Can we use dashes in yml syntax for the config.yml?

[merelcht]

Introduction

#1485

Problem

Currently, there are 2 ways to provide argument to kedro run CLI.

1. Using the CLI argument kedro run --from-nodes=some_node
2. Using the --config argument and define the arguments in a YAML file. kedro run --config=config.yml

# config.yml
run:
  from_nodes: some_node # Notice this is underscore instead of a dash

Task

Ideally the YAML config should use the same arguments as the CLI, i.e. using the dash instead of the underscore. Investigate if it's possible to use dashes in config.yml. The click context handles some of this logic, and so we need to find out if it is possible to use dash in yaml or not. If it is possible, then we'll implement it, but that would be a breaking change.

[merelcht]

This doesn't seem to be possible because of the way click parses parameters.

I haven't been able to fully trace how the config file gets read and parsed, because the click code is super hard to follow and debugging doesn't really work.
But what I've figured out is that when you pass config in yaml and specify from_nodes, this gets filled in as the value in: https://github.com/kedro-org/kedro/blob/main/kedro/framework/cli/project.py#L386. In python you can't name arguments with a dash like "from-nodes" and so if you provide it like that in config.yml, click can't map the value to the python argument.

This part in the click docs talks a bit about naming of paramters: https://click.palletsprojects.com/en/8.1.x/parameters/#parameter-names and they mention "If a name is not prefixed, it is used as the Python argument name and not parsed as an option name."