revert logger to non optional

Author: nervenes

Sources/ServiceLifecycle/Docs.docc/How to adopt ServiceLifecycle in applications.md

@@ -69,15 +69,23 @@ on services with a lower index. The following example shows how this can be
 applied to our `BarService`.
 
 ```swift
+import ServiceLifecycle
+import Logging
+
 @main
 struct Application {
+  static let logger = Logger(label: "Application")
+
   static func main() async throws {
     let fooService = FooServer()
     let barService = BarService(fooService: fooService)
 
+
+
     let serviceGroup = ServiceGroup(
       // We are encoding the dependency hierarchy here by listing the fooService first
-      services: [fooService, barService]
+      services: [fooService, barService],
+      logger: logger
     )
 
     try await serviceGroup.run()
@@ -109,6 +117,9 @@ A common example of this is for applications that implement streaming
 behaviours.
 
 ```swift
+import ServiceLifecycle
+import Logging
+
 struct StreamingService: Service {
   struct RequestStream: AsyncSequence { ... }
   struct ResponseWriter {
@@ -134,6 +145,8 @@ struct StreamingService: Service {
 
 @main
 struct Application {
+  static let logger = Logger(label: "Application")
+
   static func main() async throws {
     let streamingService = StreamingService(streamHandler: { requestStream, responseWriter in
       for await request in requestStream {
@@ -143,7 +156,8 @@ struct Application {
 
     let serviceGroup = ServiceGroup(
       services: [streamingService],
-      gracefulShutdownSignals: [.sigterm]
+      gracefulShutdownSignals: [.sigterm],
+      logger: logger
     )
 
     try await serviceGroup.run()
@@ -168,6 +182,9 @@ and what we want to do is stop the iteration. To do this we can use the
 `AsyncSequence`. The updated code looks like this:
 
 ```swift
+import ServiceLifecycle
+import Logging
+
 struct StreamingService: Service {
   struct RequestStream: AsyncSequence { ... }
   struct ResponseWriter {
@@ -193,6 +210,8 @@ struct StreamingService: Service {
 
 @main
 struct Application {
+  static let logger = Logger(label: "Application")
+
   static func main() async throws {
     let streamingService = StreamingService(streamHandler: { requestStream, responseWriter in
       for await request in requestStream.cancelOnGracefulShutdown() {
@@ -202,7 +221,8 @@ struct Application {
 
     let serviceGroup = ServiceGroup(
       services: [streamingService],
-      gracefulShutdownSignals: [.sigterm]
+      gracefulShutdownSignals: [.sigterm],,
+      logger: logger
     )
 
     try await serviceGroup.run()
@@ -239,8 +259,13 @@ sure your telemetry service is gracefully shutdown after your HTTP server
 unexpectedly threw from its `run()` method. This setup could look like this:
 
 ```swift
+import ServiceLifecycle
+import Logging
+
 @main
 struct Application {
+  static let logger = Logger(label: "Application")
+
   static func main() async throws {
     let telemetryService = TelemetryService()
     let httpServer = HTTPServer()
@@ -254,7 +279,8 @@ struct Application {
             successTerminationBehavior: .shutdownGracefully,
             failureTerminationBehavior: .shutdownGracefully
           )
-        ]
+        ],
+        logger: logger
       ),
     )