building and deploying packages, a set of overlapping files are traditionally used:

setup.py

setup.cfg

requirements.txt

and

MANIFEST.in

. We use

pyproject.toml

as the single-source of project info required to build and publish.

A thoroughly biased feature table

These tools have different scopes and purposes:

| Name | Pip + venv | Pipenv | Poetry | pyenv | pythonloc | Conda |this | |------|------------|--------|--------|-------|-----------|-------|-----| | Manages dependencies | ✓ | ✓ | ✓ | | | ✓ | ✓| | Resolves/locks deps | | ✓ | ✓ | | | ✓ | ✓| | Manages Python installations | | | | ✓ | | ✓ | ✓ | | Py-environment-agnostic | | | | ✓ | | ✓ | ✓ | | Included with Python | ✓ | | | | | | | | Stores deps with project | | |✓| | ✓ | | ✓| | Requires changing session state | ✓ | | | ✓ | | | | | Clean build/publish flow | | | ✓ | | | | ✓ | | Supports old Python versions | with

virtualenv

| ✓ | ✓ | ✓ | ✓ | ✓ | | | Isolated envs for scripts | | | | | | | ✓ | | Runs project fns from CLI | | ✓ | ✓ | | | | ✓ |

Use

Optionally, create a
```
pyproject.toml
```
file in your project directory. Otherwise, this file will be created automatically. You may wish to use
```
pyflow new
```
to create a basic project folder (With a .gitignore, source directory etc), or
```
pyflow init
```
to populate info from
```
requirements.txt
```
or
```
Pipfile
```
. See PEP 518 for details.

Example contents: ```toml [tool.pyflow] py_version = "3.7" name = "runcible" version = "0.3.1" authors = ["John Hackworth [email protected]"]

[tool.pyflow.dependencies] numpy = "^1.16.4" diffeqpy = "1.1.0" ``

The

[tool.pyflow]

section is used for metadata. The only required item in it is

py_version

, unless
building and distributing a package. The

[tool.pyflow.dependencies]

section
contains all dependencies, and is an analog to

requirements.txt

. You can specify
developer dependencies in the

[tool.pyflow.dev-dependencies]

section. These
won't be packed or published, but will be installed locally. You can install these
from the cli using the

--dev

flag. Eg:

pyflow install black --dev`

You can specify

extra

dependencies, which will only be installed when passing explicit flags to

pyflow install

, or when included in another project with the appropriate flag enabled. Ie packages requiring this one can enable with

pip install -e

etc.

toml
[tool.pyflow.extras]
test = ["pytest", "nose"]
secure = ["crypto"]

If you'd like to an install a dependency with extras, use syntax like this:

toml
[tool.pyflow.dependencies]
ipython = { version = "^7.7.0", extras = ["qtconsole"] }

To install from a local path instead of

pypi

, use syntax like this: ```toml [tool.pyflow.dependencies]

packagename = { path = "path-to-package"}

numpy = { path = "../numpy" } ```

To install from a

git

repo, use syntax like this:

toml
[tool.pyflow.dependencies]
saturn = { git = "https://github.com/david-oconnor/saturn.git" }  # The trailing `.git` here is optional.

git

dependencies are currently experimental. If you run into problems with them, please submit an issue.

To install a package that includes a

in its name, enclose the name in quotes.

For details on how to specify dependencies in this

Cargo.toml

-inspired semver format, reference this guide.

We also attempt to parse metadata and dependencies from tool.poetry sections of

pyproject.toml

, so there's no need to modify the format if you're using that.

You can specify direct entry points to parts of your program using something like this in

pyproject.toml

toml
[tool.pyflow.scripts]
name = "module:function"

Where you replace

name

function

, and

module

with the name to call your script with, the function you wish to run, and the module it's in respectively. This is similar to specifying scripts in

setup.py

for built packages. The key difference is that functions specified here can be run at any time, without having to build the package. Run with

pyflow name

to do this.

If you run

pyflow package

on on a package using this, the result will work like normal script entry points for someone using the package, regardless of if they're using this tool.

