Add ipv6 disable check

(cherry picked from commit e19db77)

definitions/checks/check_ipv6_disable.rb

@@ -0,0 +1,23 @@
+class Checks::CheckIpv6Disable < ForemanMaintain::Check
+  metadata do
+    label :check_ipv6_disable
+    description 'Check if ipv6.disable=1 is set at kernel level'
+  end
+
+  def run
+    cmdline_file = File.read('/proc/cmdline')
+
+    assert(!cmdline_file.include?("ipv6.disable=1"), error_message)
+  end
+
+  def error_message
+    base = "\nThe kernel contains ipv6.disable=1 which is known to break installation and upgrade"\
+           ", remove and reboot before continuining."
+
+    if feature(:instance).downstream
+      base += " See https://access.redhat.com/solutions/5045841 for more details."
+    end
+
+    base
+  end
+end

definitions/scenarios/upgrade_to_capsule_6_15.rb

@@ -27,6 +27,7 @@ class PreUpgradeCheck < Abstract
     def compose
       add_steps(find_checks(:default))
       add_steps(find_checks(:pre_upgrade))
+      add_step(Checks::CheckIpv6Disable)
       add_step(Checks::Repositories::Validate.new(:version => '6.15'))
     end
   end

definitions/scenarios/upgrade_to_capsule_6_15_z.rb

@@ -27,6 +27,7 @@ class PreUpgradeCheck < Abstract
     def compose
       add_steps(find_checks(:default))
       add_steps(find_checks(:pre_upgrade))
+      add_step(Checks::CheckIpv6Disable)
       add_step(Checks::Repositories::Validate.new(:version => '6.15'))
     end
   end

definitions/scenarios/upgrade_to_satellite_6_15.rb

@@ -27,6 +27,7 @@ class PreUpgradeCheck < Abstract
     def compose
       add_steps(find_checks(:default))
       add_steps(find_checks(:pre_upgrade))
+      add_step(Checks::CheckIpv6Disable)
       add_step(Checks::Repositories::Validate.new(:version => '6.15'))
     end
   end

definitions/scenarios/upgrade_to_satellite_6_15_z.rb

@@ -27,6 +27,7 @@ class PreUpgradeCheck < Abstract
     def compose
       add_steps(find_checks(:default))
       add_steps(find_checks(:pre_upgrade))
+      add_step(Checks::CheckIpv6Disable)
       add_step(Checks::Repositories::Validate.new(:version => '6.15'))
     end
   end

test/definitions/checks/check_ipv6_disable_test.rb

@@ -0,0 +1,21 @@
+require 'test_helper'
+
+describe Checks::CheckIpv6Disable do
+  include DefinitionsTestHelper
+
+  subject { Checks::CheckIpv6Disable.new }
+
+  it 'throws an error message when ipv6.disable=1 is set' do
+    File.expects(:read).with('/proc/cmdline').returns('ipv6.disable=1')
+    result = run_step(subject)
+
+    assert result.fail?
+  end
+
+  it 'success when ipv6.disable=1 is not set' do
+    File.expects(:read).with('/proc/cmdline').returns('test.net=0')
+    result = run_step(subject)
+
+    assert result.success?
+  end
+end