Ian Wienand c9b4b01187 Add guidelines on variable naming

This captures some discussion over the scoping of variable names
during some recent role development.  It tries to provide some
guidelines to prefixing of global variable names in roles and
"module-like" roles.

Since "deprecation.rst" is now holding a few different things, it
makes more sense as "policy.rst".

Reorganise to be nested in one more level, and add a contents section
to help find sections easier.

Change-Id: I0d551eefd33744ffa23418d0780769a7e52fe9cf

2018-08-31 09:28:34 +10:00

2.6 KiB

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Policy

Below are some guidelines for developers contributing to zuul-jobs.

Deprecation Policy

Because zuul-jobs is intended for wide use by any Zuul, we try to take care when making backwards incompatible changes.

If we need to do so, we will send a notice to the zuul-announce mailing list describing the change and indicating when it will be merged. We will usually wait at least two weeks between sending the announcement and merging the change.

If the change affects your jobs, and you are unable to adjust to it within the timeframe, please let us know with a message to the zuul-discuss mailing list -- we may be able to adjust the timeframe. Otherwise, you may wish to temporarily switch to a local fork of zuul-jobs (or stop updating it if you already have).

New Zuul Features

When a new feature is available in Zuul, the jobs in zuul-jobs may not be able to immediately take advantage of it. We need to allow time for folks to upgrade their Zuul installations so they will be compatible with the change. In these cases, we will wait four weeks after the first Zuul release with the required feature before merging a change to zuul-jobs which uses it.

Deprecated Zuul Features

Before deprecating a feature in Zuul which is used by zuul-jobs, the usage of the feature must be removed from zuul-jobs according to the deprecation policy described above.

Python Version Policy

zuul-jobs targets Python 2.7 onwards and Python 3.5 onwards (note this differs slightly from Ansible upstream, where the policy is 2.6 onwards unless libraries depend on newer features. zuul-jobs does not support Python 2.6).

Library code should be written to be compatible with both. There are some tips on this in Ansible and Python 3.

Role Variable Naming Policy

Variables referenced by roles from global scope (often intended to be set via host_vars and group_vars, but also set during role inclusion) must be namespaced by prepending their role-name to the variable. Thus example-role would have variables with names such as example_role_variable; e.g.

tasks:
  - name: Call "example" role
    include_role:
      name: example-role
    vars:
      example_role_variable: 'something'

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