Winston logging wrapper

This is a simple opinionated wrapper around the logging library Winston to provide a logger that is easy to use and configure.

It accesses and inject several env variables (like runtime or package version) to each log event.

If IS_LOCAL is set to true, it will use a more human readable, colorized output format, otherwise it will use JSON on one line.

Debug logs will only be logged if the env STAGE is set to dev.

Usage

import logger from '@frytg/logger';

logger.log({
  level: 'alert',
  message: 'my log message',
  source: 'folder-a/file-b/function-c',
  data: { name: 'my-data' },
});

The logger accesses and injects several env variables to each log event (envs listed in order of priority):

host - the host name (e.g. my-function)
- from env K_REVISION - set by Knative such as Google Cloud Run
- from envAWS_LAMBDA_FUNCTION_NAME - set by AWS Lambda
- from os.hostname() - fallback
serviceName - the service name (e.g. my-service)
- from env SERVICE_NAME - set by your deployment
- from env K_SERVICE - set by Knative such as Google Cloud Run
stage - the stage (e.g. dev)
- from env STAGE - set by your deployment
- from env NODE_ENV - set by your deployment
version - the version (e.g. 1.0.0)
- from env SERVICE_VERSION - set by your deployment
- from env npm_package_version - set by your deployment in package.json
region - the region (e.g. eu-west-1)
- from env REGION - set by your deployment
- from env AWS_REGION - set by AWS Lambda
runtime - the runtime (e.g. nodejs-20.11.0)
- from process.versions.bun - set by Bun
- from process.versions.deno - set by Deno
- from env AWS_EXECUTION_ENV - set by AWS Lambda
- from process.version - fallback (usually Node.js)

Additionally these environment variables are triggering different logging formats:

IS_LOCAL - set to true to use a more human readable, colorized output format that uses multiple lines
STAGE - set to dev to enable debug logs

It is currently pre-configured with the syslog log levels from most to least severe:

{
  emerg: 0,
  alert: 1,
  crit: 2,
  error: 3,
  warning: 4,
  notice: 5,
  info: 6,
  debug: 7
}