GCPの料金アラートをSlackに出してみる

{
  "budgetDisplayName": "sitateru",
  "alertThresholdExceeded": 0.8,
  "costAmount": 43210,
  "costIntervalStart": "2020-08-01T07:00:00Z",
  "budgetAmount": 50000,
  "budgetAmountType": "SPECIFIED_AMOUNT",
  "currencyCode": "JPY"
}

const slack = require('slack')
const Firestore = require('@google-cloud/firestore')

// slackbotのアクセストークン
const BOT_ACCESS_TOKEN = process.env.BOT_ACCESS_TOKEN
// 投稿先slackチャンネル名
const CHANNEL = process.env.SLACK_CHANNEL
// GCPの予算ページに飛べるようにURLを入れる
const BUDGET_URL = process.env.BUDGET_URL

const collection = new Firestore({
  projectId: process.env.PROJECT_ID,
  keyFilename: process.env.KEYFILE
}).collection('billing_alert_slack')

exports.billingAlertSlack = async (pubsubEvent, context) => {
  const pubsubData = JSON.parse(Buffer.from(pubsubEvent.data, 'base64').toString())

  const postSlack = async (fields) => {
    const messageFields = Object.entries(fields).map(datum => {
      return {
        "title": datum[0],
        "value": datum[1],
        "short": true
      }
    })
    await slack.chat.postMessage({
      token: BOT_ACCESS_TOKEN,
      channel: CHANNEL,
      text: '',
      attachments:  [{
        "color": "#1a73e8",
        "title": "GCP Billing Alert",
        "title_link": BUDGET_URL,
        "fields": messageFields
      }]
    })
    return 'Slack notification sent successfully'
  }

  if(pubsubData.hasOwnProperty("alertThresholdExceeded") || pubsubData.hasOwnProperty("forecastThresholdExceeded")) {
    const ThresholdExceeded = pubsubData.hasOwnProperty("alertThresholdExceeded") ? pubsubData.alertThresholdExceeded : pubsubData.forecastThresholdExceeded
    const querySnapshot = await collection.where('budgetDisplayName', '==', pubsubData.budgetDisplayName)
      .where('ThresholdExceeded', '==', ThresholdExceeded)
      .where('budgetAmountType', '==', pubsubData.budgetAmountType)
      .get()
    if (querySnapshot.docs.length) {
      const data = querySnapshot.docs[0].data()
      if (pubsubData.costIntervalStart != data.costIntervalStart) {
        // update document
        querySnapshot.docs[0].ref.update({ costIntervalStart: pubsubData.costIntervalStart })
        // post slack
        return await postSlack(pubsubData)
      }
    } else {
      // add document
      collection.add({
        budgetDisplayName: pubsubData.budgetDisplayName,
        ThresholdExceeded: ThresholdExceeded,
        budgetAmountType: pubsubData.budgetAmountType,
        costIntervalStart: pubsubData.costIntervalStart
      })
      // post slack
      return await postSlack(pubsubData)
    }
  } else {
    return 'Slack notification was not sent'
  }
}