Lambdas for Slack Notifications

cloudWatchAlarmsToSlack.js

const fetch = require('./fetch')

const RED = '#cd3131'
const YELLOW = '#e5e512'
const GREEN = '#05bc79'
const BLUE = '#2472c8'

exports.handler = async function(event, context) {
    // Debugging
    // console.log('event', JSON.stringify(event, null, 2))
    // console.log('context', JSON.stringify(context, null, 2))
    
    const record = event.Records[0]
    const text = record.Sns.Subject
    const color = RED
    const footer = 'https://console.aws.amazon.com/cloudwatch/home'
    const body = { attachments: [{ text, color, footer }] }

    await fetch(process.env.SLACK_WEBHOOK_URL, {
        method: 'post',
        body: JSON.stringify(body),
        headers: { 'Content-Type': 'application/json' },
    })

    context.succeed()
}

ecsNotificationToSlackWebhook.js

/*
  Want to know when ECS events happen in Slack? Try this.
  (1) Create a new Slack app with an incoming webhook, save the webhook URL
  (2) Create an SNS topic called something like ECSEvents
  (3) Create a CloudWatch Rule that publishes all ECS events to the topic
  (4) Create a Node.js Lambda that is triggered by the SNS topic
  (5) Add a WEBHOOK_URL environment variable to the Lambda with the webhook URL
  (6) Paste this code into index.js
  (7) Paste the contents of https://unpkg.com/node-fetch/lib/index.js into fetch.js
  (8) Deploy and enjoy
*/

const fetch = require('./fetch')

const RED = '#cd3131'
const YELLOW = '#e5e512'
const GREEN = '#05bc79'
const BLUE = '#2472c8'

exports.handler = async(event) => {
    for (const record of event.Records) {
        const msg = JSON.parse(record.Sns.Message)
        // console.log(JSON.stringify(msg)) // For debugging
        
        const d = msg.detail
        let title = msg['detail-type']
        let color, text, body, footer
        
        if (title === "ECS Deployment State Change") {
            const env = msg.resources ? msg.resources[0].match(/:service\/(.+)/)[1] : msg.resources[1]
            text = `[${env}] ECS ${d.eventName}`
            color = /COMPLETED/.test(d.eventName) ? GREEN : YELLOW
            
        } else if (title ===  "ECS Task State Change") {
            color = /DELETED|STOPPED/.test(d.lastStatus) ? RED :
            /RUNNING/.test(d.lastStatus) ? GREEN :
            YELLOW
            
            // Stuff to ignore to make this less noisy
            if (color === YELLOW) return
            if (/Scaling activity/.test(d.stoppedReason)) return
            
            const env = d.clusterArn.replace(/^.*\//, '') + '/' + d.group.replace(/^.*:/, '')
            const status = d.lastStatus + (d.desiredStatus !== d.lastStatus ? ` (desired: ${d.desiredStatus})` : '')
            const taskDef = d.taskDefinitionArn.replace(/^.*\//, '')
            const taskId = d.taskArn.replace(/^.*\//, '')
            text = `[${env}] ECS Task ${d.lastStatus} ${taskDef}`
            footer = `Task ID ${taskId}`
            if (d.stoppedReason) text += ' - ' + d.stoppedReason
        
        } else {
            return
        }

        body = { attachments: [{ text, color, footer }] }
        // console.log(JSON.stringify(body)) // Debugging

        await fetch(process.env.SLACK_WEBHOOK_URL, {
            method: 'post',
            body: JSON.stringify(body),
            headers: { 'Content-Type': 'application/json' },
        })
    }
};

errorLogsToSlack.js

const zlib = require('zlib')
const fetch = require('./fetch') // https://unpkg.com/node-fetch@2.6.1/lib/index.js
const { promisify } = require('util')

const gunzip = promisify(zlib.gunzip)

exports.handler = async function(input, context) {
    const data = JSON.parse((await gunzip(Buffer.from(input.awslogs.data, 'base64'))).toString('utf8'))

    const body = { attachments: data.logEvents.map(e => ({ text: e.message, footer: data.logGroup })) }
    // console.log(JSON.stringify(body)) // Debugging

    await fetch(process.env.SLACK_WEBHOOK_URL, {
        method: 'post',
        body: JSON.stringify(body),
        headers: { 'Content-Type': 'application/json' },
    })

    context.succeed()
}