Add Knife#config_source(key)

Subclasses can use this to determine where a given
key has received its value from.

This allows subclasses to handle deprecated CLI options
that may still be valid in Chef config by determining
if the option was provided on the CLI or via Chef::Config

Signed-off-by: Marc A. Paradise <marc.paradise@gmail.com>

2 files changed, 35 insertions, 7 deletions

diff --git a/lib/chef/knife.rb b/lib/chef/knife.rb
index b5b32cb193..b1f85386be 100644
--- a/lib/chef/knife.rb
+++ b/lib/chef/knife.rb
@@ -344,8 +344,15 @@ class Chef
     # Chef::Config[:knife] would break the defaults in the cli that we would otherwise
     # overwrite.
     def config_file_settings
+      @key_sources = { cli: [], config: [] }
       cli_keys.each_with_object({}) do |key, memo|
-        memo[key] = Chef::Config[:knife][key] if Chef::Config[:knife].key?(key)
+        if config.key?(key)
+          @key_sources[:cli] << key
+        end
+        if Chef::Config[:knife].key?(key)
+          @key_sources[:config] << key
+          memo[key] = Chef::Config[:knife][key] if Chef::Config[:knife].key?(key)
+        end
       end
     end
 
@@ -356,9 +363,16 @@ class Chef
     def merge_configs
       # other code may have a handle to the config object, so use Hash#replace to deliberately
       # update-in-place.
-      config.replace(
-        default_config.merge(config_file_settings).merge(config)
-      )
+      config.replace(default_config.merge(config_file_settings).merge(config))
+    end
+
+    # Return where a config key has been sourced,
+    # :cli, :config, or nil if the key is not set.
+
+    def config_source(key)
+      return :cli if @key_sources[:cli].include? key
+      return :config if @key_sources[:config].include? key
+      nil
     end
 
     # Catch-all method that does any massaging needed for various config
diff --git a/spec/unit/knife_spec.rb b/spec/unit/knife_spec.rb
index ff89bc6f30..f48ab4019c 100644
--- a/spec/unit/knife_spec.rb
+++ b/spec/unit/knife_spec.rb
@@ -299,7 +299,7 @@ describe Chef::Knife do
         expect(Chef::Config[:log_level]).to eql(:warn)
       end
 
-      it "prefers the default value if no config or command line value is present" do
+      it "prefers the default value if no config or command line value is present and reports the source as default" do
         knife_command = KnifeSpecs::TestYourself.new([]) # empty argv
         knife_command.configure_chef
         expect(knife_command.config[:opt_with_default]).to eq("default-value")
@@ -310,18 +310,32 @@ describe Chef::Knife do
         knife_command = KnifeSpecs::TestYourself.new([]) # empty argv
         knife_command.configure_chef
         expect(knife_command.config[:opt_with_default]).to eq("from-knife-config")
+        expect(knife_command.config_source(:opt_with_default)).to eq (:config)
       end
 
-      it "prefers a value from command line over Chef::Config and the default" do
+      it "correctly reports Chef::Config as the source when a a config entry comes from there" do
         Chef::Config[:knife][:opt_with_default] = "from-knife-config"
+        knife_command = KnifeSpecs::TestYourself.new([]) # empty argv
+        knife_command.configure_chef
+        expect(knife_command.config_source(:opt_with_default)).to eq (:config)
+      end
+
+      it "prefers a value from command line over Chef::Config and the default and reports the source as CLI" do
         knife_command = KnifeSpecs::TestYourself.new(["-D", "from-cli"])
         knife_command.configure_chef
         expect(knife_command.config[:opt_with_default]).to eq("from-cli")
+        expect(knife_command.config_source(:opt_with_default)).to eq (:cli)
+      end
+      it "correctly reports CLI as the source when a config entry comes from the CLI" do
+        knife_command = KnifeSpecs::TestYourself.new(["-D", "from-cli"])
+        knife_command.configure_chef
+        expect(knife_command.config_source(:opt_with_default)).to eq (:cli)
       end
 
       it "merges `listen` config to Chef::Config" do
-        Chef::Knife.run(%w{test yourself --no-listen}, Chef::Application::Knife.options)
+        knife_command = Chef::Knife.run(%w{test yourself --no-listen}, Chef::Application::Knife.options)
         expect(Chef::Config[:listen]).to be(false)
+        expect(knife_command.config_source(:listen)).to eq(:cli)
       end
 
       context "verbosity is one" do