A nodejs logger for AWS Lambda

• Writes logs to stdout/stderr using console.debug|info|warn|error
• Logs in JSON format (supports both pretty-printed and compact formats)
• Supports log levels: DEBUG, INFO, WARN, ERROR and OFF
• Defaults to log level INFO
• Built using typescript and includes types

Basic example:

import { APIGatewayEvent } from 'aws-lambda';
import { log, LogLevels } from '@tiqqe/lambda-logger';

export const healthCheck = async (event: APIGatewayEvent) => {
  // A standard INFO log message
  log.info('My message');
};

  // Output
  {
    "timestamp": "2020-03-26T14:36:07.345Z",
    "logLevel": "INFO",
    "message": "My message"
  }

Log Levels

The default log level is INFO log.level = LogLevels.INFO;. To show debug messages you need to explicitly set the log.level to DEBUG like this:

// Set loglevel
log.logLevel = LogLevels.DEBUG;
// Write debug log
log.debug('Debugging stuff');

{
  "timestamp": "2020-03-26T14:36:07.345Z",
  "logLevel": "DEBUG",
  "message": "Debugging stuff"
}

Logging extra data

You can add any number of extra properties to the object when logging, like this:

// Write info log
log.info({ message: 'Message', myProp: 'hello', myNestedProp: { subProp: 'something' } });

{
  "timestamp": "2020-03-26T14:36:07.345Z",
  "logLevel": "INFO",
  "message": "Message",
  "myProp": "hello",
  "myNestedProp": {
    "subProp": "something"
  }
}

Mute all logs:

log.level = LogLevels.OFF;

Set log level with environment variable

You can easily set the initial log level by setting the environment variable LOG_LEVEL. This can be useful for setting different log levels in different environments TEST|PROD etc. Use 'OFF', 'DEBUG', 'INFO', 'WARN' or 'ERROR', like this:

LOG_LEVEL: 'DEBUG'

Compact JSON output

By default, logs are pretty-printed for better readability. You can enable compact single-line output by setting the compactPrint option:

// Enable compact printing
log.init({ compactPrint: true });

log.info('My message');
// Output: {"timestamp":"2024-02-13T14:36:07.345Z","logLevel":"INFO","message":"My message"}

// Default pretty printing
log.init({ compactPrint: false });

log.info('My message');
// Output:
// {
//   "timestamp": "2024-02-13T14:36:07.345Z",
//   "logLevel": "INFO",
//   "message": "My message"
// }

Serialize BigInt

By default JSON.stringify will raise a TypeError if an object contains values of the type BigInt. By setting the supportBigIntoption to true they will be serialized to a string + "n". Example BigInt(123) -> "123n".

// Enable support for BigInt
log.init({ supportBigInt: true });

log.info({message: "BigInt supported", bigIntValue: 123n});
// Output:
// {
//   "timestamp": "2025-02-17T14:36:07.345Z",
//   "logLevel": "INFO",
//   "Message": "BigInt supported"
//   "bigIntValue": "123n"
// }



## Release process

Bump the `version` in `package.json` according to [semver](https://semver.org/spec/v2.0.0.html). If we are making a non-breaking change, compared to the last version, the new `version` would go from `0.11.0` to `0.12.0`.