Redmine

Hello all,

While running bundle install --without development test I get error occurred while installing json (1.8.6)

I'm following the steps from Redmine install exactly. http://www.redmine.org/projects/redmine/wiki/RedmineInstall

Prep steps include
- svn co https://svn.redmine.org/redmine/branches/3.3-stable redmine-3.3
- Edit database.yml for correct DB.
- Creating DB and setting permissions

1. apt install ruby
2. gem install bundler
3. bundle install --without development test

Full Output

Fetching gem metadata from https://rubygems.org/..........
Fetching version metadata from https://rubygems.org/..
Fetching dependency metadata from https://rubygems.org/.
Resolving dependencies...
Rubygems 1.8.23 is not threadsafe, so your gems will be installed one at a time. Upgrade to Rubygems 2.1.0 or higher to enable parallel gem installation.
Installing rake 12.0.0
Installing i18n 0.7.0
Installing json 1.8.6 with native extensions
Installing minitest 5.10.1
Installing thread_safe 0.3.6
Installing builder 3.2.3
Installing erubis 2.7.0
Installing mini_portile2 2.1.0
Installing rack 1.6.5
Installing mime-types 2.99.3
Installing arel 6.0.4
Installing addressable 2.4.0
Using bundler 1.14.6
Installing coderay 1.1.1
Installing concurrent-ruby 1.0.5
Installing htmlentities 4.3.4
Installing thor 0.19.4
Installing mimemagic 0.3.2
Installing net-ldap 0.12.1
Installing ruby-openid 2.3.0
Installing rbpdf-font 1.19.1
Installing redcarpet 3.3.4 with native extensions
Installing request_store 1.0.5
Installing rmagick 2.16.0 with native extensions
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native
extension.

        /usr/bin/ruby1.9.1 extconf.rb
/usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require': cannot load such
file -- mkmf (LoadError)
        from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
        from extconf.rb:1:in `<main>'

Gem files will remain installed in /var/lib/gems/1.9.1/gems/json-1.8.6 for
inspection.
Results logged to
/var/lib/gems/1.9.1/gems/json-1.8.6/ext/json/ext/generator/gem_make.out

An error occurred while installing json (1.8.6), and Bundler cannot
continue.
Make sure that `gem install json -v '1.8.6'` succeeds before bundling.

Environment
I started with a clean Ubuntu 16 server all up to date and including LAMP stack. All latest (or close to it).
Gem list shows json (1.8.3) installed.
Running ruby 2.3.1p112 (2016-04-26) [x86_64-linux-gnu]
Gem v 2.5.1

Troubleshooting
I've tried spinning up an Ubutnu 14 machine fresh and I get the same error.

Based on this thread: http://www.redmine.org/boards/2/topics/29070?r=45423#message-45423
I tried the following:
Remove .bundle/config if present then try:
bundle install --without development test rmagick
This should skip the json gem installation which is not needed to run Redmine.

It did not work. The error is exactly the same.

Any help would be great.
Thank you