ruby:2.5.1-slim or ruby-2.5.1-alpine fails on nokogiri gem

Question

FROM ruby:2.5.1-slim or ruby-2.5.1-alpine throws the following error, how I do use a smaller footprint for ruby as it doesn't seem to be using any of the above options which I would prefer to use. This error happens while running the bundle install command

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

current directory: /usr/local/bundle/gems/nokogiri-1.8.4/ext/nokogiri
/usr/local/bin/ruby -r ./siteconf20180828-6-l5tj3e.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/local/bin/$(RUBY_BASE_NAME)
--help
--clean
/usr/local/lib/ruby/2.5.0/mkmf.rb:456:in `try_do': The compiler failed to
generate an executable file. (RuntimeError)
You have to install development tools first.
from /usr/local/lib/ruby/2.5.0/mkmf.rb:574:in `block in try_compile'
from /usr/local/lib/ruby/2.5.0/mkmf.rb:521:in `with_werror'
from /usr/local/lib/ruby/2.5.0/mkmf.rb:574:in `try_compile'
from extconf.rb:138:in `nokogiri_try_compile'
from extconf.rb:162:in `block in add_cflags'
from /usr/local/lib/ruby/2.5.0/mkmf.rb:632:in `with_cflags'
from extconf.rb:161:in `add_cflags'
from extconf.rb:410:in `<main>'

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

/usr/local/bundle/extensions/x86_64-linux/2.5.0/nokogiri-1.8.4/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /usr/local/bundle/gems/nokogiri-1.8.4 for
inspection.
Results logged to
/usr/local/bundle/extensions/x86_64-linux/2.5.0/nokogiri-1.8.4/gem_make.out

An error occurred while installing nokogiri (1.8.4), and Bundler cannot
continue.
Make sure that `gem install nokogiri -v '1.8.4' --source 'http://rubygems.org/'`
succeeds before bundling.

In Gemfile:
rails was resolved to 5.2.1, which depends on
actioncable was resolved to 5.2.1, which depends on
actionpack was resolved to 5.2.1, which depends on
actionview was resolved to 5.2.1, which depends on
rails-dom-testing was resolved to 2.0.3, which depends on
nokogiri
The command '/bin/sh -c bundle install --without development test' returned a non-zero code: 5

Answer 1

First of all, try to run gem install nokogiri manually and check the log as suggested in the output above:

...

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

/usr/local/bundle/extensions/x86_64-linux/2.5.0/nokogiri-1.8.4/mkmf.log


...

I recently had a problem while installing the nokogiri gem too. So I opened my mkmf.log file and found the reason of the problem there (the stdio.h library was missing out of the distribution):

"gcc -o conftest -I/usr/local/include/ruby-2.5.0/x86_64-linux-musl -I/usr/local/include/ruby-2.5.0/ruby/backward -I/usr/local/include/ruby-2.5.0 -I.    -O3 -ggdb3 -Wall -Wextra -Wno-unused-parameter -Wno-parentheses -Wno-long-long -Wno-missing-field-initializers -Wno-tautological-compare -Wno-parentheses-equality -Wno-constant-logical-operand -Wno-self-assign -Wunused-variable -Wimplicit-int -Wpointer-arith -Wwrite-strings -Wdeclaration-after-statement -Wimplicit-function-declaration -Wdeprecated-declarations -Wmisleading-indentation -Wno-packed-bitfield-compat -Wsuggest-attribute=noreturn -Wsuggest-attribute=format -Wduplicated-cond -Wno-maybe-uninitialized  -fPIC  conftest.c  -L. -L/usr/local/lib -Wl,-rpath,/usr/local/lib -L. -fstack-protector -rdynamic -Wl,-export-dynamic     -Wl,-rpath,/usr/local/lib -L/usr/local/lib -lruby  -lpthread -ldl -lcrypt -lm   -lc "
In file included from /usr/local/include/ruby-2.5.0/ruby/ruby.h:29:0,
                 from /usr/local/include/ruby-2.5.0/ruby.h:33,
                 from conftest.c:1:
/usr/local/include/ruby-2.5.0/ruby/defines.h:112:19: fatal error: stdio.h: No such file or directory
 #include <stdio.h>
                   ^
compilation terminated.
checked program was:
/* begin */
1: #include "ruby.h"
2: 
3: int main(int argc, char **argv)
4: {
5:   return 0;
6: }
/* end */

The problem was solved by installing the libc-dev package for me.

So. To solve your problem you should iteratively run gem install nokogiri command, check mkmf.log file after each failure and fix missing dependencies until the package is installed.

BTW here's my final list of dependencies which was enough to install Rails in Alpine:

echo "http://dl-cdn.alpinelinux.org/alpine/edge/testing" >> /etc/apk/repositories \
  && apk update \
  && apk add --update-cache postgresql-client nodejs \
    libffi-dev readline sqlite build-base postgresql-dev \
    libc-dev linux-headers libxml2-dev libxslt-dev readline-dev gcc libc-dev \
  && rm -rf /var/cache/apk/*

Answer 2

try this: run sudo gem install nokogiri. It will install the latest version of nokogiri. Then update the version of nokogiri in your Gemfile.lock file to the latest version of nokogiri you juste installed. And finally run bundle install. Maybe it'll help. Worked for me.