Add logger module and custom logger implementation

ConsoleLoggerService is based on the default Nest LoggerService, but adds the ability to give context about the function that is logging something. It also removes the `[Nest]` string and the PID at the beginning of each log line.

NestConsoleLoggerService is a wrapper around ConsoleLoggerService and makes it possible to use our implementation as a default Nest LoggerService

Signed-off-by: David Mehren <git@herrmehren.de>

src/logger/console-logger.service.ts

@@ -0,0 +1,119 @@
+import { Injectable, Optional, Scope } from '@nestjs/common';
+import { isObject } from '@nestjs/common/utils/shared.utils';
+import * as clc from 'cli-color';
+
+@Injectable({ scope: Scope.TRANSIENT })
+export class ConsoleLoggerService {
+  private classContext;
+  private lastTimestamp: number;
+
+  constructor(@Optional() context?: string) {
+    this.classContext = context;
+  }
+
+  setContext(context: string) {
+    this.classContext = context;
+  }
+
+  error(message: any, trace = '', functionContext?: string) {
+    this.printMessage(
+      message,
+      clc.red,
+      this.makeContextString(functionContext),
+      false,
+    );
+    this.printStackTrace(trace);
+  }
+
+  log(message: any, functionContext?: string) {
+    this.printMessage(
+      message,
+      clc.green,
+      this.makeContextString(functionContext),
+      false,
+    );
+  }
+
+  warn(message: any, functionContext?: string) {
+    this.printMessage(
+      message,
+      clc.yellow,
+      this.makeContextString(functionContext),
+      false,
+    );
+  }
+
+  debug(message: any, functionContext?: string) {
+    this.printMessage(
+      message,
+      clc.magentaBright,
+      this.makeContextString(functionContext),
+      false,
+    );
+  }
+
+  verbose(message: any, functionContext?: string) {
+    this.printMessage(
+      message,
+      clc.cyanBright,
+      this.makeContextString(functionContext),
+      false,
+    );
+  }
+
+  private makeContextString(functionContext) {
+    let context = this.classContext;
+    if (functionContext) {
+      context += '.' + functionContext + '()';
+    }
+    return context;
+  }
+
+  private printMessage(
+    message: any,
+    color: (message: string) => string,
+    context = '',
+    isTimeDiffEnabled?: boolean,
+  ) {
+    const output = isObject(message)
+      ? `${color('Object:')}\n${JSON.stringify(message, null, 2)}\n`
+      : color(message);
+
+    const localeStringOptions = {
+      year: 'numeric',
+      hour: 'numeric',
+      minute: 'numeric',
+      second: 'numeric',
+      day: '2-digit',
+      month: '2-digit',
+    };
+    //TODO make timestamp optional
+    const timestamp = new Date(Date.now()).toLocaleString(
+      undefined,
+      localeStringOptions,
+    );
+
+    const contextMessage = context ? clc.blue(`[${context}] `) : '';
+    const timestampDiff = this.updateAndGetTimestampDiff(isTimeDiffEnabled);
+
+    process.stdout.write(
+      `${timestamp} ${contextMessage}${output}${timestampDiff}\n`,
+    );
+  }
+
+  private updateAndGetTimestampDiff(isTimeDiffEnabled?: boolean): string {
+    const includeTimestamp = this.lastTimestamp && isTimeDiffEnabled;
+    const result = includeTimestamp
+      ? clc.yellow(` +${Date.now() - this.lastTimestamp}ms`)
+      : '';
+    this.lastTimestamp = Date.now();
+    return result;
+  }
+
+  private printStackTrace(trace: string) {
+    if (!trace) {
+      return;
+    }
+    process.stdout.write(`${trace}\n`);
+  }
+}

src/logger/logger.module.ts

@@ -0,0 +1,9 @@
+import { Module } from '@nestjs/common';
+import { ConsoleLoggerService } from './console-logger.service';
+import { NestConsoleLoggerService } from './nest-console-logger.service';
+
+@Module({
+  providers: [ConsoleLoggerService, NestConsoleLoggerService],
+  exports: [ConsoleLoggerService, NestConsoleLoggerService],
+})
+export class LoggerModule {}

src/logger/nest-console-logger.service.ts

@@ -0,0 +1,33 @@
+import { Injectable, LoggerService } from '@nestjs/common';
+import { ConsoleLoggerService } from './console-logger.service';
+
+Injectable();
+
+export class NestConsoleLoggerService implements LoggerService {
+  private consoleLoggerService = new ConsoleLoggerService();
+
+  debug(message: any, context?: string): any {
+    this.consoleLoggerService.setContext(context);
+    this.consoleLoggerService.debug(message);
+  }
+
+  error(message: any, trace?: string, context?: string): any {
+    this.consoleLoggerService.setContext(context);
+    this.consoleLoggerService.error(message);
+  }
+
+  log(message: any, context?: string): any {
+    this.consoleLoggerService.setContext(context);
+    this.consoleLoggerService.log(message);
+  }
+
+  verbose(message: any, context?: string): any {
+    this.consoleLoggerService.setContext(context);
+    this.consoleLoggerService.verbose(message);
+  }
+
+  warn(message: any, context?: string): any {
+    this.consoleLoggerService.setContext(context);
+    this.consoleLoggerService.warn(message);
+  }
+}