First pass on an implementation for https://github.com/chef/chef-rfc/pull/305

Signed-off-by: Noah Kantrowitz <noah@coderanger.net>

2 files changed, 48 insertions, 1 deletions

diff --git a/lib/chef/client.rb b/lib/chef/client.rb
index 7218c3bb49..33d625c54e 100644
--- a/lib/chef/client.rb
+++ b/lib/chef/client.rb
@@ -275,6 +275,9 @@ class Chef
 
         do_windows_admin_check
 
+        Chef.resource_handler_map.lock!
+        Chef.provider_handler_map.lock!
+
         run_context = setup_run_context
 
         load_required_recipe(@rest, run_context) unless Chef::Config[:solo_legacy_mode]
diff --git a/lib/chef/node_map.rb b/lib/chef/node_map.rb
index 0406b3c1d6..448e695ca9 100644
--- a/lib/chef/node_map.rb
+++ b/lib/chef/node_map.rb
@@ -45,12 +45,16 @@ class Chef
     # @param key [Object] Key to store
     # @param value [Object] Value associated with the key
     # @param filters [Hash] Node filter options to apply to key retrieval
+    # @param allow_cookbook_override [Boolean] Allow a cookbook to add to this
+    #   key even in locked mode.
+    # @param __core_override__ [Boolean] Advanced-mode override to add to a key
+    #   even in locked mode.
     #
     # @yield [node] Arbitrary node filter as a block which takes a node argument
     #
     # @return [NodeMap] Returns self for possible chaining
     #
-    def set(key, klass, platform: nil, platform_version: nil, platform_family: nil, os: nil, canonical: nil, override: nil, &block)
+    def set(key, klass, platform: nil, platform_version: nil, platform_family: nil, os: nil, canonical: nil, override: nil, allow_cookbook_override: false, __core_override__: false, &block)
       new_matcher = { klass: klass }
       new_matcher[:platform] = platform if platform
       new_matcher[:platform_version] = platform_version if platform_version
@@ -59,6 +63,18 @@ class Chef
       new_matcher[:block] = block if block
       new_matcher[:canonical] = canonical if canonical
       new_matcher[:override] = override if override
+      new_matcher[:cookbook_override] = allow_cookbook_override
+      new_matcher[:core_override] = __core_override__
+
+      # Check if the key is already present and locked, unless the override is allowed.
+      if !__core_override__ && map[key] && map[key].any? {|matcher| matcher[:locked] } && !map[key].any? {|matcher| matcher[:cookbook_override] }
+        type_of_thing = klass.is_a?(Chef::Resource) ? 'resource' : 'provider'
+        # For now, only log the warning.
+        Chef.log_deprecation("Trying to register #{type_of_thing} #{key} on top of existing Chef core #{type_of_thing}. Check if a new version of the cookbook is available.")
+        # In 15.0, uncomment this and remove the log above.
+        # Chef.log_deprecation("Rejecting attempt to register #{type_of_thing} #{key} on top of existing Chef core #{type_of_thing}. Check if a new version of the cookbook is available.")
+        # return
+      end
 
       # The map is sorted in order of preference already; we just need to find
       # our place in it (just before the first value with the same preference level).
@@ -159,6 +175,34 @@ class Chef
       remaining
     end
 
+    # Check if this map has been locked.
+    #
+    # @api internal
+    # @since 14.2
+    # @return [Boolean]
+    def locked?
+      if defined?(@locked)
+        @locked
+      else
+        false
+      end
+    end
+
+    # Set this map to locked mode. This is used to prevent future overwriting
+    # of existing names.
+    #
+    # @api internal
+    # @since 14.2
+    # @return [void]
+    def lock!
+      map.each do |key, matchers|
+        matchers.each do |matcher|
+          matcher[:locked] = true
+        end
+      end
+      @locked = true
+    end
+
     private
 
     #