This is a minimal Rails app to demonstrate an uninitialized constant error when using sidekiqswarm (from sidekiq-ent) and Bootsnap with Grape.

The error happens when there is a class that inherits from Grape::API (here being Thing) and a nested class (here Thing::NestedThing). When the nested class is loaded an uninitialized constant error is raised when app is booted with sidekiqswarm and Bootsnap is enabled (which is a Rails default).

bundle install

To reproduce the error, simple run ./bin/sidekiqswarm

This is how the error look like:

/home/guigs/.rbenv/versions/3.0.3/lib/ruby/gems/3.0.0/gems/grape-1.6.2/lib/grape/api.rb:87:in `const_get': uninitialized constant #<Class:0x00007f5b1c6cb2d0>::NestedThing (NameError)
Did you mean?  Thing::NestedThing
        from /home/guigs/.rbenv/versions/3.0.3/lib/ruby/gems/3.0.0/gems/grape-1.6.2/lib/grape/api.rb:87:in `const_missing'
        from /home/guigs/grapeboot/config/routes.rb:8:in `block in <main>'
        from /home/guigs/.rbenv/versions/3.0.3/lib/ruby/gems/3.0.0/gems/actionpack-7.0.3/lib/action_dispatch/routing/route_set.rb:428:in `instance_exec'
        from /home/guigs/.rbenv/versions/3.0.3/lib/ruby/gems/3.0.0/gems/actionpack-7.0.3/lib/action_dispatch/routing/route_set.rb:428:in `eval_block'
        from /home/guigs/.rbenv/versions/3.0.3/lib/ruby/gems/3.0.0/gems/actionpack-7.0.3/lib/action_dispatch/routing/route_set.rb:410:in `draw'
        from /home/guigs/grapeboot/config/routes.rb:1:in `<main>'
        from /home/guigs/.rbenv/versions/3.0.3/lib/ruby/gems/3.0.0/gems/bootsnap-1.11.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:39:in `load'

The error seems to happen regardless of environment (development or production).

When app is started with any of those, the error does not happen:

• rails server
• DISABLE_BOOTSNAP_LOAD_PATH_CACHE=1 ./bin/sidekiqswarm
• SIDEKIQ_PRELOAD= ./bin/sidekiqswarm

It also does not happen if require 'bootsnap/setup' is removed from config/boot.rb.

The error does not happen if bin/sidekiqswarm script is modified to include require 'bootsnap/setup' after require 'bundler/setup'.

But then it requires explicit set of BOOTSNAP_CACHE_DIR env variable. For example:

BOOTSNAP_CACHE_DIR=tmp/cache ./bin/sidekiqswarm

A proper fix should detect if bootsnap is installed and not disabled before requiring it and somehow provide or use default value for BOOTSNAP_CACHE_DIR.