FFI fails when required under rack

[ayoshi]

I have created a simple test app:

#\ -p 9292

require "ffi"

run ->(env) { [200, {"Content-Type" => "text/html"}, ["Hello World!"]] }

Running it fails:

root@b6335697b39b:/app# rackup -E none -o 0.0.0.0 -d -s thin test_ffi2.ru
"thin"
Exception `LoadError' at /usr/local/bundle/gems/ffi-1.9.14/lib/ffi.rb:4 - cannot load such file -- 2.2/ffi_c
#<Proc:0x005627e377fa68@/app/test_ffi2.ru:5 (lambda)>
#<Proc:0x005627e377fa68@/app/test_ffi2.ru:5 (lambda)>
Thin web server (v1.6.4 codename Gob Bluth)
Maximum connections set to 1024
Listening on 0.0.0.0:9292, CTRL+C to stop

The same code runs with regular ruby with no problem

ruby -e 'require "ffi"'

Gives out no errors, the more complicated code works too:

require "ffi"

puts "libc => #{FFI::Library::LIBC}"
puts FFI::Platform
ffi_lib(FFI::Platform::LIBC)
puts "successfully loaded: #{ffi_libraries}"

root@b6335697b39b:/app# ruby  test_ffi.rb
libc => libc.so.6
successfully loaded: [#<FFI::DynamicLibrary:0x00564f0c7481d0 @name="libc.so.6">]

I've been pulling my hair out for 3 straight days. The real code inside handlers uses FFI several layers deeper, and of course it fails.

I'm running the tests under the official ruby:2.2.4 docker image.

Versions:

ruby 2.2.4p230 (2015-12-16 revision 53155) [x86_64-linux]
ffi (1.9.14)
rack (1.6.4)
rack-cors (0.4.0)
rack-mini-profiler (0.10.1)
rack-protection (1.5.3)
rack-test (0.6.3)

[ayoshi]

Oh, I forgot to mention: running under rack-2 and thin 1.7.0 fails too:

root@b6335697b39b:/app# rackup -E none -o 0.0.0.0 -d -s thin test_ffi2.ru
"thin"
Exception `LoadError' at /usr/local/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:55 - cannot load such file -- ffi
Exception `LoadError' at /usr/local/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:55 - cannot load such file -- 2.2/ffi_c
Exception `LoadError' at /usr/local/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:135 - cannot load such file -- 2.2/ffi_c
#<Proc:0x00562dffca4170@/app/test_ffi2.ru:5 (lambda)>
#<Proc:0x00562dffca4170@/app/test_ffi2.ru:5 (lambda)>
Exception `LoadError' at /usr/local/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:55 - cannot load such file -- thin
Exception `LoadError' at /usr/local/lib/ruby/2.2.0/resolv.rb:168 - LoadError
Thin web server (v1.7.0 codename Dunder Mifflin)
Maximum connections set to 1024
Listening on 0.0.0.0:9292, CTRL+C to stop

[ayoshi]

I had also performed an experiment installing ruby with Rvm on a standard Ubuntu image and hit the same errors.

[dillonwelch]

@ayoshi there's been a lot of version changes in ruby, rack, etc since you reported this issue. Would you be able to use the latest version of the gems and see if this is still a problem?

[jeremyevans]

The example given here isn't failing, it's simply printing exceptions because it is run in debug mode. You get the same errors when requiring directly in debug mode:

$ ruby -d -e 'require "ffi"'
Exception `LoadError' at /usr/local/lib/ruby/2.6/rubygems.rb:1375 - cannot load such file -- rubygems/defaults/operating_system
Exception `LoadError' at /usr/local/lib/ruby/2.6/rubygems.rb:1384 - cannot load such file -- rubygems/defaults/ruby
Exception `LoadError' at /usr/local/lib/ruby/2.6/rubygems/core_ext/kernel_require.rb:54 - cannot load such file -- ffi
Exception `LoadError' at /usr/local/lib/ruby/2.6/rubygems/core_ext/kernel_require.rb:54 - cannot load such file -- 2.6/ffi_c
Exception `LoadError' at /usr/local/lib/ruby/2.6/rubygems/core_ext/kernel_require.rb:132 - cannot load such file -- 2.6/ffi_c

Even if the output given, you can see the webserver still starts up and is listening:

Maximum connections set to 1024
Listening on 0.0.0.0:9292, CTRL+C to stop