Winston CloudWatch Transport not Creating Logs When Running on Lambda

Question

I have an expressjs App that is setup to run from within a AWS Lambda function. When I deploy this app to the lambda, the console logs for the lambda cloudwatch log show up (i.e. /aws/lambda/lambda-name), but it doesn't create a new CloudWatch LogGroup as specified in the configuration.

If I run the lambda function locally and generate logs it will create a CloudWatch Log Group for the local environment.

The Lambda Functions are connecting to an RDS instance so they are contained within a VPC.

The Lambda has been assigned the CloudWatchFullAccess policy so it should not be a permissions error.

I've looked at the Lambda logs and I'm not seeing any errors coming through related to this.

const env = process.env.NODE_ENV || 'local'
const config = require('../../config/env.json')[env]
const winston = require('winston')
const WinstonCloudwatch = require('winston-cloudwatch')
const crypto = require('crypto')

let startTime = new Date().toISOString()
const logger = winston.createLogger({
  exitOnError: false,
  level: 'info',
  transports: [
    new winston.transports.Console({
      json: true,
      colorize: true,
      level: 'info'
    }),
    new WinstonCloudwatch({
      awsAccessKeyId: config.aws.accessKeyId,
      awsSecretKey: config.aws.secretAccessKey,
      logGroupName: 'my-api-' + env,
      logStreamName: function () {
        // Spread log streams across dates as the server stays up
        let date = new Date().toISOString().split('T')[0]
        return 'my-requests-' + date + '-' +
          crypto.createHash('md5')
            .update(startTime)
            .digest('hex')
      },
      awsRegion: 'us-east-1',
      jsonMessage: true
    })
  ]
})

const winstonStream = {
  write: (message, encoding) => {
    // use the 'info' log level so the output will be picked up by both transports
    logger.info(message)
  }
}

module.exports.logger = logger
module.exports.winstonStream = winstonStream

Then within my express app.

const morgan = require('morgan')
const { winstonStream } = require('./providers/loggers')
app.use(morgan('combined', { stream: winstonStream }

James Parker James Parker · Accepted Answer · 2019-09-20T16:39:28

Confirming that the problem was related to the lambda function being in a VPC and not granted public access to the internet through Subnets, Route Tables, NAT and Internet Gateways as described within this post. https://gist.github.com/reggi/dc5f2620b7b4f515e68e46255ac042a7

Winston CloudWatch Transport not Creating Logs When Running on Lambda

2 Answers