Avoid loading/rendering in Rails if SKIP_CONSULT is set

[aharpervc]

In certain situations, Consult might be loaded by Rails but you don't want it to process templates. For example, from a Rake task that doesn't load the Rails environment. To support those scenarios, you can run the task (etc) with SKIP_CONSULT=true and it won't do anything.

I don't think we can do an automated test in this repo for this feature, since otherwise we'd need a dummy Rails app. Adding that might be a good idea for the future, though.

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Question: Is there a better way to do this?

[aharpervc]

It's a Rails-ism to do .present? (eg), but that seems worse than checking for a truthy value 🤔

[sixfeetover]

There's no functional difference, but I wonder about blocking the auto-load vs short circuiting the method. in other words, doing this:

require 'consult/rails/engine' if defined?(Rails) && ENV['SKIP_CONSULT'].blank?

https://github.com/veracross/consult/blob/master/lib/consult.rb#L103

[aharpervc]

Good idea. Something I was considering is if we'll ever want to get between load and render. I was almost going to do SKIP_CONSULT_RENDER, but in my particular case I also want to skip loading since that'd access vault/consul in a way that isn't useful for my project. So the "skip" instruction ended up one line earlier and one word fewer.

Here's a test question to decide between the current approach and your suggestion... can we imagine any scenario where loading the Railtie integration is useful, but we also don't want to load/render? If yes, then we should keep my approach. If no, then I think yours is better. (I currently can't think of any reason we'd want to load the Railtie if we aren't going to do anything).

[bvogelzang]

I don't necessarily think this would be better and this seems handy enough in other situations but here's an alternative for your acute problem:

You don't necessarily have to load Rails at all to run your rake task. Call the rake tasks with bundle exec rake --rakefile lib/tasks/build.rake namespace:task_name.... This will avoid the need for extra environment variables and reduce the time it takes for the task(s) to run.

You are checking the rails environment but that can be passed into the rake task as a separate argument or could be read from the environment instead.

[aharpervc]

I'd probably still need something from Consult here for things like bundle exec rails dev:cache though right?

[sixfeetover]

I also want to skip loading since that'd access vault/consul in a way that isn't useful for my project

I could be wrong but I think access is JIT, so if templates aren't rendered no Vault/Consul access will be attempted.

can we imagine any scenario where loading the Railtie integration is useful, but we also don't want to load/render

Not that I can think of off the top of my head.

[aharpervc]

I also want to skip loading since that'd access vault/consul in a way that isn't useful for my project

I could be wrong but I think access is JIT, so if templates aren't rendered no Vault/Consul access will be attempted.

The load method will also call these "configure" methods, which I assume are allowed to contact their respective services:

consult/lib/consult.rb

Lines 42 to 43 in 4a90ccf

	configure_consul
	configure_vault

can we imagine any scenario where loading the Railtie integration is useful, but we also don't want to load/render

Not that I can think of off the top of my head.

Great, I'll redo this PR with your suggestion instead.

[ronnietaylor]

Seems reasonable. LGTM