Issue #19189 has been updated by yahonda (Yasuo Honda). I think Rails CI is also affected by https://github.com/ruby/ruby/commit/7f1ca666424849134990d022266bcd4d6636465f Details are https://github.com/rails/rails/pull/46711#issuecomment-1348396867 ---------------------------------------- Bug #19189: Ruby 3.1.3/3.2.x can no longer find pkg-config if not present at buildtime https://bugs.ruby-lang.org/issues/19189#change-100622 * Author: mistydemeo (Misty De Meo) * Status: Open * Priority: Normal * ruby -v: ruby 3.1.3p185 (2022-11-24 revision 1a6b16756e) [x86_64-linux] * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN ---------------------------------------- Starting with Ruby 3.1.3, mkmf.rb calls to `pkg-config` will fail if `pkg-config` wasn't present on the system at the time it was built. Prior to that version, even if Ruby itself wasn't configured with `pkg-config`, mkmf.rb would be able to correctly pick it up from the `PATH`. This was introduced by https://github.com/ruby/ruby/commit/7f1ca666424849134990d022266bcd4d6636465f and its Ruby 3.1.3 equivalent, https://github.com/ruby/ruby/commit/3914581213e3aea138b02941b41e62c15461af27. I've confirmed that reverting this specific change fixes the problem. This broke a Ruby deployment which is built in a minimal Docker environment with no `pkg-config`, but which is later copied into a system with `pkg-config` present. -- https://bugs.ruby-lang.org/