Initial metrics for health check failure.

config/metrics.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2025, by Samuel Williams.
+
+def prepare
+	require "metrics/provider/async/container"
+end

config/sus.rb

@@ -7,3 +7,14 @@
 include Covered::Sus
 
 ENV["CONSOLE_LEVEL"] ||= "fatal"
+ENV["METRICS_BACKEND"] ||= "metrics/backend/test"
+
+def prepare_instrumentation!
+	require "metrics"
+end
+
+def before_tests(...)
+	prepare_instrumentation!
+
+	super
+end

examples/health_check/test.rb

@@ -5,7 +5,8 @@
 # Copyright, 2022, by Anton Sozontov.
 # Copyright, 2024, by Samuel Williams.
 
-require "../../lib/async/container/controller"
+require "metrics"
+require_relative "../../lib/async/container/controller"
 
 NAMES = [
 	"Cupcake", "Donut", "Eclair", "Froyo", "Gingerbread", "Honeycomb", "Ice Cream Sandwich", "Jelly Bean", "KitKat", "Lollipop", "Marshmallow", "Nougat", "Oreo", "Pie", "Apple Tart"

gems.rb

@@ -21,6 +21,8 @@
 	gem "decode"
 	gem "rubocop"
 
+	gem "metrics"
+
 	gem "bake-test"
 	gem "bake-test-external"
 end

lib/async/container/generic.rb

@@ -145,6 +145,13 @@ def stop(timeout = true)
 				@running = true
 			end
 
+			protected def health_check_failed!(child, age_clock, health_check_timeout)
+				Console.warn(self, "Child failed health check!", child: child, age: age_clock.total, health_check_timeout: health_check_timeout)
+
+				# If the child has failed the health check, we assume the worst and kill it immediately:
+				child.kill!
+			end
+
 			# Spawn a child instance into the container.
 			# @parameter name [String] The name of the child instance.
 			# @parameter restart [Boolean] Whether to restart the child instance if it fails.
@@ -176,9 +183,7 @@ def spawn(name: nil, restart: false, key: nil, health_check_timeout: nil, &block
 								case message
 								when :health_check!
 									if health_check_timeout&.<(age_clock.total)
-										Console.warn(self, "Child failed health check!", child: child, age: age_clock.total, health_check_timeout: health_check_timeout)
-										# If the child has failed the health check, we assume the worst and kill it immediately:
-										child.kill!
+										health_check_failed!(child, age_clock, health_check_timeout)
 									end
 								else
 									state.update(message)

lib/metrics/provider/async/container.rb

@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2025, by Samuel Williams.
+
+require_relative "container/generic"

lib/metrics/provider/async/container/generic.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2025, by Samuel Williams.
+
+require_relative "../../../../async/container/generic"
+require "metrics/provider"
+
+Metrics::Provider(Async::Container::Generic) do
+	ASYNC_CONTAINER_GENERIC_HEALTH_CHECK_FAILED = Metrics.metric("async.container.generic.health_check_failed", :counter, description: "The number of health checks that failed.")
+
+	protected def health_check_failed!(child, age_clock, health_check_timeout)
+		ASYNC_CONTAINER_GENERIC_HEALTH_CHECK_FAILED.emit(1)
+
+		super
+	end
+end