add Chef::Config[:chef_gem_compile_time] plus RELNOTES

* added a config flag to force chef_gem to behave like Chef-10/11
  or to behave like Chef-13.
* added a bunch of release notes to explain the warnings and what to
  do about them in quite a bit of detail.

3 files changed, 18 insertions, 4 deletions

diff --git a/lib/chef/application.rb b/lib/chef/application.rb
index 5a67fc9091..00992fdec1 100644
--- a/lib/chef/application.rb
+++ b/lib/chef/application.rb
@@ -49,6 +49,7 @@ class Chef
       configure_logging
       configure_proxy_environment_variables
       configure_encoding
+      emit_warnings
     end
 
     # Get this party started
@@ -372,6 +373,12 @@ class Chef
       ENV
     end
 
+    def emit_warnings
+      if Chef::Config[:chef_gem_compile_time]
+        Chef::Log.warn "setting chef_gem_compile_time to true is deprecated"
+      end
+    end
+
     class << self
       def debug_stacktrace(e)
         message = "#{e.class}: #{e}\n#{e.backtrace.join("\n")}"
diff --git a/lib/chef/config.rb b/lib/chef/config.rb
index 1a4ec06d98..c9e0914c0b 100644
--- a/lib/chef/config.rb
+++ b/lib/chef/config.rb
@@ -627,6 +627,13 @@ class Chef
     #
     default :no_lazy_load, true
 
+    # Default for the chef_gem compile_time attribute.  Nil is the same as false but will emit
+    # warnings on every use of chef_gem prompting the user to be explicit.  If the user sets this to
+    # true then the user will get backcompat behavior but with a single nag warning that cookbooks
+    # may break with this setting in the future.  The false setting is the recommended setting and
+    # will become the default.
+    default :chef_gem_compile_time, nil
+
     # A whitelisted array of attributes you want sent over the wire when node
     # data is saved.
     # The default setting is nil, which collects all data. Setting to [] will not
diff --git a/lib/chef/resource/chef_gem.rb b/lib/chef/resource/chef_gem.rb
index 126e3d56c3..c95bf03200 100644
--- a/lib/chef/resource/chef_gem.rb
+++ b/lib/chef/resource/chef_gem.rb
@@ -28,7 +28,7 @@ class Chef
       def initialize(name, run_context=nil)
         super
         @resource_name = :chef_gem
-        @compile_time = nil
+        @compile_time = Chef::Config[:chef_gem_compile_time]
         @gem_binary = RbConfig::CONFIG['bindir'] + "/gem"
       end
 
@@ -53,9 +53,9 @@ class Chef
         # Chef::Resource.run_action: Caveat: this skips Chef::Runner.run_action, where notifications are handled
         # Action could be an array of symbols, but probably won't (think install + enable for a package)
         if compile_time.nil?
-          Chef::Log.warn "The chef_gem installation at compile time is deprecated and this behavior will change in the future."
-          Chef::Log.warn "Please set `compile_time false` on the resource to use the new behavior and suppress this warning,"
-          Chef::Log.warn "or you may set `compile_time true` on the resource if compile_time behavior is necessary."
+          Chef::Log.warn "#{self} chef_gem compile_time installation is deprecated"
+          Chef::Log.warn "#{self} Please set `compile_time false` on the resource to use the new behavior."
+          Chef::Log.warn "#{self} or set `compile_time true` on the resource if compile_time behavior is required."
         end
 
         if compile_time || compile_time.nil?