Difference between revisions of "Python deployments"

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== 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.  
 
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>
 
<ref>
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== Basic PIP and Virtual Environments ==
 
== 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</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.
+
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.
 
 
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]
 
 
<source lang="bash">
 
<source lang="bash">
python3.11 -m venv myenv
+
$ python3 -m venv myenv
# .. some output ..
+
.. some output ..
source myenv/bin/activate
+
$ source myenv/bin/activate
# maybe upgrade pip
+
(myenv) $ pip install what-i-want
pip install --upgrade pip
 
# then install your local environment packages
 
pip install what-i-want
 
 
# done using this python?
 
# done using this python?
 
deactivate
 
deactivate
 
</source>
 
</source>
 
 
You only use sudo or elevated permissions when you want to install stuff for the global, system-wide Python installation.
 
You only use sudo or elevated permissions when you want to install stuff for the global, system-wide Python installation.
  

Revision as of 10:27, 2 March 2017

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)

Python Packaging[edit | edit source]

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[edit | edit source]

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[edit source]

  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