What you can do

Managing dependencies:

```
pyflow install
```
- Install all packages in
```
pyproject.toml
```
, and remove ones not (recursively) specified. If an environment isn't already set up for the version specified in
```
pyproject.toml
```
, sets one up. Note that this command isn't required to sync dependencies; any relevant
```
pyflow
```
command will do so automatically.
```
pyflow install requests
```
- If you specify one or more packages after
```
install
```
, those packages will be added to
```
pyproject.toml
```
and installed. You can use the
```
--dev
```
flag to install dev dependencies. eg:
```
pyflow install black --dev
```
.
```
pyflow install numpy==1.16.4 matplotlib>=3.1
```
- Example with multiple dependencies, and specified versions
```
pyflow uninstall requests
```
- Remove one or more dependencies

Running REPL and Python files in the environment:

```
pyflow
```
- Run a Python REPL
```
pyflow main.py
```
- Run a python file
```
pyflow ipython
```
,
```
pyflow black
```
etc - Run a CLI tool like
```
ipython
```
, or a project function For the former, this must have been installed by a dependency; for the latter, it's specified under
```
[tool.pyflow]
```
,
```
scripts
```
```
pyflow script myscript.py
```
- Run a one-off script, outside a project directory, with per-file package management

Building and publishing:

```
pyflow package
```
- Package for distribution (uses setuptools internally, and builds both source and wheel.)
```
pyflow package --extras "test all"
```
- Package for distribution with extra features enabled, as defined in
```
pyproject.toml
```
```
pyflow publish
```
- Upload to PyPi (Repo specified in
```
pyproject.toml
```
. Uses
```
Twine
```
internally.)

Misc:

```
pyflow list
```
- Display all installed packages and console scripts
```
pyflow new projname
```
- Create a directory containing the basics for a project: a readme, pyproject.toml, .gitignore, and directory for code
```
pyflow init
```
- Create a
```
pyproject.toml
```
file in an existing project directory. Pull info from
```
requirements.text
```
and
```
Pipfile
```
as required.
```
pyflow reset
```
- Remove the environment, and uninstall all packages
```
pyflow clear
```
- Clear the cache, of downloaded dependencies, Python installations, or script- environments; it will ask you which ones you'd like to clear.
```
pyflow -V
```
- Get the current version of this tool
```
pyflow help
```
Get help, including a list of available commands

How installation and locking work

Running

pyflow install

syncs the project's installed dependencies with those specified in

pyproject.toml

. It generates

pyflow.lock

, which on subsequent runs, keeps dependencies each package a fixed version, as long as it continues to meet the constraints specified in

pyproject.toml

. Adding a package name via the CLI, eg

pyflow install matplotlib

simply adds that requirement before proceeding.

pyflow.lock

isn't meant to be edited directly.

Each dependency listed in

pyproject.toml

is checked for a compatible match in

pyflow.lock

If a constraint is met by something in the lock file, the version we'll sync will match that listed in the lock file. If not met, a new entry is added to the lock file, containing the highest version allowed by

pyproject.toml

. Once complete, packages are installed and removed in order to exactly meet those listed in the updated lock file.

This tool downloads and unpacks wheels from

pypi

, or builds wheels from source if none are available. It verifies the integrity of the downloaded file against that listed on

pypi

using

SHA256

, and the exact versions used are stored in a lock file.

When a dependency is removed from

pyproject.toml

, it, and its subdependencies not also required by other packages are removed from the

__pypackages__

folder.

How dependencies are resolved

Compatible versions of dependencies are determined using info from the PyPi Warehouse (available versions, and hash info), and the

pydeps

database. We use

pydeps

, which is built specifically for this project, due to inconsistent dependency information stored on

pypi

. A dependency graph is built using this cached database. We attempt to use the newest compatible version of each package.

If all packages are either only specified once, or specified multiple times with the same newest-compatible version, we're done resolving, and ready to install and sync.

If a package is included more than once with different newest-compatible versions, but one of those newest-compatible is compatible with all requirements, we install that one. If not, we search all versions to find one that's compatible.

If still unable to find a version of a package that satisfies all requirements, we install multiple versions of it as-required, store them in separate directories, and modify their parents' imports as required.

Note that it may be possible to resolve dependencies in cases not listed above, instead of installing multiple versions. Ie we could try different combinations of top-level packages, check for resolutions, then vary children as-required down the hierarchy. We don't do this because it's slow, has no guarantee of success, and involves installing older versions of packages.

Not-yet-implemented

Installing global CLI tools
The lock file is missing some info like hashes
Adding a dependency via the CLI with a specific version constraint, or extras.
Install packages from a local
```
wheel
```
directly. In the meanwhile, you can use a
```
path
```
dependency of the unpacked wheel.
Dealing with multiple-installed-versions of a dependency that uses importlib or dynamic imports
Install Python on Mac

Building and uploading your project to PyPi

In order to build and publish your project, additional info is needed in

pyproject.toml

, that mimics what would be in

setup.py

. Example: ```toml [tool.pyflow] name = "everythingkiller" pyversion = "3.6" version = "0.3.1" authors = ["Fraa Erasmas [email protected]"] description = "Small, but packs a punch!" homepage = "https://everything.math" repository = "https://github.com/raz/everythingkiller" license = "MIT" keywords = ["nanotech", "weapons"] classifiers = [ "Topic :: System :: Hardware", "Topic :: Scientific/Engineering :: Human Machine Interfaces", ] pythonrequires = ">=3.6"

