Consider whether we should introduce a .env file to setup logging

[antonymilne]

Note. In theory an implementation of this is non-breaking, so could be done at any time. But I think it will be confusing if done before #2426, which is 0.19.0.

Following #2426, a user needs to manually set KEDRO_LOGGING_CONFIG in order for conf/logging.yml to be used. We should consider whether kedro should have a system to automatically set this environment variable. Such a system would be:

• project template includes a new .env file that defines KEDRO_LOGGING_CONFIG=conf/logging.yml
• kedro uses something like dotenv to load this file automatically at the beginning of the kedro process
• load_dotenv() would go at top of framework/project/__init__.py (must be before LOGGING is defined)

This ticket is not to implement the above but to consider whether we actually want to make this change.

Pros:

• conf/logging.yml will be used automatically, no need to set the environment variable yourself (assuming we want to leave file-based logging as opt-out rather than opt-in). Hence there's not an unused file sitting in the template
• file-based logging therefore enabled by default as it is now
• INFO log messages from your project still get shown without needing to handle the complication Consider removing support for project-side logging.yml #2281 on the framework side

Cons:

• an extra file in the template just to set a single environment variable that's used for logging
• possible confusion with environment variables used in run environments

Pro or con depending on your opinion:

• people could use the file to set other environment variables

Overall my opinion would be that we should make this change, mainly for the reason of still seeing INFO log messages from your project.

[antonymilne]

Following discussion in tech design on 12 April we are shelving this idea. See #2281 for more information.