Improved variable expansion in service definitions.

src/service/service.cr

@@ -190,7 +190,8 @@ class Service
 		end
 	end
 
-	private def build_environment
+	@commands_environment : Hash(String, String)?
+	private def build_commands_environment!
 		env = {} of String => String
 
 		env["SERVICE_NAME"] = name
@@ -223,7 +224,10 @@ class Service
 			env[variable] = value
 		end
 
-		env
+		@commands_environment = env
+	end
+	def commands_environment : Hash(String, String)
+		@commands_environment || build_commands_environment!
 	end
 
 	# FIXME: Is working on ${} really a good idea?
@@ -231,18 +235,12 @@ class Service
 	#        environment, and we should take our variables from that
 	#        instead of hardcoding everything.
 	private def evaluate(string)
+		env = commands_environment
+
 		string.gsub /\${[a-zA-Z_]+}/ do |match|
 			match = match[2..match.size-2]
 
-			if match.downcase == "environment"
-				@environment.name
-			elsif match.downcase == "service_root"
-				root
-			elsif match.downcase == "service_name"
-				name
-			else
-				""
-			end
+			env[match.upcase]? || ""
 		end
 	end
 
@@ -283,7 +281,7 @@ class Service
 				Process.exec "sh", ["-c", creation_command],
 					output: Process::Redirect::Inherit,
 					error: Process::Redirect::Inherit,
-					env: build_environment
+					env: commands_environment
 			end.wait
 
 			unless child.success?
@@ -315,7 +313,7 @@ class Service
 
 			Process.exec command, args,
 				chdir: (@reference.directory.try { |x| evaluate x } || root),
-				env: build_environment
+				env: commands_environment
 		end
 
 		self.save_pid context.pid_directory, process.pid
@@ -489,7 +487,7 @@ class Service
 					Process.exec "sh", ["-c", command],
 						output: Process::Redirect::Inherit,
 						error: Process::Redirect::Inherit,
-						env: build_environment
+						env: commands_environment
 				else
 					FileUtils.rm_rf file_path
 				end