Dynamic Log Control

bunyan.js

import Bunyan from 'bunyan'

let {LOG_FILTER, LOG_OVERRIDE, LOG_SAMPLE} = process.env

if (LOG_OVERRIDE != null) {
    let [expire, level] = LOG_OVERRIDE.split(':')
    if (level && Date.now() < expire) {
        LOG_FILTER = level
    }
}
let sample = 0, sampleRate, sampleLevel
if (LOG_SAMPLE != null) {
    [sampleRate, sampleLevel] = LOG_SAMPLE.split(':')
}

const bunyan = Bunyan.createLogger({name: 'bunyan', level: LOG_FILTER})

exports.handler = async (event, context) => {
    if (sampleRate && (sample++ % (100 / sampleRate)) == 0) {
        bunyan.level = sampleLevel
    }
    bunyan.debug('Debug message')
    return 'done'
}

debug.js

import Debug from 'debug'

let {LOG_FILTER, LOG_OVERRIDE, LOG_SAMPLE} = process.env

if (LOG_OVERRIDE != null) {
    let [expire, level] = LOG_OVERRIDE.split(':')
    if (level && Date.now() < expire) {
        LOG_FILTER = level
    }
}
let sample = 0, sampleRate, sampleLevel
if (LOG_SAMPLE != null) {
    [sampleRate, sampleLevel] = LOG_SAMPLE.split(':')
}

Debug.enable(LOG_FILTER)

exports.handler = async (event, context) => {
    if (sampleRate && (sample++ % (100 / sampleRate)) == 0) {
        debug.enable(sampleLevel)
    }
    Debug('debug')('Debug message')
    return 'done'
}

DYNAMIC_LOG_CONTROL.md

These code samples are for the blog post Dynamic logging control for serverless without redeploying at:

http://www.sensedeep.com/blog/posts/stories/dynamic-serverless-log-control.html

pino.js

import Pino from 'pino'

let {LOG_FILTER, LOG_OVERRIDE, LOG_SAMPLE} = process.env

if (LOG_OVERRIDE != null) {
    let [expire, level] = LOG_OVERRIDE.split(':')
    if (level && Date.now() < expire) {
        LOG_FILTER = level
    }
}
let sample = 0, sampleRate, sampleLevel
if (LOG_SAMPLE != null) {
    [sampleRate, sampleLevel] = LOG_SAMPLE.split(':')
}

const pino = Pino({name: 'pino', level: LOG_FILTER})

exports.handler = async (event, context) => {
    if (sampleRate && (sample++ % (100 / sampleRate)) == 0) {
        pino.level = sampleLevel
    }
    pino.debug('Debug message')
    return 'done'
}

python.py

import os
import logging
from datetime import datetime

LOG_FILTER = os.environ.get('LOG_FILTER')
LOG_OVERRIDE = os.environ.get('LOG_OVERRIDE')
LOG_SAMPLE = os.environ.get('LOG_SAMPLE')

sample = 0
sampleRate = 0
sampleLevel = None

if LOG_SAMPLE != None:
    sampleRate, sampleLevel = LOG_SAMPLE.split(':')

if LOG_OVERRIDE != None:
    when, level = LOG_OVERRIDE.split(':')
    if level and int(datetime.today().timestamp()) < int(when):
        LOG_FILTER = level

logging.basicConfig(level = int(LOG_FILTER))
log = logging.getLogger()

def lambda_handler(event, context):
    sample = sample + 1
    if sampleRate and (sample % (100 / sampleRate)) == 0:
        log.setLevel(int(sampleLevel))
        
    log.info("Hello World")
    return 'done'

senselogs.js

import SenseLogs from 'senselogs'

let log = new SenseLogs()

exports.handler = async (event, context) => {
    //  This will be emitted if LOG_FILTER contains 'debug' as a log level
    log.debug('Hello world')
    //  EMF metrics can also be dynamically controlled
    log.metrics('metrics', 'AcmeRockets/CriticalLaunchFailure', {explosion: 1})
    return 'done'
}

winston.js

import Winston from 'winston'

let {LOG_FILTER, LOG_OVERRIDE, LOG_SAMPLE} = process.env

if (LOG_OVERRIDE != null) {
    let [expire, level] = LOG_OVERRIDE.split(':')
    if (level && Date.now() < expire) {
        LOG_FILTER = level
    }
}
let sample = 0, sampleRate, sampleLevel
if (LOG_SAMPLE != null) {
    [sampleRate, sampleLevel] = LOG_SAMPLE.split(':')
}

const winston = Winston.createLogger({
    level: LOG_FILTER,
    transports: [new Winston.transports.Console()],
})

exports.handler = async (event, context) => {
    if (sampleRate && (sample++ % (100 / sampleRate)) == 0) {
        winston.transports[0].level = sampleLevel
    }
    winston.debug('Debug message')
    return 'done'
}