Cannot build the package because chef-gem will not build

[Builder: chef-gem] I | $ /opt/gitlab/embedded/bin/gem install chef --version '12.5.1' --bindir '/opt/gitlab/embedded/bin' --no-ri --no-rdoc
                                    D | Successfully installed mixlib-config-2.2.1
                                    D | Successfully installed mixlib-shellout-2.2.5
                                    D | Successfully installed chef-config-12.5.1
                                    D | Successfully installed mixlib-cli-1.5.0
                                    D | Successfully installed mixlib-log-1.6.0
                                    D | Successfully installed diff-lcs-1.2.5
                                    D | Successfully installed rspec-support-3.4.1
                                    D | Successfully installed rspec-mocks-3.4.0
                                    D | Successfully installed rspec-expectations-3.4.0
                                    D | Successfully installed rspec-core-3.4.1
                                    D | Successfully installed mixlib-authentication-1.4.0.rc.1
                                    D | Building native extensions.  This could take a while...
                                    D | Successfully installed ffi-1.9.10
                                    D | Successfully installed wmi-lite-1.0.0
                                    D | Successfully installed ipaddress-0.8.0
                                    D | Building native extensions.  This could take a while...
                                    D | Successfully installed libyajl2-1.2.0
                                    D | Building native extensions.  This could take a while...
                                    D | ERROR:  Error installing chef:
                                    D | 	rack requires Ruby version >= 2.2.2.
                                    D | Successfully installed ffi-yajl-2.2.2
                                    D | Successfully installed systemu-2.6.5
                                    D | Successfully installed ohai-8.8.1
                                    D | Successfully installed net-ssh-2.10.1.rc2
                                    D | Successfully installed net-ssh-gateway-1.2.0
                                    D | Successfully installed net-ssh-multi-1.2.1
                                    D | Successfully installed highline-1.7.8
                                    D | Successfully installed erubis-2.7.0

Milestone changed to 8.3

Reassigned to @marin

Alpha version of rack got released last week: https://rubygems.org/gems/rack/versions/2.0.0.alpha

Chef 12.5.1 has rack only as development dependency: https://rubygems.org/gems/chef/versions/12.5.1

gem install chef  --version '12.5.1' --bindir '/opt/gitlab/embedded/bin' --no-ri --no-rdoc --explain

Gems to install:
  builder-3.2.2
  chef-12.5.1
  chef-config-12.5.1
  chef-zero-4.4.0
  coderay-1.1.0
  diff-lcs-1.2.5
  erubis-2.7.0
  ffi-1.9.10
  ffi-yajl-2.2.2
  hashie-3.4.3
  highline-1.7.8
  ipaddress-0.8.0
  json-1.8.1
  libyajl2-1.2.0
  method_source-0.8.2
  mixlib-authentication-1.4.0.rc.1
  mixlib-cli-1.5.0
  mixlib-config-2.2.1
  mixlib-log-1.6.0
  mixlib-shellout-2.2.5
  multi_json-1.11.2
  net-scp-1.2.1
  net-ssh-2.10.1.rc2
  net-ssh-gateway-1.2.0
  net-ssh-multi-1.2.1
  net-telnet-0.1.1
  ohai-8.8.1
  plist-3.1.0
  pry-0.10.3
  rack-2.0.0.alpha
  rake-10.1.0
  rspec-3.4.0
  rspec-core-3.4.1
  rspec-expectations-3.4.0
  rspec-its-1.2.0
  rspec-mocks-3.4.0
  rspec-support-3.4.1
  rspec_junit_formatter-0.2.3
  serverspec-2.25.0
  sfl-2.2
  slop-3.6.0
  specinfra-2.47.0
  syslog-logger-1.6.8
  systemu-2.6.5
  uuidtools-2.1.5
  wmi-lite-1.0.0

ERROR:  Error installing chef:
	rack requires Ruby version >= 2.2.2.

Since chef-gem doesn't have a restriction in gemspec, rubygems resolves rack to the latest available version which is 2.0.0.alpha which introduces the ruby contstraint.

Ah, it seems that chef-zero is to blame, it requires rack as a runtime dependency:

gem dependency chef
Gem chef-config-12.5.1
  mixlib-config (~> 2.0)
  mixlib-shellout (~> 2.0)
  rake (~> 10.0, development)
  rspec-core (~> 3.2, development)
  rspec-expectations (~> 3.2, development)
  rspec-mocks (~> 3.2, development)

Gem chef-zero-4.4.0
  ffi-yajl (~> 2.2)
  github_changelog_generator (>= 0, development)
  hashie (< 4.0, >= 2.0)
  mixlib-log (~> 1.3)
  pry (>= 0, development)
  pry-byebug (>= 0, development)
  pry-stack_explorer (>= 0, development)
  rack (>= 0)
  rake (>= 0, development)
  rspec (>= 0, development)
  uuidtools (~> 2.1)

https://github.com/chef/chef-zero/blob/v4.4.0/chef-zero.gemspec#L19

And I found an open PR at chef-zero. PR also references a fix in rubygems 2.3.0.

mentioned in merge request !574 (merged)

Status changed to closed by merge request !574 (merged)

mentioned in commit b1bec3e6