1. 业务场景

AWS Lambda 的日志中会打印awsRequestId, 过该 id 可以获取一次调用的相关执行日志进而帮助开发者查找问题.

虽然 Nodejs 中console对象写日志 Lambda 运行时会自动加上awsRequestId, 但是如果其他基于标准输出写的日志的工具运行时是无法加上awsRequestId的, 比如 Nestjs 中的Logger.

本文介绍一个代码片段提供一个自定义的 Logger, 可以记录awsRequestId.

2. 代码片段

/* eslint-disable @typescript-eslint/no-explicit-any */
import { ConsoleLogger, ConsoleLoggerOptions } from "@nestjs/common";
import { AsyncLocalStorage } from "async_hooks";
import { Handler } from "aws-lambda";

export class AWSLogger extends ConsoleLogger {
  private storage: AsyncLocalStorage<string>;

  constructor(
    storage: AsyncLocalStorage<string>,
    context?: string,
    options?: ConsoleLoggerOptions
  ) {
    super(context, options);
    this.storage = storage;
  }

  private getRequestId() {
    return this.storage.getStore();
  }

  private getLogParams(message: any, ...optionalParams: any[]) {
    const requestId = this.getRequestId();
    return requestId
      ? {
          content: `RequestId: ${requestId} | ${message}`,
          params: optionalParams,
        }
      : { content: message, params: optionalParams };
  }

  /**
   * Write a 'log' level log.
   */
  log(message: any, ...optionalParams: any[]) {
    const { content, params } = this.getLogParams(message, ...optionalParams);
    super.log(content, ...params);
  }

  /**
   * Write an 'error' level log.
   */
  error(message: any, ...optionalParams: any[]) {
    const { content, params } = this.getLogParams(message, ...optionalParams);
    super.error(content, ...params);
  }

  /**
   * Write a 'warn' level log.
   */
  warn(message: any, ...optionalParams: any[]) {
    const { content, params } = this.getLogParams(message, ...optionalParams);
    super.warn(content, ...params);
  }

  /**
   * Write a 'debug' level log.
   */
  debug(message: any, ...optionalParams: any[]) {
    const { content, params } = this.getLogParams(message, ...optionalParams);
    super.debug(content, ...params);
  }

  /**
   * Write a 'verbose' level log.
   */
  verbose(message: any, ...optionalParams: any[]) {
    const { content, params } = this.getLogParams(message, ...optionalParams);
    super.verbose(content, ...params);
  }
}

class AwsRequestIdHelper {
  private storage: AsyncLocalStorage<string>;
  private logger: AWSLogger;
  constructor() {
    this.storage = new AsyncLocalStorage<string>();
    this.logger = new AWSLogger(this.storage);
  }

  getRequestId(): string {
    return this.storage.getStore();
  }

  wrapHandler(handler: Handler, logEvent = false): Handler {
    return async (event, context, callback?) => {
      return await this.storage.run(context.awsRequestId, () => {
        if (logEvent) this.logger.log(`Event: ${JSON.stringify(event)}`);
        return handler(event, context, callback);
      });
    };
  }

  getLogger(context?: string, options?: ConsoleLoggerOptions) {
    return new AWSLogger(this.storage, context, options);
  }
}

export const awsRequestIdHelper = new AwsRequestIdHelper();

使用方法:

通过导出对象awsRequestIdHelper的wrapHandler封装已经定义好的 Lambda Handler 函数
通过导出对象awsRequestIdHelper的getLogger获得一个 Nest Logger 实例写日志,

3. 使用技巧

替换 Nest 默认Logger

无侵入的替换掉默认 Logger,让已经使用默认 Logger 写的日志都带上awsRequestId

1
2
3

const app = await NestFactory.create(AppModule, {
  logger: awsRequestIdHelper.getLogger(),
});

如此替换后, 以下写法的日志均可以带awsRequestId

import { Logger } from "@nestjs/common";
import { awsRequestIdHelper } from "xxxx";

const log = awsRequestIdHelper.getLogger("DebugLog");
log.log("log comes from custom name logger");
Logger.log("log comes from the nest default logger");

Nest 拦截器(中间件)中使用自定义的AWSLogger记录请求响应日志

import {
  Injectable,
  NestInterceptor,
  ExecutionContext,
  CallHandler,
  Logger,
  HttpException,
} from "@nestjs/common";
import { Observable, throwError } from "rxjs";
import { catchError, tap } from "rxjs/operators";
import { awsRequestIdHelper } from "./lib";

@Injectable()
export class LoggingInterceptor implements NestInterceptor {
  private readonly logger = new Logger(LoggingInterceptor.name);

  intercept = (
    context: ExecutionContext,
    next: CallHandler
  ): Observable<any> => {
    const request = context.switchToHttp().getRequest();
    const response = context.switchToHttp().getResponse();
    const { method, url, params, query } = request;
    const requestId = awsRequestIdHelper.getRequestId();

    this.logger.log(
      `IN ${requestId} ${method} ${url} ${context.getClass().name} ${
        context.getHandler().name
      } ${JSON.stringify(params)} ${JSON.stringify(query)}`
    );
    const now = Date.now();
    return next.handle().pipe(
      tap(() =>
        this.logger.log(
          `OUT ${requestId} ${Date.now() - now}ms ${response.statusCode}`
        )
      ),
      catchError((err) => {
        const code = err.getStatus ? err.getStatus() : err.status || "10000";
        this.logger.error(
          `OUT ${requestId} ${Date.now() - now}ms ${
            response.statusCode
          } ${code} '${err.message}'`
        );
        return throwError(() => err);
      })
    );
  };
}

注意:

15 行, 虽然这里用的 Nest 默认 Logger 但是通过在NestFactory.create修改默认logger属性为自定义 Logger 让中间件可以打印awsReqeustId这就是无侵入的好处.

日志效果如下:

[Nest] 8  - 06/07/2023, 4:12:08 AM     LOG [LoggingInterceptor] 6686f59f-ff0a-4b0c-a49b-a978db74cdd5 IN 6686f59f-ff0a-4b0c-a49b-a978db74cdd5 GET /nestlog AppController nestlog
{}

{}

[Nest] 8  - 06/07/2023, 4:12:08 AM     LOG [LoggingInterceptor] 6686f59f-ff0a-4b0c-a49b-a978db74cdd5 OUT 6686f59f-ff0a-4b0c-a49b-a978db74cdd5 3ms 200

Jimmy's Blog

AWS Lambda 日志优化

1. 业务场景

2. 代码片段

3. 使用技巧