LoggerBootstrap

Bootstraps Winston logging services and middleware for your Node.js app. Using Winston (the sort of defacto standard for logging in Node), creates some sane defaults for logging using simple environment variables.

Why?

I'm getting tired of bootstrapping logging services for every app I work on.

Here are my biggest pain points:

• Creating logging services for multiple log types and transports
• Loading in environment variables for each configuration setting, and for each logging service (lots of config!)
• Setting up logging middleware
• Inconsistent logging behavior between applications (eg. different file names, message formats, etc)

LoggerBootstrap simplifies this by:

• Creating standard logging services for app logs, error logs, and access logs
• Loading in environment variables, using a standardized naming convention
• Using sane defaults of logging config
• Providing Express middleware

Setup

Install LoggerBootstrap from npm:

npm install --save logger-bootstrap

Then bootstrap your loggers:

const LoggerBootstrap = require('logger-bootstrap');

const logService = LoggerBootstrap({
	appName: 'my-app',
	envPrefix: 'MY_APP'
});

// You now have access to a winston logger
// fully configured to write to the console, the file system,
// and Loggly (optional)
logService.logger.log('My app has a logging service!');

// You also have Express middleware 
// for access logs, and error logs
const app = require('express')();

// Set up an access log
app.use(logService.requestLogMiddleware);

// Set up a response error log (logs 500 errors)
app.use(logService.errorResponseLogMiddleware);

// Create a new Elasticsearch logger, using bootstrapped options
const myEsLogger = new winston.createLogger({
    transports: [loggerBootstrap.ElasticsearchTransport({
        indexPrefix: 'testing-logger-bootstrap2',
    })]
});

myEsLogger.info({hello: "world"});

Also see example.js for a runnable example

Environment Reference

LoggerBootstrap pulls in config from environment variables. If no environment variables are defined, sane defaults will be used instead.

Each variable is prefixed with the envPrefix passed to LoggerBootstrap.

Default environment variables (using MY_APP as an example prefix):

# All variables are optional, 
# unless otherwise noted

# Location of all log files. May be relative to cwd
MY_APP_LOG_FILE_DIR=/var/log/my-app

# Application file logs (app.log)
MY_APP_LOG_FILE_ENABLED=1
MY_APP_LOG_FILE_LEVEL=info
MY_APP_LOG_FILE_MAX_SIZE=1048576	# (10 MB)
MY_APP_LOG_FILE_MAX_FILES=10
MY_APP_LOG_FILE_TIMESTAMP=1

# Application console logs
MY_APP_LOG_CONSOLE_ENABLED=1
MY_APP_LOG_CONSOLE_LEVEL=info
MY_APP_LOG_CONSOLE_TIMESTAMP=1

# Application Elasticsearch logs
MY_APP_LOG_ELASTICSEARCH_ENABLED=0
MY_APP_LOG_ELASTICSEARCH_LEVEL=info
MY_APP_LOG_ELASTICSEARCH_INDEX=[app-name]-logs
MY_APP_LOG_ELASTICSEARCH_INDEX_SUFFIX=YYYY.MM.DD

# Request file logs (access.log)
MY_APP_REQUEST_LOG_FILE_ENABLED=1
MY_APP_REQUEST_LOG_FILE_LEVEL=info
MY_APP_REQUEST_LOG_CONSOLE_TIMESTAMP=1

# Request console logs
MY_APP_REQUEST_LOG_CONSOLE_ENABLED=1
MY_APP_REQUEST_LOG_CONSOLE_LEVEL=info
MY_APP_REQUEST_LOG_CONSOLE_TIMESTAMP=1

# Request Elasticsearch logs
MY_APP_REQUEST_LOG_ELASTICSEARCH_ENABLED=0
MY_APP_REQUEST_LOG_ELASTICSEARCH_LEVEL=info
MY_APP_REQUEST_LOG_ELASTICSEARCH_INDEX=[app-name]-requests
# A Moment.js compatible data/time pattern
# See http://momentjs.com/docs/#/displaying/format/
MY_APP_REQUEST_LOG_ELASTICSEARCH_INDEX_SUFFIX=YYYY.MM.DD


# Elasticsearch configuration
# Required only if elasticsearch is enabled
ELASTICSEARCH_HOST=
ELASTICSEARCH_PORT=
ELASTICSEARCH_USER=
ELASTICSEARCH_PASS=

# Loggly logs (disabled by default)
MY_APP_LOGGLY_ENABLED=0
MY_APP_LOGGLY_LEVEL=info
# Comma separated tags
# Note that the app name and log type (app-log or access-log) 
# are automatically tagged to every log
MY_APP_LOGGLY_TAGS=
# Log messages will be buffered for this long
# (seconds), before being sent in bulk to the Loggly API
MY_APP_LOGGLY_BUFFER_INTERVAL
# Max size of the loggly message buffer,
# After which, logs will be immediately sent to the Loggly API
MY_APP_LOGGLY_BUFFER_SIZE
# required, if loggly is enabled
MY_APP_LOGGLY_TOKEN=
# required, if loggly is enabled
MY_APP_LOGGLY_SUBDOMAIN=

LoggerBootstrap Options

LoggerBootstrap accepts the following options:

// All options are optional, 
// unless otherwise noted
LoggerBootstrap({
    // Used to determine the default log file location
    // eg. /var/log/map-app/
    // Also, added as a tag to all Loggly logs
    // (required)
	appName: 'my-app',
	
	// Environment variable prefix
	// (required)
	envPrefix: 'MY_APP',

	// Use custom environment variables.
	// Defaults to `process.env`
	env: process.env,

	// Define additional meta data to be
	// passed along with request logs
	requestLogMeta: (req, res) => ({}),

	// Define a custom request log message
	requestLogMessage: (logMeta) => '',

	// Define additional meta data to be
	// passed along with error response logs
	errorResponseLogMeta: (err, req, res) => ({}),

	// Define a custom error response log message
	errorResponseLogMessage: (logMeta) => '',
	
	// Transform data, before sending to elasticsearch
	elasticsearchTransformer: data => data

});