Add support for SPRING_QUIET environment variable.

[thewoolleyman]

Adds support for enabling quiet mode via SPRING_QUIET environment variable.

This is useful in situations where you don't want to put Spring.quiet = true in ~/.spring.rb or your app's config/spring.rb, but want to enable quiet mode on a case-by-case basis.

See more details in the doc updates in this PR.

Closes #467

[thewoolleyman]

I just noticed that @bobf already had a PR to implement this in #577

However, I'm leaving this one open, because:

1. It has more extensive docs
2. It short-circuits in the config reader method via ||= instead of ||, allowing it to be set back to false even after spring starts, if this is necessary.

If this PR is merged, #577 can be closed as a duplicate.

[thewoolleyman]

@rafaelfranca , could we get please some attention on this one to get it merged? It will close out the following:

• Add support for SPRING_QUIET environment variable. #674
• Set quiet mode from environment #577
• Spring stderr output causing warnings in other apps #467

Thanks! 🙏

[bobf]

Glad to see some movement on this. Please feel free to close my PR once this one is closed, or if this one ends up getting stalled somehow then I'm happy to merge the changes into my PR and make any adjustments needed.

[thewoolleyman]

Hi @tenderlove 👋! any chance you or some other committer could help get some attention to getting this merged? Thanks!

[nvasilevski]

It short-circuits in the config reader method via ||= instead of ||, allowing it to be set back to false even after spring starts, if this is necessary.

Correct me if I'm wrong, but at first glance it looks like that it won't be possible to set it back to false after setting it to true once, like:

class DummySpring
  class << self
    attr_writer :quiet

    def quiet
      @quiet ||= ENV.key?('SPRING_QUIET') 
    end
  end
end

ENV["SPRING_QUIET"] = "lol"
DummySpring.quiet # => true
DummySpring.quiet = false
DummySpring.quiet # => still true because `ENV.key?('SPRING_QUIET') ` gets checked again as long as `@quiet` is falsey

[thewoolleyman]

@nvasilevski That's a good point. You could set it back to false via the attr_writer, but not via the ENV var.

But I guess I assumed that you wouldn't try to use the ENV var to change it while an app is executing - if you want to do that, just use the attr_writer.

In other words, the ENV var is only needed when you don't have access to modify the code or config at all, but still want to turn quiet mode on,

This is also explained by the new documentation:

You can also set the initial state of the quiet configuration option to true
by setting the SPRING_QUIET environment variable before executing Spring.

Note it says "initial state" and "...before executing Spring".

So, I guess I think this is OK as is, especially given the documentation.

WDYT?

[nvasilevski]

You could set it back to false via the attr_writer, but not via the ENV var.

In my example I'm showing that it's not possible to reset it using writer after setting it once to true because of how ||= works. If we want to support that, reader will need to be implemented as:

def quiet
    return @quiet if defined(@quiet)

    @quiet = ENV.key?('SPRING_QUIET')
end

[thewoolleyman]

In my example I'm showing that it's not possible to reset it using writer after setting it once to true because of how ||= works.

Ah, gotcha, you're right.

So ideally we can come up with a case where it can be changed from true to false or vice versa, via either the attr_writer or the ENV var.

I'll try to come up with a change that does that and then ping you to review it.

Thanks for your help and attention!

[thewoolleyman]

Sorry, I got busy/lazy and never returned to finish up this thread.

But I see this got merged now, which is great!

This thread describes a minor bug which should be fixed eventually, so I'll keep it on my TODO list - near the bottom, which realistically means "probably never", but hope springs eternal ;)

[nvasilevski]

No worries, there was an additional commit on top of this PR to remove the memoization and make ENV variable to take precedence over a falsey @quiet value

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