fades, a FAst DEpendencies for Scripts, is a system that automatically handles the virtualenvs in the simple cases normally found when writing scripts or simple programs.
fades will automagically create a new virtualenv (or reuse a previous created one), installing the necessary dependencies, and execute your script inside that virtualenv, with the only requirement of executing the script with fades and also marking the required dependencies.
The first non-option parameter (if any) would be then the child program to execute, and any other parameters after that are passed as is to that child script.
fades can also be executed without passing a child script to execute:
in this mode it will open a Python interactive interpreter inside the
created/reused virtualenv (taking dependencies from --dependency
or
--requirement
options).
When you write an script, you have to take two special measures:
- need to execute it with fades (not python)
- need to mark those dependencies
At the moment you execute the script, fades will search a virtualenv with the marked dependencies, if it doesn't exists fades will create it, and execute the script in that environment.
You can always call your script directly with fades:
fades myscript.py
However, for you to not forget about fades and to not execute it directly with python, it's better if you put at the beggining of the script the indication for the operating system that it should be executed with fades...
#!/usr/bin/fades
...and also set the executable bit in the script:
chmod +x yourscript.py
The procedure to mark a module imported by the script as a dependency to be installed by fades is by using a comment.
This comment will normally be in the same line of the import (recommended, less confusing and less error prone in the future), but it also can be in the previous one.
The simplest comment is like:
import somemodule # fades.pypi from somepackage import othermodule # fades.pypi
The fades.pypi
is mandatory, it may allow more options in the future.
With that comment, fades will install automatically in the virtualenv the
somemodule
or somepackage
from PyPI.
Also, you can indicate a particular version condition, examples:
import somemodule # fades.pypi == 3 import somemodule # fades.pypi >= 2.1 import somemodule # fades.pypi >=2.1,<2.8,!=2.6.5
Sometimes, the project itself doesn't match the name of the module; in these cases you can specify the project name (optionally, before the version):
import bs4 # fades.pypi beautifulsoup4 import bs4 # fades.pypi beautifulsoup4 == 4.2
Apart of marking the imports in the source file, there are other ways to tell fades which dependencies to install in the virtualenv.
One way is through command line, passing the --dependency
parameter.
This option can be specified multiple times (once per dependency), and
each time the format is repository::dependency
. The dependency may
have versions specifications, and the repository is optional (defaults
to 'pypi').
Other way is to specify the dependencies in a text file, one dependency
per line, with each line having the format previously described for
the --dependency
parameter. This file is then indicated to fades
through the --requirement
parameter.
In case of multiple definitions of the same dependency, command line overrides everything else, and requirements file overrides what is specified in the source code.
You can influence several details of all the virtualenv related process.
The most important detail is which version of Python will be used in the virtualenv. Of course, the corresponding version of Python needs to be installed in your system, but you can control exactly which one to use.
No matter which way you're executing the script (see above), you can
pass a -p
or --python
argument, indicating the Python version to
be used just with the number (2.7
), the whole name (python2.7
) or
the whole path (/usr/bin/python2.7
).
Other detail is the verbosity of fades when telling what is doing. By default, fades only will use stderr to tell if a virtualenv is being created, and to let the user know that is doing an operation that requires an active network connection (e.g. installing a new dependency).
If you call fades with -v
or --verbose
, it will send all internal
debugging lines to stderr, which may be very useful if any problem arises.
On the other hand if you pass the -q
or --quiet
parameter, fades
will not show anything (unless it has a real problem), so the original
script stderr is not polluted at all.
Sometimes, you want to run a script provided by one of the dependencies
installed into the virtualenv. fades supports this via the -x
(
or --exec
argument).
If you want to use IPython shell you need to call fades with -i
or
--ipython
option. This option will add IPython as a dependency to fades
and it will launch this shell instead of the python one.
fades foo.py --bar
Executes foo.py
under fades, passing the --bar
parameter to the child program, in a virtualenv with the dependencies indicated in the source code.
fades -v foo.py
Executes foo.py
under fades, showing all the fades messages (verbose mode).
fades -d dependency1 -d dependency2>3.2 foo.py --bar
Executes foo.py
under fades (passing the --bar
parameter to it), in a virtualenv with the dependencies indicated in the source code and also dependency1
and dependency2
(any version > 3.2).
fades -d dependency1
Executes the Python interactive interpreter in a virtualenv with dependency1
installed.
fades -r requirements.txt
Executes the Python interactive interpreter in a virtualenv after installing there all dependencies taken from the requirements.txt
file.
fades -d django -x django-admin.py startproject foo
Uses the django-admin.py
script to start a new project named foo
, without having to have django previously installed.
Several instructions to install fades in different systems.
Fades depends on python-xdg
package. This package should be installed on
any GNU/Linux OS wiht a freedesktop.org GUI. However it is an
optional dependency.
You can install it in Ubuntu/Debian with:
apt-get install python-xdg
And on Archlinux with:
pacman -S python-xdg
Fades also needs the virtualenv <https://virtualenv.pypa.io/en/latest/> package to support different Python versions for child execution. (see --python argument.)
It also depends on the pkg_resources
package, that comes in with
setuptools
. Note I didn't find any system where that is not
already included (it's even there in a clean virtualenv).
You have a .deb. Download it and install doing:
sudo dpkg -i fades-latest.deb
We have an AUR package. If you are a yaourt user you can install fades with a simple:
yaourt -S fades
pip3 install fades
Finally you can always get the multiplatform tarball and install it in the old fashion way:
wget http://taniquetil.com.ar/fades/fades-latest.tar.gz tar -xf fades-latest.tar.gz cd fades-* sudo ./setup.py install
Yes! Branch the project and use the executable:
git clone https://github.com/PyAr/fades.git cd fades bin/fades your_script.py
You can ask any question or send any recommendation or request to the mailing list.
Also, you can open an issue here (please do if you find any problem!).
Thanks in advance for your time.
See here for detailed instructions about how to setup everything and develop fades.