Difference between revisions of "Python deployments"

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== Check Python ==
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Hynek Schlawack
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Check the version of the default Python interpreter:
 
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<code>python --version</code>
 
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List the versions of python available:
 
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<code>ls /usr/bin/python*</code>
 
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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>
 
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<code>update-alternatives --install /usr/bin/python python /usr/bin/python2.7 1</code><br>
 
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<code>update-alternatives --install /usr/bin/python python /usr/bin/python3.6 2</code>
 
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Now we can list the choices:
 
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<code>update-alternatives --list python</code>
 
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And choose one:
 
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<code>update-alternatives --config python</code>
 
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We can also remove a choice if it's no longer an option on the system:
 
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<code>update-alternatives --remove python /usr/bin/python2.7</code>
 
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== Python Virtual Environments ==
 
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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.
 
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<ref>
 
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<source lang="bash">
 
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cd
 
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mkdir environments
 
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cd environments/
 
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pyvenv my_env
 
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source my_env/bin/activate
 
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pip install --upgrade pip
 
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pip install soundscrape
 
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pip install soundscrape --upgrade
 
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soundscrape https://soundcloud.com/pianoman_weddings/coldplay
 
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</source>
 
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</ref>
 
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Hynek Schlawack (from 2013)
 
 
* [https://hynek.me/talks/python-deployments/ Notes]
 
* [https://hynek.me/talks/python-deployments/ Notes]
 
* [https://www.youtube.com/watch?v=RvbDCzroavY Video]
 
* [https://www.youtube.com/watch?v=RvbDCzroavY Video]
  
 
== Python Packaging ==
 
== Python Packaging ==
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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>
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Christoph Haas discusses virtualenv, easy_install, pip, apt/yum
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https://workaround.org/easy-install-debian
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== Basic PIP and Virtual Environments ==
 
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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</code> to help prevent any potential confusion as to which Python interpreter a virtual environment will be based on. '''python3''' is not generic. It represents the '''exact''' version you wish to use in your virtual environment.
 
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As an example, I needed to create a Python Virtual Environment to use the [https://github.com/freephile/meza/issues/63#issuecomment-2020431602 Ansible Playbook Grapher]
 
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<source lang="bash">
 
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python3.11 -m venv myenv
 
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# .. some output ..
 
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source myenv/bin/activate
 
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# maybe upgrade pip
 
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pip install --upgrade pip
 
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# then install your local environment packages
 
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pip install what-i-want
 
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# done using this python?
 
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deactivate
 
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</source>
 
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You only use sudo or elevated permissions when you want to install stuff for the global, system-wide Python installation.
 
  
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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.
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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.
  
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As a bonus, virtualenv does not need elevated permissions.
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== Basic PIP ==
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pip is a fast-moving target and the packaged versions in Debian or Ubuntu are old and buggy.  So, you should get pip from upstream.
  
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* Installing a package is as simple as <code>pip install foo</code>
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* Installing a package is as simple as <code>sudo pip install foo</code>
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* Upgrades are <code>pip install --upgrade foo</code>  
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* Upgrades are <code>sudo pip install --upgrade foo</code>  
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* <code>pip uninstall foo</code> if you want to remove foo
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* <code>sudo pip uninstall foo</code> if you want to remove foo<ref>but you might have to resort to brute force like <code>sudo rm -rf /usr/local/lib/python2.7/dist-packages/dopy*</code> since old pip is buggy.  Or try without sudo.  Or just upgrade pip</ref>
  
 
{{References}}
 
{{References}}

Revision as of 12:25, 28 July 2016

Hynek Schlawack

Python Packaging[edit | edit source]

Christoph Haas discusses virtualenv, easy_install, pip, apt/yum https://workaround.org/easy-install-debian

Stackoverflow says 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.

Basic PIP[edit | edit source]

pip is a fast-moving target and the packaged versions in Debian or Ubuntu are old and buggy. So, you should get pip from upstream.

  • Installing a package is as simple as sudo pip install foo
  • Upgrades are sudo pip install --upgrade foo
  • sudo pip uninstall foo if you want to remove foo[1]

References[edit source]

  1. ↑ but you might have to resort to brute force like sudo rm -rf /usr/local/lib/python2.7/dist-packages/dopy* since old pip is buggy. Or try without sudo. Or just upgrade pip
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