Allow config option to disable ERB in YAML

[kmcphillips]

Problem

There is currently no way to disable ERB evaluation in YAML files at load time.

This is an issue if the config file has a string that contains ERB to be evaluated later, or something that looks like ERB. It simply raises an error (such as SyntaxError or RuntimeError) at application load time.

Solution

Add the Config.evaluate_erb_in_yaml option, and use it to conditionally evaluate ERB or simply pass the string through.

This is fully backwards compatible as the value defaults to true.

[cjlarose]

Thanks for your contribution! This is great!

I added a suggestion to make it a little nicer if you're up to it. Otherwise, I'm happy to merge as-is and leave the suggestion for future work.

[cjlarose]

Minor suggestion that would be really nice: give users the option to opt into- or out of this behavior on a per-file basis if they're using the YAMLSource API directly. For example,

Config.add_source!(Config::Sources::YAMLSource.new(path1)) # defaults to global Config.evaluate_erb_in_yaml
Config.add_source!(Config::Sources::YAMLSource.new(path1, evaluate_erb: false)) # overrides global setting
Config.add_source!(Config::Sources::YAMLSource.new(path1, evaluate_erb: true)) # overrides global setting

That way it's not all-or-nothing. We do something similar for EnvSource here: configuration is derived from the global values if left unspecified, but can always be overridden.

config/lib/config/sources/env_source.rb

Lines 10 to 14 in 618c839

	def initialize(env,
	prefix: Config.env_prefix || Config.const_name,
	separator: Config.env_separator,
	converter: Config.env_converter,
	parse_values: Config.env_parse_values)

[kmcphillips]

Oh neat. Ok I'll spend some time with this. Feedback makes sense.

[kmcphillips]

I went back and forth on the config name. evaluate_erb is simpler, but then I realized that it only applies to YAML source, so I set it to evaluate_erb_in_yaml. Thoughts?

[kmcphillips]

Or I guess a third option is evaluate_erb in the YAMLSource class, and evaluate_erb_in_yaml in the global config.

[kmcphillips]

Ready for another review.

[cjlarose]

Or I guess a third option is evaluate_erb in the YAMLSource class, and evaluate_erb_in_yaml in the global config.

I like this best and it looks like this is what you went with.

Code looks great! Thanks for making the changes. I'll do some local testing here in the next couple of days, merge, and publish a new version.

[kmcphillips]

Ok! Let me know if you want changes. I'm happy with it I think, but every codebase is different.

Thanks for accepting the contribution.

[cjlarose]

Awesome work!

[kmcphillips]

Nice! Thanks!

[cjlarose]

Published in version 3.1.0!