Logish

• Node Version Greater Than or Equal To node 16

Logish is designed to be lightweight, simple and configurable.

Logish is an EventEmitter logging object that triggers a LogEvent on an entry, allowing for customized handling. Designed with LogEvent in mind, the intention was to allow developers to hook into the event to route log messages to a centralized location (such as a database) or specifically route error and fatal log events to monitoring or alerting services such as Slack, Discord, or PagerDuty.

I'm an experienced developer, with DevOps and Operations SRE experience. The purpose of this project is to create a logging system that maintains small log files in a pod (or absolutly no logs in serverless functions), intended to be configured and developed in an app for centralized logging AND app debugging. Thinking of datadog, elastic, cloudwatch or other implementations.

This should be designed through the log.on() log event EventEmitter and a Logish production configuration. Examples and documentation to come. Any Logish speed improvements are welcome.

npm i logish

Default Configuration

This configuration represents the complete default Logish configuration.

const defaultLogishConfig = {
    level : 'trace',
    performanceTime : true,
    controllers : [
        {
            name: 'console',
            active: true,
            displayOnlyEnvNamespace: false,
            displayLevels : ['trace', 'debug', 'info', 'warn', 'error', 'fatal'],
            format : '%datetime %level %namespace %entry %performance',
            useColor: true,
            colors : {
                trace   : '\x1b[32m',    debug   : '\x1b[36m',
                info    : '\x1b[37m',    warn    : '\x1b[33m',
                error   : '\x1b[35m',    fatal   : '\x1b[31m',
                reset   : '\x1b[0m'
            }
        },
        {
            name: 'file',
            active: true,
            files: [
                {
                    title: 'application',
                    active : true,
                    writeLevels: ['info', 'warn'],
                    format : '[%datetime %level] %namespace %host - %entry %performance',
                    filename: 'logs/app.log',   
                    maxsize_in_mb: 2,
                    backups_kept: 2, 
                    gzip_backups : false
                },
                {
                    title: 'errors',
                    active : true,
                    writeLevels: ['error', 'fatal'],
                    format : '[%datetime %level] %namespace %host - %entry %performance',
                    filename: 'logs/errors.log',   
                    maxsize_in_mb: 2,
                    backups_kept: 2, 
                    gzip_backups : false
                },
                {
                    title: 'development',
                    active : true,
                    writeLevels: ['trace', 'debug'],
                    format : '[%datetime %level] %namespace %host - %entry %performance',
                    filename: 'logs/dev.log',   
                    maxsize_in_mb: 2,
                    backups_kept: 2, 
                    gzip_backups : false
                }
            ]
        }
    ]
}

Basic Example

Register an event function to execute special instructions on every log entry.

// import ES6
import { Logish } from 'logish'

// load Logish object custom config values.
const log = new Logish(logishConfig)

// or use all defaults by passing no args
const logish = new Logish()

// set namespace for module
log.setNamespace('mod:index')

// Register a listener - listens for and triggers on a log event.
log.on('LogEvent', (logEntry) => {
    
    // send this type of logEntry to discord
    if (logEntry.level === 'FATAL' || logEntry.level === 'ERROR') {
        // send to Discord   
    }

    // send to MongoDB

    console.dir(logEntry)
    // output
    //   logEntry =  {
    //   level: 'debug',
    //   envVars: undefined,
    //   hostname: 'A074709-B957',
    //   message: 'this is the log message',
    //   namespace: 'example:index',
    //   datetime: { timestamp: 1660130422813, dateString: '2022-08-10 11:20:22' },
    //   performance: '0.28(ms)',
    //   entries: [
    //     {
    //       console: '2022-08-10 11:20:22 DEBUG example:index this is the log message 1.18(ms)'
    //     },
    //     {
    //       file_development: '[2022-08-10 11:20:22 DEBUG] A074709-B957 example:index | this is the log message 1.18(ms)\n'
    //     }
    //   ],
    //   data: undefined
}
})

const errorMsg = 'Something bad happened'
const sendThisToo = { byte: 1000000, kilobyte: 1000, megabyte: 1}

// Send multiple arguments, including a callback function.
log.error ('Blowup message', errorMsg, sendThisToo, (logEntry) => {
    console.log ('Inside a callback - who knows why?')
})

// Send a simple info() log entry.
log.trace('constructor()')
log.debug('connStr', connectionString)
log.info('Mongoose connected to MongoDB successfully. Nice job!')
log.error('MongoDB connection failed!', errorObject)
log.trace('END constructor()') 
// output will show time difference between trace calls IF "performanceTime : true"

LOGISH Process Variables

Run with command line environment variables.

LOGISH=index,mod:* node index.js

Launch with environment variables and set 'displayOnlyEnvNamespace: true' in the configuration to only log specific entries to console.

This example will log all 'index' namespace entries, and all namespaces with mod:*.

file1.js log.setNamespace('mod:file1')
file2.js log.setNamespace('mod:file2')

Levels

Introducing standard logging levels, but not necessarily limited to. Give me a reason to extend this...

• TRACE - Intended for code tracing, not stack tracing. (function start & function end as an example)
• DEBUG - Always need to examine values.
• INFO - Standard entry.
• WARN - Something is up, but not going to interupt flow.
• ERROR - Something happend and it will most likly screw something else up.
• FATAL - Something happened, and we need to alert the admins and shut down.

Public Methods

• getLevel()
• setLevel(value)
• getNamespace()
• setNamespace(value)
• getConfig()
• setConfig(value)
• getStats()

Contributing

Always welcome people willing to contribute. Please read the Open Source Guide. There is so much to be contributed to any project and should you choose to controbute to this project, that would be amazing. We do adhere to a (code of condeuct) and we do implement a workflow process.