Problemy z Ruby on Rails - część 1

Zainstalowałem Railsy na moim komputerze Ubuntu i wydaje się, że wszystko działa, oprócz moich prób uruchomienia serwera Railsowego. Zwraca kod błędu informujący, że nokogiri nie jest zainstalowany. Używam „gem install nokigiri” i zwraca to:

    foo@foo:~/myapp$ sudo gem install nokogiri -v '1.8.5' --source 'https://rubygems.org/'
Building native extensions.  This could take a while...
ERROR:  Error installing nokogiri:
    ERROR: Failed to build gem native extension.

    current directory: /var/lib/gems/2.3.0/gems/nokogiri-1.8.5/ext/nokogiri
/usr/bin/ruby2.3 -r ./siteconf20181102-5118-1bvzrgj.rb extconf.rb
checking if the C compiler accepts ... yes
Building nokogiri using packaged libraries.
Using mini_portile version 2.3.0
checking for gzdopen() in -lz... no
zlib is missing; necessary for building libxml2
*** 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=/usr/bin/$(RUBY_BASE_NAME)2.3
    --help
    --clean
    --use-system-libraries
    --enable-static
    --disable-static
    --with-zlib-dir
    --without-zlib-dir
    --with-zlib-include
    --without-zlib-include=${zlib-dir}/include
    --with-zlib-lib
    --without-zlib-lib=${zlib-dir}/lib
    --enable-cross-build
    --disable-cross-build

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

  /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/nokogiri-1.8.5/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /var/lib/gems/2.3.0/gems/nokogiri-1.8.5 for inspection.
Results logged to /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/nokogiri-    1.8.5/gem_make.out

Jestem nowy w Ruby / Rails i nie wiem dokładnie, co zrobić z tym komunikatem o błędzie.