fix(common,core): auto flush logs after useLogger call

packages/common/interfaces/nest-application-context.interface.ts

@@ -50,7 +50,8 @@ export interface INestApplicationContext {
   close(): Promise<void>;
 
   /**
-   * Sets custom logger service
+   * Sets custom logger service.
+   * Flushes buffered logs if auto flush is on.
    * @returns {void}
    */
   useLogger(logger: LoggerService | LogLevel[] | false): void;

packages/core/nest-application-context.ts

@@ -35,6 +35,8 @@ export class NestApplicationContext implements INestApplicationContext {
   protected isInitialized = false;
   protected readonly injector = new Injector();
 
+  private shouldFlushLogsOnOverride = false;
+
   private readonly activeShutdownSignals = new Array<string>();
   private readonly moduleCompiler = new ModuleCompiler();
   private shutdownCleanupRef?: (...args: unknown[]) => unknown;
@@ -131,12 +133,23 @@ export class NestApplicationContext implements INestApplicationContext {
 
   public useLogger(logger: LoggerService | LogLevel[] | false) {
     Logger.overrideLogger(logger);
+
+    if (this.shouldFlushLogsOnOverride) {
+      this.flushLogs();
+    }
   }
 
   public flushLogs() {
     Logger.flush();
   }
 
+  /**
+   * Define that it must flush logs right after defining a custom logger.
+   */
+  public flushLogsOnOverride() {
+    this.shouldFlushLogsOnOverride = true;
+  }
+
   /**
    * Enables the usage of shutdown hooks. Will call the
    * `onApplicationShutdown` function of a provider if the

packages/core/nest-factory.ts

@@ -142,6 +142,9 @@ export class NestFactoryStatic {
     const context = this.createNestInstance<NestApplicationContext>(
       new NestApplicationContext(container, [], root),
     );
+    if (this.autoFlushLogs) {
+      context.flushLogsOnOverride();
+    }
     return context.init();
   }