Clockwork on Heroku is failing to load

[kapso]

Clockwork Gem - https://github.com/Rykian/clockwork

Getting this error - ! Unable to load application: NameError: expected file /app/lib/clock.rb to define constant Clock, but didn't

My clock.rb is inside - /APP_ROOT/lib/clock.rb, and not in /APP_ROOT/app/lib/clock.rb

This is my environment on Heroku -

• Rails v6.0
• Ruby v2.6.4
• Zeitwerk v2.1.10

Detailed Error -

2019-09-20T01:16:52.504423+00:00 app[web.1]: ! Unable to load application: NameError: expected file /app/lib/clock.rb to define constant Clock, but didn't
2019-09-20T01:16:52.504612+00:00 app[web.1]: bundler: failed to load command: puma (/app/vendor/bundle/ruby/2.6.0/bin/puma)
2019-09-20T01:16:52.504669+00:00 app[web.1]: NameError: expected file /app/lib/clock.rb to define constant Clock, but didn't
2019-09-20T01:16:52.504672+00:00 app[web.1]: /app/vendor/bundle/ruby/2.6.0/gems/zeitwerk-2.1.10/lib/zeitwerk/loader/callbacks.rb:17:in `on_file_autoloaded'
2019-09-20T01:16:52.504674+00:00 app[web.1]: /app/vendor/bundle/ruby/2.6.0/gems/zeitwerk-2.1.10/lib/zeitwerk/kernel.rb:17:in `block in require'
2019-09-20T01:16:52.504678+00:00 app[web.1]: /app/vendor/bundle/ruby/2.6.0/gems/zeitwerk-2.1.10/lib/zeitwerk/kernel.rb:16:in `tap'
2019-09-20T01:16:52.504681+00:00 app[web.1]: /app/vendor/bundle/ruby/2.6.0/gems/zeitwerk-2.1.10/lib/zeitwerk/kernel.rb:16:in `require'

Adding more info here -

This issue is fixed if I use classic autoloader as suggested here - https://weblog.rubyonrails.org/2019/2/22/zeitwerk-integration-in-rails-6-beta-2/

config.autoloader = :classic

Also,
I have the following in application.rb - config.eager_load_paths += %W[#{config.root}/lib]

[fxn]

From the description, I guess your application has lib in the autoload paths, and that lib/clock.rb defines Clockwork instead of Clock.

If that is right, you have two options:

1. Remove lib from the autoload paths, which is something encouraged generally because lib normally has all sort of things that are not autoloadable (as Rake tasks, for example, or your own use case). In that case, changes in those files won't reload the app.
2. If you absolutely want lib in autoload paths, then you need to say that lib/clock.rb should not really be managed by Zeitwerk: Rails.autoloaders.main.ignore("#{Rails.root}/lib/clock.rb").

[kapso]

@fxn

Yea I have the following in application.rb - because I have a bunch of helper code sitting in APP_ROOT/lib, that I want to be auto-loaded. Or perhaps in Rails 6 (due to zeitwerk), its better to have that code in app/lib/ ??

config.eager_load_paths += %W[#{config.root}/lib]

BTW, I renamed APP_ROOT/lib/clock.rb => APP_ROOT/lib/clockwork.rb and that fixed the issue.

[fxn]

Oh, yes, if renaming the file is an option, that solves the problem too.

Regarding code organization, it all depends on the contents. Question is: Should all *.rb files under lib be autoloadable? If in your app that is true, then your configuration is good.

Otherwise, since lib is in $LOAD_PATH, people just require manually what they need where they need it.

I have also seen app/lib in some apps containing all stuff that has to be autoloaded and that does not belong to the rest of folders in app. That is another possibility.

The important bit is that if Zeitwerk is managing some particular directory, its (non-ignored) file and directory names should match the constants they define. Not doing that is an error condition.

[fxn]

Hey @kapso, do you think we can close this one?

[fxn]

I like to keep issues and PRs to 0 in this project. Since the original issue showed a mismatch in the file name and that has been solved, I believe we can close.

However, please feel free to followup if you'd like to discuss more about code organization.