Add support for using deployment spec values within appspec.yml file. These same values are also allowed to be used in the hook scripts: https://blogs.aws.amazon.com/application-management/post/Tx1PX2XMPLYPULD/Using-CodeDeploy-Environment-Variables

Author: Eric Hayes

lib/instance_agent/plugins/codedeploy/application_specification/application_specification.rb

@@ -2,6 +2,8 @@
 require 'instance_agent/plugins/codedeploy/application_specification/file_info'
 require 'instance_agent/plugins/codedeploy/application_specification/linux_permission_info'
 require 'instance_agent/plugins/codedeploy/application_specification/mode_info'
+require 'ostruct'
+require 'erb'
 
 module InstanceAgent
   module Plugins
@@ -23,7 +25,10 @@ def initialize(yaml_hash, opts = {})
             @permissions = parse_permissions(yaml_hash['permissions'] || [])
           end
 
-          def self.parse(app_spec_string)
+          def self.parse(app_spec_template_string, deployment_spec)
+            # make deployment_spec keys available to the yaml template
+            app_spec_string = ERB.new(app_spec_template_string || '').result(OpenStruct.new(deployment_spec).instance_eval { binding })
+
             new(YAML.load(app_spec_string))
           end
 

lib/instance_agent/plugins/codedeploy/command_executor.rb

@@ -199,6 +199,14 @@ def most_recent_deployment_dir(deployment_group)
         def default_app_spec(deployment_spec)
           default_app_spec_location = File.join(archive_root_dir(deployment_spec), app_spec_path)
           log(:debug, "Checking for app spec in #{default_app_spec_location}")
+          app_spec =  ApplicationSpecification::ApplicationSpecification.parse(File.read(default_app_spec_location), {
+            :application_name => deployment_spec.application_name,
+            :deployment_id => deployment_spec.deployment_id,
+            :deployment_group_name => deployment_spec.deployment_group_name,
+            :deployment_group_id => deployment_spec.deployment_group_id,
+            :deployment_root_dir => deployment_root_dir(deployment_spec),
+            :last_successful_deployment_dir => last_successful_deployment_dir(deployment_spec.deployment_group_id)
+          })
           validate_app_spec_hooks(ApplicationSpecification::ApplicationSpecification.parse(File.read(default_app_spec_location)), deployment_spec.all_possible_lifecycle_events)
         end
 

lib/instance_agent/plugins/codedeploy/hook_executor.rb

@@ -227,7 +227,19 @@ def parse_app_spec
                 http://docs.aws.amazon.com/codedeploy/latest/userguide/reference-appspec-file.html
             MESSAGE
           end
-          @app_spec =  InstanceAgent::Plugins::CodeDeployPlugin::ApplicationSpecification::ApplicationSpecification.parse(File.read(app_spec_location))
+          @app_spec =  InstanceAgent::Plugins::CodeDeployPlugin::ApplicationSpecification::ApplicationSpecification.parse(File.read(app_spec_location), deployment_spec)
+        end
+
+        private
+        def deployment_spec
+          {
+            :application_name => @application_name,
+            :deployment_id => @deployment_id,
+            :deployment_group_name => @deployment_group_name,
+            :deployment_group_id => @deployment_group_id,
+            :deployment_root_dir => @current_deployment_root_dir,
+            :last_successful_deployment_dir => @last_successful_deployment_dir
+          }
         end
 
         private

test/instance_agent/plugins/codedeploy/command_executor_test.rb

@@ -152,7 +152,7 @@ def generate_signed_message_for(map)
           stubs(:read).
           with("#@archive_root_dir/appspec.yml").
           returns("APP SPEC")
-          ApplicationSpecification::ApplicationSpecification.stubs(:parse).with("APP SPEC").returns(@app_spec)
+          ApplicationSpecification::ApplicationSpecification.stubs(:parse).with("APP SPEC", {}).returns(@app_spec)
         end
 
         should "create an appropriate Installer" do
@@ -201,7 +201,7 @@ def generate_signed_message_for(map)
           app_spec_hooks = {'UnknownHook' => nil}
           app_spec.expects(:hooks).returns(app_spec_hooks)
           File.stubs(:read).with("#@archive_root_dir/appspec.yml").returns("APP SPEC")
-          ApplicationSpecification::ApplicationSpecification.stubs(:parse).with("APP SPEC").returns(app_spec)
+          ApplicationSpecification::ApplicationSpecification.stubs(:parse).with("APP SPEC", {}).returns(app_spec)
           unknown_hooks = app_spec_hooks.merge(@test_hook_mapping)
           assert_raised_with_message("appspec.yml file contains unknown lifecycle events: #{unknown_hooks.keys}", ArgumentError) do
             @command_executor.execute_command(@command, deployment_spec)
@@ -229,7 +229,7 @@ def generate_signed_message_for(map)
           app_spec_hooks = InstanceAgent::Plugins::CodeDeployPlugin::CommandPoller::DEFAULT_HOOK_MAPPING.merge({'ExampleLifecycleEvent' => nil, 'SecondLifecycleEvent' => nil})
           app_spec.expects(:hooks).twice.returns(app_spec_hooks)
           File.stubs(:read).with("#@archive_root_dir/appspec.yml").returns("APP SPEC")
-          ApplicationSpecification::ApplicationSpecification.stubs(:parse).with("APP SPEC").returns(app_spec)
+          ApplicationSpecification::ApplicationSpecification.stubs(:parse).with("APP SPEC", {}).returns(app_spec)
           assert_raised_with_message("You specified a lifecycle event which is not a default one and doesn't exist in your appspec.yml file: CustomHookNotInAppspec", ArgumentError) do
             @command_executor.execute_command(@command, deployment_spec)
           end