How to install Nokogiri with Rails on Ubuntu 16.04 - ruby

Question

I am trying to install Rails by using
sudo gem install rails
on a fresh version of Ubuntu 16.04. Ruby 2.3.1p112 is already installed. During the installation of Rails, once fetching Nokogiri is complete, I get the error below:
Fetching: nokogiri-1.8.0.gem (100%)
Building native extensions. This could take a while...
ERROR: Error installing rails:
ERROR: Failed to build gem native extension.
current directory: /var/lib/gems/2.3.0/gems/nokogiri-1.8.0/ext/nokogiri
/usr/bin/ruby2.3 -r ./siteconf20170608-1635-1vnwqbn.rb extconf.rb
checking if the C compiler accepts ... *** 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
/usr/lib/ruby/2.3.0/mkmf.rb:456:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
from /usr/lib/ruby/2.3.0/mkmf.rb:571:in `block in try_compile'
from /usr/lib/ruby/2.3.0/mkmf.rb:522:in `with_werror'
from /usr/lib/ruby/2.3.0/mkmf.rb:571:in `try_compile'
from extconf.rb:138:in `nokogiri_try_compile'
from extconf.rb:162:in `block in add_cflags'
from /usr/lib/ruby/2.3.0/mkmf.rb:629:in `with_cflags'
from extconf.rb:161:in `add_cflags'
from extconf.rb:407:in `<main>'
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-1.8.0/mkmf.log
extconf failed, exit code 1
Gem files will remain installed in /var/lib/gems/2.3.0/gems/nokogiri-1.8.0 for inspection.
Results logged to /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/nokogiri-1.8.0/gem_make.out
This is the content of mkmf.log:
"gcc -o conftest -I/usr/include/x86_64-linux-gnu/ruby-2.3.0 -I/usr/include/ruby-2.3.0/ruby/backward -I/usr/include/ruby-2.3.0 -I. -Wdate-time -D_FORTIFY_SOURCE=2 -g -O2 -fstack-protector-strong -Wformat -Werror=format-security -fPIC conftest.c -L. -L/usr/lib/x86_64-linux-gnu -L. -Wl,-Bsymbolic-functions -Wl,-z,relro -Wl,-z,now -fstack-protector -rdynamic -Wl,-export-dynamic -lruby-2.3 -lpthread -lgmp -ldl -lcrypt -lm -lc "
checked program was:
/* begin */
1: #include "ruby.h"
2:
3: int main(int argc, char **argv)
4: {
5: return 0;
6: }
/* end */
I have no idea what is wrong. The log does not help and I already tried installing libgmp-dev, ruby-dev, zlib1g-dev and liblzma-dev as they were suggested to people who are getting errors during Nokogiri gem installation.

Answer 1

After trying to find the missing dependency for a while, I ran the gcc command in the mkmf.log just in case some compilation error messages are being omitted.
It turned out that I didn't have gcc installed. Once I installed it, I got some progress with the installation only to encounter another similar error. In the end, installing the dependencies below resulted in a successful installation of Rails.
Please make sure you have gcc, make, zlib1g-dev, sqlite3 installed before running gem install rails:
sudo apt-get install gcc make zlib1g-dev sqlite3