Gem installation fails on MacOS

I cannot install this gem on MacOS (Monterey / Intel / Ruby 3.1.2).

This is the error message:

$ brew install rocksdb
Warning: rocksdb 7.5.3 is already installed and up-to-date.
To reinstall 7.5.3, run:
  brew reinstall rocksdb
$ gem install rocksdb-ruby
Building native extensions. This could take a while...
ERROR:  Error installing rocksdb-ruby:
	ERROR: Failed to build gem native extension.

    current directory: /Users/collimarco/.rbenv/versions/3.1.2/lib/ruby/gems/3.1.0/gems/rocksdb-ruby-1.0.2/ext/rocksdb
/Users/collimarco/.rbenv/versions/3.1.2/bin/ruby -I /Users/collimarco/.rbenv/versions/3.1.2/lib/ruby/3.1.0 -r ./siteconf20220907-11247-eq0d9k.rb extconf.rb
checking for -lrocksdb_debug... no
checking for rocksdb/db.h... no
can't find header or library of rocksdb
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
	--with-opt-dir
	--without-opt-dir
	--with-opt-include
	--without-opt-include=${opt-dir}/include
	--with-opt-lib
	--without-opt-lib=${opt-dir}/lib
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=/Users/collimarco/.rbenv/versions/3.1.2/bin/$(RUBY_BASE_NAME)
	--with-rocksdb-dir
	--without-rocksdb-dir
	--with-rocksdb-include
	--without-rocksdb-include=${rocksdb-dir}/include
	--with-rocksdb-lib
	--without-rocksdb-lib=${rocksdb-dir}/lib
	--with-rocksdb_debug-dir
	--without-rocksdb_debug-dir
	--with-rocksdb_debug-include
	--without-rocksdb_debug-include=${rocksdb_debug-dir}/include
	--with-rocksdb_debug-lib
	--without-rocksdb_debug-lib=${rocksdb_debug-dir}/lib
	--with-rocksdb_debuglib
	--without-rocksdb_debuglib

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /Users/collimarco/.rbenv/versions/3.1.2/lib/ruby/gems/3.1.0/extensions/x86_64-darwin-21/3.1.0/rocksdb-ruby-1.0.2/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /Users/collimarco/.rbenv/versions/3.1.2/lib/ruby/gems/3.1.0/gems/rocksdb-ruby-1.0.2 for inspection.
Results logged to /Users/collimarco/.rbenv/versions/3.1.2/lib/ruby/gems/3.1.0/extensions/x86_64-darwin-21/3.1.0/rocksdb-ruby-1.0.2/gem_make.out

I would love to use this gem and any help would be appreciated.

Start by reproducing the reported gem install rocksdb-ruby failure on macOS with Ruby 3.1.2 and Homebrew RocksDB. Inspect ext/rocksdb/extconf.rb, the generated mkmf.log, and the native extension build output to determine why rocksdb/db.h and the library are not found. Done means the gem installs successfully in the reported environment.