環境

windows11

Rails 6.0.4.1
rmagick 2.16.0

症状

rmagicをGemに記載した後、「bundle install」を実行したときに、下記のエラーメッセージが表示されました。翻訳すると、「rmagick（2.16.0）のインストール中にエラーが発生し、Bundlerを続行できません。」でした。

error

$ bundle install

(中略)

Fetching rmagick 2.16.0
Installing rmagick 2.16.0 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

current directory:
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/rmagick-2.16.0/ext/RMagick
C:/Ruby30-x64/bin/ruby.exe -I C:/Ruby30-x64/lib/ruby/3.0.0 -r
./siteconf20220406-63964-z6t4vr.rb extconf.rb 
*** 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=C:/Ruby30-x64/bin/$(RUBY_BASE_NAME)
extconf.rb:141:in ``': No such file or directory - identify -version
(Errno::ENOENT)
        from extconf.rb:141:in `configure_compile_options'
        from extconf.rb:16:in `initialize'    
        from extconf.rb:548:in `new'
        from extconf.rb:548:in `<main>'       

extconf failed, exit code 1

Gem files will remain installed in
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/rmagick-2.16.0 for inspection.
Results logged to
C:/Ruby30-x64/lib/ruby/gems/3.0.0/extensions/x64-mingw32/3.0.0/rmagick-2.16.0/gem_make.out  

  C:/Ruby30-x64/lib/ruby/3.0.0/rubygems/ext/builder.rb:91:in `run'
C:/Ruby30-x64/lib/ruby/3.0.0/rubygems/ext/ext_conf_builder.rb:48:in `block in
build'
  C:/Ruby30-x64/lib/ruby/3.0.0/tempfile.rb:317:in `open'
  C:/Ruby30-x64/lib/ruby/3.0.0/rubygems/ext/ext_conf_builder.rb:28:in `build'
  C:/Ruby30-x64/lib/ruby/3.0.0/rubygems/ext/builder.rb:157:in `build_extension'
C:/Ruby30-x64/lib/ruby/3.0.0/rubygems/ext/builder.rb:191:in `block in
build_extensions'
  C:/Ruby30-x64/lib/ruby/3.0.0/rubygems/ext/builder.rb:188:in `each'
  C:/Ruby30-x64/lib/ruby/3.0.0/rubygems/ext/builder.rb:188:in `build_extensions'
  C:/Ruby30-x64/lib/ruby/3.0.0/rubygems/installer.rb:828:in `build_extensions'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/rubygems_gem_installer.rb:66:in
`build_extensions'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/rubygems_gem_installer.rb:26:in
`install'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/source/rubygems.rb:192:in 
`install'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/installer/gem_installer.rb:54:in
`install'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/installer/gem_installer.rb:16:in
`install_from_spec'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/installer/parallel_installer.rb:186:in
`do_install'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/installer/parallel_installer.rb:171:in
`install_serially'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/installer/parallel_installer.rb:97:in
`call'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/installer/parallel_installer.rb:71:in
`call'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/installer.rb:263:in       
`install_in_parallel'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/installer.rb:210:in       
`install'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/installer.rb:90:in        
`block in run'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/process_lock.rb:12:in     
`block in lock'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/process_lock.rb:9:in      
`open'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/process_lock.rb:9:in      
`lock'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/installer.rb:72:in        
`run'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/installer.rb:24:in        
`install'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/cli/install.rb:60:in      
`run'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/cli.rb:252:in
`block in install'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/settings.rb:131:in        
`temporary'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/cli.rb:251:in
`install'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/vendor/thor/lib/thor/command.rb:27:in
`run'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/vendor/thor/lib/thor/invocation.rb:127:in
`invoke_command'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/vendor/thor/lib/thor.rb:392:in
`dispatch'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/cli.rb:31:in
`dispatch'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/vendor/thor/lib/thor/base.rb:485:in
`start'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/cli.rb:25:in
`start'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/exe/bundle:49:in `block
in <top (required)>'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/lib/bundler/friendly_errors.rb:128:in 
`with_friendly_errors'
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/bundler-2.2.26/exe/bundle:37:in `<top
(required)>'
  C:/Ruby30-x64/bin/bundle:23:in `load'       
  C:/Ruby30-x64/bin/bundle:23:in `<main>'     

An error occurred while installing rmagick (2.16.0), and Bundler cannot
continue.

In Gemfile:
  rmagick

解決策

ImageMagickを入れることで解決しました。

まずは、ImageMagickをいれていきます。
rmagickは新しめの7バージョンのものがうまく対応されてないようなので、6バージョンのものを入れる必要があります。
下記サイトから入れました。
自分の環境はwindowsなので、OSに合ったものを選びます。

入っていることをバージョン確認で確認しました。

バージョン確認

$convert --version  
Version: ImageMagick 6.9.12-44 Q16-HDRI x64 b350dd1:20220327 https://imagemagick.org
Copyright: (C) 1999 ImageMagick Studio LLC
License: https://imagemagick.org/script/license.php
Visual C++: 193131104
Features: Cipher DPC HDRI Modules OpenCL OpenMP(2.0)
Delegates (built-in): bzlib cairo flif freetype gslib heic jng jp2 jpeg lcms lqr lzma openexr pangocairo png ps raqm raw rsvg tiff webp xml zlib

詳細な手順は下記に書きました

参考