Simple status page generation using Pingdom and AWS Lambda

.js

const fetch = require("node-fetch")
const fs = require("fs")
const PINGDOM_API_KEY = process.env.PINGDOM_API_KEY
const AWS = require('aws-sdk')
const s3 = new AWS.S3({signatureVersion: 'v4'})

const checksConfig = [
    {
        id: 123,
        title: 'event'
    },
    {
        id: 456,
        title: 'city'
    }
]

const monthNames = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];

exports.handler = async (event) => {
    const now = new Date();
    let render = template.replace('%update_timestamp%', now.toISOString())
    let days = new Array(30)

    // Always display the last 30 days
    days = days.fill(0).map((day, index) => {
        return new Date(now - index * 86400000)
    }).reverse().map(day => {
        return {
            timestamp: Math.round(day.getTime() / 1000),
            text: monthNames[day.getMonth()] + ' ' + day.getDate()
        }
    })

    // Proper day/month labels for the charts
    render = render.replace('%day_labels%', JSON.stringify(days.map(d => d.text)))

    // Get actual data from Pingdom
    let data = await fetch(`https://api.pingdom.com/api/3.1/checks`, {headers: {'Authorization': `Bearer ${PINGDOM_API_KEY}`}})
    let checksOverview = await data.json()

    // Go check by check and update current status and current value
    checksOverview.checks.forEach(checkData => {
        let config = checksConfig.find(config => config.id == checkData.id)
        if (config) {
            render = render.replace(`%${config.title}_status%`, ucWords(checkData.status))
            render = render.replace(`%${config.title}_current_value%`, checkData.lastresponsetime)
        }
    })

    // Normalize Pingdom data
    for (let index = 0; index < checksConfig.length; index++) {
        let data = await fetch(`https://api.pingdom.com/api/3.1/summary.performance/${checksConfig[index].id}?includeuptime=true&resolution=day&from=${monthAgoTimestamp}`, {headers: {'Authorization': `Bearer ${PINGDOM_API_KEY}`}})
        let daysData = await data.json()

        let totalUptime = 0
        let totalDowntime = 0

        daysData.summary.days.forEach(dayData => {
            totalUptime = totalUptime + dayData.uptime
            totalDowntime = totalDowntime + dayData.downtime
        })

        // Pingdom returned 30 periods with uptime value for each one, let's get a total
        let uptime = ((totalUptime / (totalDowntime + totalUptime)) * 100).toFixed(4)
        
        // Pingdom returned 30 average latency values, let's get one
        let average = Math.round((daysData.summary.days.reduce((sum, day) => { return sum + day.avgresponse; }, 0)) / daysData.summary.days.length);

        let chartData = days.map(day => {
            let timeMatch = daysData.summary.days.find((data, i) => {
                if (i == daysData.summary.days.length - 1) return day.timestamp >= data.starttime

                let endTime = daysData.summary.days[i+1].starttime - 1;
                return day.timestamp >= data.starttime && day.timestamp < endTime;
            })

            if (! timeMatch) return 0

            return timeMatch.avgresponse
        })

        // Finally, let's put everything in the resulting HTML
        render = render.replace(`%${checksConfig[index].title}_uptime%`, uptime)
        render = render.replace(`%${checksConfig[index].title}_average%`, average)
        render = render.replace(`%${checksConfig[index].title}_chart_data%`, JSON.stringify(chartData))
    }

    // Ready to upload the result
    await s3.putObject({
        Body: render,
        Bucket: process.env.DESTINATION_BUCKET,
        Key: "index.html",
        CacheControl: "no-store",
        ContentType: "text/html"
    }).promise();
};