[GitHub] [airflow] potiuk opened a new pull request #6060: [AIRFLOW-5437] Better python version detection/explanation.

[GitBox <gi...@apache.org>]

potiuk opened a new pull request #6060: [AIRFLOW-5437] Better python version detection/explanation.
URL: https://github.com/apache/airflow/pull/6060
 
 
   We have fairly complex python version detection in our CI scripts.
   
   They have to handle several cases:
   
   1) Running builds on DockerHub (we cannot pass different environment
      variables there, so we detect python version based on the image
      name being build (airflow:master-python3.7 -> PYTHON_VERSION=3.7)
   
   2) Running builds on Travis CI. We use python version determined
      from default python3 version available on the path. This way we
      do not have to specify PYTHON_VERSION separately in each job,
      we just specify which host python version is used for that job.
      This makes a nice UI experience where you see python version in
      Travis UI.
   
   3) Running builds locally via scripts where we can pass PYTHON_VERSION
      as environment variable.
   
   4) Running builds locally for the first time with Breeze. By default
      we determine the version based on default python3 version we have
      in the host system (3.5, 3.6 or 3.7) and we use this one.
   
   5) Selecting python version with Breeze's --python switch. This will
      override python version but it will also store the last used version
      of python in .build directory so that it is automatically used next
      time.
   
   This change adds necessary explanations to the code that works for
   all the cases and fixes some of the edge-cases we had. It also
   extracts the code to common directory.
   
   Make sure you have checked _all_ steps below.
   
   ### Jira
   
   - [ ] My PR addresses the following [Airflow Jira](https://issues.apache.org/jira/browse/AIRFLOW/) issues and references them in the PR title. For example, "\[AIRFLOW-XXX\] My Airflow PR"
     - https://issues.apache.org/jira/browse/AIRFLOW-XXX
     - In case you are fixing a typo in the documentation you can prepend your commit with \[AIRFLOW-XXX\], code changes always need a Jira issue.
     - In case you are proposing a fundamental code change, you need to create an Airflow Improvement Proposal ([AIP](https://cwiki.apache.org/confluence/display/AIRFLOW/Airflow+Improvements+Proposals)).
     - In case you are adding a dependency, check if the license complies with the [ASF 3rd Party License Policy](https://www.apache.org/legal/resolved.html#category-x).
   
   ### Description
   
   - [ ] Here are some details about my PR, including screenshots of any UI changes:
   
   ### Tests
   
   - [ ] My PR adds the following unit tests __OR__ does not need testing for this extremely good reason:
   
   ### Commits
   
   - [ ] My commits all reference Jira issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "[How to write a good git commit message](http://chris.beams.io/posts/git-commit/)":
     1. Subject is separated from body by a blank line
     1. Subject is limited to 50 characters (not including Jira issue reference)
     1. Subject does not end with a period
     1. Subject uses the imperative mood ("add", not "adding")
     1. Body wraps at 72 characters
     1. Body explains "what" and "why", not "how"
   
   ### Documentation
   
   - [ ] In case of new functionality, my PR adds documentation that describes how to use it.
     - All the public functions and the classes in the PR contain docstrings that explain what it does
     - If you implement backwards incompatible changes, please leave a note in the [Updating.md](https://github.com/apache/airflow/blob/master/UPDATING.md) so we can assign it to a appropriate release
   

----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
 
For queries about this service, please contact Infrastructure at:
users@infra.apache.org


With regards,
Apache Git Services