If not included, will default to

test.pypi.org

package_url = "https://upload.pypi.org/legacy/"

[tool.pyflow.scripts]

name = "module:function"

activate = "jeejah:activate"

[tool.pyflow.dependencies] numpy = "^1.16.4" manimlib = "0.3.1" ipython = {version = "^7.7.0", extras=["qtconsole"]}

[tool.pyflow.dev-dependencies] black = "^18.0" ``

package_url

is used to determine which package repository to upload to. If omitted,

Pypi test

is used (

https://test.pypi.org/legacy/`).

Other items you can specify in

[tool.pyflow]

: -

readme

: The readme filename, use this if it's named something other than

README.md

. -

build

: A python script to execute building non-python extensions when running

pyflow package

Building this from source

If you’d like to build from source, download and install Rust, clone the repo, and in the repo directory, run

cargo build --release

Ie on linux or Mac:

bash
curl https://sh.rustup.rs -sSf | sh
git clone https://github.com/david-oconnor/pyflow.git
cd pyflow
cargo build --release

Updating

If installed via
```
Scoop
```
, run
```
scoop update pyflow
```
.
If installed via
```
Snap
```
, run
```
snap refresh pyflow
```
.
If installed via
```
Cargo
```
, run
```
cargo install pyflow --force
```
.
If installed via
```
Pip
```
, run
```
pip install --upgrade pyflow
```
.
If using an installer or deb, run the new version's installer or deb. If manually calling a binary, replace it.

Uninstalling

If installed via
```
Scoop
```
, run
```
scoop uninstall pyflow
```
.
If installed via
```
Snap
```
, run
```
snap remove pyflow
```
.
If installed via
```
Cargo
```
, run
```
cargo uninstall pyflow
```
.
If installed via
```
Pip
```
, run
```
pip uninstall pyflow
```
.
If installed via Windows installer, run the Installer again and select
```
Remove
```
when asked, or use
```
Apps & features
```
.
If installed via a
```
deb
```
, use the
```
Software Center
```
.
If manually calling a binary, remove it.

Contributing

If you notice unexpected behavior or missing features, please post an issue, or submit a PR. If you see unexpected behavior, it's probably a bug! Post an issue listing the dependencies that did not install correctly.

Why not to use this

It's adding another tool to an already complex field.
Most of the features here are already provided by a range of existing packages, like the ones in the table above.
The field of contributors is expected to be small, since it's written in a different language.
Dependency managers like Pipenv and Poetry work well enough for many cases, have dedicated dev teams, and large userbases.
```
Conda
```
in particular handles many things this does quite well.

Dependency cache repo:

Github Example API calls:
```
https://pydeps.herokuapp.com/requests
```
,
```
https://pydeps.herokuapp.com/requests/2.21.0
```
. This pulls all top-level dependencies for the
```
requests
```
package, and the dependencies for version
```
2.21.0
```
respectively. There is also a
```
POST
```
API for pulling info on specified versions. The first time this command is run for a package/version combo, it may be slow. Subsequent calls, by anyone, should be fast. This is due to having to download and install each package on the server to properly determine dependencies, due to unreliable information on the
```
pypi warehouse
```
.

Python binary sources:

Repo binaries are downloaded from

Windows: Python official Visual Studio package, by Steve Dower.
Newer linux distros: Built on Ubuntu 18.04, using standard procedures.
Older linux distros: Built on CentOS 7, using standard procedures.

Gotchas

Make sure
```
__pypackages__
```
is in your
```
.gitignore
```
file.
You may need to set up IDEs to find packages in
```
__pypackages__
```
. If using PyCharm:
```
Settings
```
→
```
Project
```
→
```
Project Interpreter
```
→
```
⚙
```
→
```
Show All...
```
→ (Select the interpreter, ie
```
(projname)/__pypackages__/3.x/.venv/bin/python
```
on Linux/Mac, or
```
(projname)/__pypackages__/3.x/Scripts/python
```
on Windows) → Click the folder-tree icon at the bottom of the pop-out window → Click the
```
+
```
icon at the bottom of the new pop-out window → Navigate to and select
```
(projname)/__pypackages__/3.x/lib
```

If using VsCode:

Settings

→ search

python extra paths

→

Edit in settings.json

→ Add or modify the line:

"python.autoComplete.extraPaths": ["(projname)/__pypackages__/3.7/lib"]