Python deployments: Difference between revisions

Revision as of 07:40, 7 October 2020

Check Python

Check the version of the default Python interpreter: python --version

List the versions of python available: ls /usr/bin/python*

Use update-alternatives to setup system-wide ability to choose Python interpreter. The one with the higher priority number will become the default.
update-alternatives --install /usr/bin/python python /usr/bin/python2.7 1
update-alternatives --install /usr/bin/python python /usr/bin/python3.6 2

Now we can list the choices: update-alternatives --list python

And choose one: update-alternatives --config python

We can also remove a choice if it's no longer an option on the system: update-alternatives --remove python /usr/bin/python2.7

Python Virtual Environments

See Digital Ocean's quick guide to setting up a local Python programming environment, including virtual environments, which is what I did for SoundScrape Btw, SoundScrape is a neat tool to download sound files from SoundCloud. ^[1]

Hynek Schlawack (from 2013)

Notes
Video

Python Packaging

In the old days (2015) there were still debates about how to package Python and install stuff. Now, it's settled. Use pip. Easy_install is dead. See the docs. Also note that venv is the successor to virtualenv

Basic PIP and Virtual Environments

Do NOT (normally) use sudo with pip. Use a virtual environment. As of Python 3.4, the command is now called pyvenv or simply venv. As of Python 3.6 pyvenv is deprecated in favor of using python3 -m venv</cod> to help prevent any potential confusion as to which Python interpreter a vritual environment will be based on.

$ python3 -m venv myenv
.. some output ..
$ source myenv/bin/activate
(myenv) $ pip install what-i-want
# done using this python?
deactivate

You only use sudo or elevated permissions when you want to install stuff for the global, system-wide Python installation.
It is best to use a virtual environment which isolates packages for you. That way you can play around without polluting the global python install.
As a bonus, virtualenv does not need elevated permissions.

Installing a package is as simple as pip install foo
Upgrades are pip install --upgrade foo
pip uninstall foo if you want to remove foo

References


↑ 
cd
mkdir environments
cd environments/
pyvenv my_env
source my_env/bin/activate
pip install --upgrade pip
pip install soundscrape
pip install soundscrape --upgrade
soundscrape https://soundcloud.com/pianoman_weddings/coldplay

[1] 
cd mkdir environments cd environments/ pyvenv my_env source my_env/bin/activate pip install --upgrade pip pip install soundscrape pip install soundscrape --upgrade soundscrape https://soundcloud.com/pianoman_weddings/coldplay

[1]

@@ Line 1: / Line 1: @@
-Hynek Schlawack
+== Check Python ==
+Check the version of the default Python interpreter:
+<code>python --version</code>
+List the versions of python available:
+<code>ls /usr/bin/python*</code>
+Use <code>update-alternatives</code> to setup system-wide ability to choose Python interpreter.  The one with the '''higher''' priority number will become the default.<br>
+<code>update-alternatives --install /usr/bin/python python /usr/bin/python2.7 1</code><br>
+<code>update-alternatives --install /usr/bin/python python /usr/bin/python3.6 2</code>
+Now we can list the choices:
+<code>update-alternatives --list python</code>
+And choose one:
+<code>update-alternatives --config python</code>
+We can also remove a choice if it's no longer an option on the system:
+<code>update-alternatives --remove python /usr/bin/python2.7</code>
+== Python Virtual Environments ==
+See Digital Ocean's quick guide to [https://www.digitalocean.com/community/tutorials/how-to-install-python-3-and-set-up-a-local-programming-environment-on-ubuntu-16-04 setting up a local Python programming environment], including [https://virtualenv.pypa.io/en/stable/ virtual environments], which is what I did for [https://github.com/Miserlou/SoundScrape SoundScrape]  Btw, SoundScrape is a neat tool to download sound files from SoundCloud.
+<ref>
+<source lang="bash">
+cd
+mkdir environments
+cd environments/
+pyvenv my_env
+source my_env/bin/activate
+pip install --upgrade pip
+pip install soundscrape
+pip install soundscrape --upgrade
+soundscrape https://soundcloud.com/pianoman_weddings/coldplay
+</source>
+</ref>
+Hynek Schlawack (from 2013)
 * [https://hynek.me/talks/python-deployments/ Notes]
 * [https://www.youtube.com/watch?v=RvbDCzroavY Video]
 == Python Packaging ==
-Christoph Haas discusses virtualenv, easy_install, pip, apt/yum
+In the old days (2015) there were still debates about how to package Python and install stuff.  Now, it's settled. Use pip.  Easy_install is dead. See the [https://docs.python.org/3/installing/index.html docs]. Also note that <code>venv</code> is the successor to <code>virtualenv</code>
-https://workaround.org/easy-install-debian
+== Basic PIP and Virtual Environments ==
+Do NOT (normally) use sudo with pip. Use a virtual environment. As of Python 3.4, the command is now called <code>pyvenv</code> or simply <code>venv</code>.  As of Python 3.6 <code>pyvenv</code> is '''deprecated''' in favor of using <code>python3 -m venv</cod> to help prevent any potential confusion as to which Python interpreter a vritual environment will be based on.
+<source lang="bash">
+$ python3 -m venv myenv
+.. some output ..
+$ source myenv/bin/activate
+(myenv) $ pip install what-i-want
+# done using this python?
+deactivate
+</source>
+You only use sudo or elevated permissions when you want to install stuff for the global, system-wide Python installation.
+It is best to use a virtual environment which isolates packages for you. That way you can play around without polluting the global python install.
+As a bonus, virtualenv does not need elevated permissions.
+* Installing a package is as simple as <code>pip install foo</code>
+* Upgrades are <code>pip install --upgrade foo</code>
+* <code>pip uninstall foo</code> if you want to remove foo
-Stackoverflow says [http://stackoverflow.com/questions/3220404/why-use-pip-over-easy-install/  use pip over easy_install], but things have been changing over the past few years, so the future/best practice may require a bit more digging.
+{{References}}
 [[Category:Python]]