[CASSANDRA-15659] Better support of Python 3 for cqlsh

• Type: Task
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 4.0-beta1, 4.0
• Component/s: Tool/cqlsh
• Labels: pull-request-available
• Change Category: Operability
• Complexity: Normal
• Platform: All

Source Control Link

https://github.com/apache/cassandra/commit/c05443c0980cb51720ba0503f26f084c1538729c

Test and Documentation Plan

https://github.com/apache/cassandra/pull/505

• Assignee: Eduard Tudenhoefner
• Reporter: Stefan Miklosovic

Authors

Eduard Tudenhoefner

Reviewers

Michael Semb Wever

• Created: 24/Mar/20 19:04
• Updated: 15/May/20 08:54
• Resolved: 14/Apr/20 19:02

Description

From mailing list:

https://lists.apache.org/thread.html/r377099b632c62b641e4feef5b738084fc5369b0c7157fae867853597%40%3Cdev.cassandra.apache.org%3E

 

As of today (24/3/2020) and current trunk, there is Python 3.6 supported (1) but there is not any 3.6 version ootb in Debian for example. E.g. Buster has Python 3.7 and other (recent) releases have version 2.7. This means that if one wants to use Python 3 in Debian, he has to use 3.6 but it is not in the repository so he has to download / compile / install it on his own.

There should be some sane Python 3 version supported which is as well present in Debian repository (or requirement to run with 3.6 should be relaxed) .

(1) https://github.com/apache/cassandra/blob/bf9a1d487b9ba469e8d740cf7d1cd419535a7e79/bin/cqlsh#L57-L65

Summary of work that was done:

I relaxed the requirement of cqlsh only working with Python 2.7 & 3.6 by allowing Python 3.6+.
Note that I left the constraint for Python 3.6 being the minimum Python3 version.
As ptbannister pointed out, we could remove the Python 3.6 min version once we remove Python 2.7 support, as otherwise testing with lots of different Python versions will get costly.

2 Dockerfiles were added in pylib for minimal local testing of cqlsh starting up with Python 3.7 & 3.8 and that both revealed
CASSANDRA-15572 and CASSANDRA-15573.
CASSANDRA-15572 was fixed here as it was a one-liner. And I'm going to tackle CASSANDRA-15573 later.

Python 3.8 testing was added to the CircleCI config so that we can actually see what else breaks with newer Python versions.

A new Docker images with Ubuntu 19.10 was required for testing (https://github.com/apache/cassandra-builds/pull/17). This docker image sets up Python 2.7/3.6/3.7/3.8 with their respective virtual environments, which are then being used by the CircleCI yaml.

The image spod/cassandra-testing-ubuntu1810-java11-w-dependencies:20190306 couldn't be updated unfortunately because it can't be built anymore, due to Ubuntu 18.10 being EOL.

Issue Links

• relates to: CASSANDRA-10190 Python 3 support for cqlsh
• relates to: CASSANDRA-15710 DOC - Add cqlsh Python 3 support in NEWS.txt and tools section of website
• relates to: CASSANDRA-15586 4.0 quality testing: Cluster Setup and Maintenance
• links to: GitHub Pull Request #505