Improve health check handling.

Author: samuel-williams-shopify

async-service.gemspec

@@ -27,6 +27,6 @@ Gem::Specification.new do |spec|
 	spec.required_ruby_version = ">= 3.2"
 
 	spec.add_dependency "async"
-	spec.add_dependency "async-container", "~> 0.28"
+	spec.add_dependency "async-container", "~> 0.29"
 	spec.add_dependency "string-format", "~> 0.2"
 end

lib/async/service/health_checker.rb

@@ -28,18 +28,18 @@ def health_checker(instance, timeout = @evaluator.health_check_timeout, parent:
 							# We deliberately create a fiber here, to confirm that fiber creation is working.
 							# If something has gone wrong with fiber allocation, we will crash here, and that's okay.
 							Fiber.new do
-								instance.ready!
+								instance.healthy!
 							end.resume
 
-							sleep(timeout / 2)
+							sleep(timeout / 2.0)
 						end
 					end
 				else
 					if block_given?
 						yield(instance)
 					end
 
-					instance.ready!
+					instance.healthy!
 				end
 			end
 		end

lib/async/service/managed_service.rb

@@ -59,19 +59,21 @@ def start
 			# Override this method to emit metrics, logs, or perform other actions when the service preparation is complete.
 			#
 			# @parameter instance [Async::Container::Instance] The container instance.
-			# @parameter start_time [Async::Clock] The monotonic start time from {Async::Clock.start}.
-			def emit_prepared(instance, start_time)
+			# @parameter clock [Async::Clock] The monotonic start time from {Async::Clock.start}.
+			def emit_prepared(instance, clock)
 				# Override in subclasses as needed.
+				Console.info(self, "Prepared...", duration: clock.total)
 			end
 
 			# Called after the service has started running.
 			#
 			# Override this method to emit metrics, logs, or perform other actions when the service begins running.
 			#
 			# @parameter instance [Async::Container::Instance] The container instance.
-			# @parameter start_time [Async::Clock] The monotonic start time from {Async::Clock.start}.
-			def emit_running(instance, start_time)
+			# @parameter clock [Async::Clock] The monotonic start time from {Async::Clock.start}.
+			def emit_running(instance, clock)
 				# Override in subclasses as needed.
+				Console.info(self, "Running...", duration: clock.total)
 			end
 
 			# Set up the container with health checking and process title formatting.
@@ -83,22 +85,27 @@ def setup(container)
 				health_check_timeout = container_options[:health_check_timeout]
 
 				container.run(**container_options) do |instance|
-					start_time = Async::Clock.start
+					clock = Async::Clock.start
 
 					Async do
 						evaluator = self.environment.evaluator
+						server = nil
+						
+						health_checker(instance, health_check_timeout) do
+							if server
+								instance.name = format_title(evaluator, server)
+							end
+						end
 
 						instance.status!("Preparing...")
 						evaluator.prepare!(instance)
-						emit_prepared(instance, start_time)
+						emit_prepared(instance, clock)
 
 						instance.status!("Running...")
 						server = run(instance, evaluator)
-						emit_running(instance, start_time)
+						emit_running(instance, clock)
 
-						health_checker(instance) do
-							instance.name = format_title(evaluator, server)
-						end
+						instance.ready!
 					end
 				end
 			end

releases.md

@@ -1,5 +1,10 @@
 # Releases
 
+## Unreleased
+
+  - Start health checker earlier in the process. Use `#healthy!` message instead of `#ready!`.
+  - Emit prepared and running log messages with durations (e.g. how long it took to transition to prepared and running states).
+
 ## v0.17.0
 
   - `ManagedService` now sends `status!` messages during startup to prevent premature health check timeouts for slow-starting services.