index.js

'use strict';

/**
 * Bunyan Log Stream compatible with SumoLogic
 * Sends logs directly to SumoLogic via the http endpoint
 *
 * Adapted from https://github.com/helix-collective/node-sumologic
 */
const request = require( 'request' );


function safeToString( obj ) {
    try {
        return JSON.stringify( obj );
    } catch ( err ) {
        try {
            return JSON.stringify( String( obj ) );
        } catch ( err2 ) {
            return JSON.stringify( 'error serializing log line' );
        }
    }
}


const LEVEL_NAMES = {
    10: 'TRACE',
    20: 'DEBUG',
    30: 'INFO',
    40: 'WARN',
    50: 'ERROR',
    60: 'FATAL'
};
function safeRewriteLevel( obj ) {
    if ( obj.level ) {
        try {
            obj.level = LEVEL_NAMES[ obj.level ]; // eslint-disable-line no-param-reassign
        } catch ( err ) { } // eslint-disable-line
    }
}


module.exports = function SumoLogger( opts ) {
    if ( !opts || !opts.collector ) {
        throw new Error( 'SumoLogic collector key must be passed' );
    }

    const endpoint = opts.endpoint || 'https://endpoint1.collection.us2.sumologic.com/receiver/v1/http/';
    const collectorEndpoint = endpoint + opts.collector;
    const syncInterval = opts.syncInterval || 1000;
    const maxLines = opts.maxLines || 100;
    let onEnd = false;

    let rewriteLevels = true;
    if ( opts.rewriteLevels !== undefined ) {
        rewriteLevels = !!opts.rewriteLevels;
    }

    // Cache of entries we are yet to sync
    const unsynced = [];

    /**
     * `write` function required on a Bunyan log stream - https://github.com/trentm/node-bunyan#stream-type-raw
     * `record` is a bunyan log record - https://github.com/trentm/node-bunyan#log-record-fields
     */
    this.write = ( record ) => {
        if ( rewriteLevels ) {
            safeRewriteLevel( record );
        }

        unsynced.push( safeToString( record ) );
    };

    /**
     * `end` function will run the callback after the sync queue is empty
     */
    this.end = ( cb ) => {
        if ( unsynced.length === 0 ) {
            return cb( null );
        }
        onEnd = cb;
        return false;
    };

    let numBeingSent = 0;

    function syncLogsToSumo() {
        // Only one active sync at any given interval
        if ( numBeingSent > 0 ) {
            return;
        }

        // Short-circuit if there is nothing to send
        if ( unsynced.length === 0 ) {
            return;
        }

        const logLines = unsynced.slice( 0, maxLines );
        const body = logLines.join( '\n' );
        numBeingSent = logLines.length;

        // Sync logs to sumo-logic, and clear all synced data. On failure we'll retry the sync
        request( {
            method: 'POST',
            url: collectorEndpoint,
            body
        }, ( error, response ) => {
            const failed = !!error ||
                           response.status < 200 ||
                           response.status >= 400;

            if ( !failed ) {
                unsynced.splice( 0, numBeingSent );
            }

            numBeingSent = 0;

            if ( onEnd ) {
                // if we are failing to log we are not going to wait
                if ( failed ) {
                    onEnd( error );
                } else if ( unsynced.length === 0 ) {
                    onEnd( null );
                }
                onEnd = false;
            }
        } );
    }
    setInterval( syncLogsToSumo, syncInterval );
};