Google App Engine Flex toggler

index.js

const moment = require("moment");
const {google} = require('googleapis');
const gae = google.appengine('v1');

const auth = new google.auth.GoogleAuth({
    scopes: ['https://www.googleapis.com/auth/appengine.admin',
            'https://www.googleapis.com/auth/cloud-platform',
            'https://www.googleapis.com/auth/cloud-platform.read-only']
});

async function scheduleGAE(pubSubEvent, context) {
    const authClient = await auth.getClient();
    const versionsResponse = await gae.apps.services.versions.list({
        auth: authClient,
        appsId: "<APP_ID>",
        servicesId: "default",
        fields: "versions(id,name,servingStatus)"
    });
    if (versionsResponse.status == 200) {
        const versions = versionsResponse.data.versions;

        // find the latest version
        const latest = versions.reduce(
            (prev, current) => prev.id > current.id ? prev : current,
            versions[0]
        );

        console.log(`Latest version is ${latest.name} with status ${latest.servingStatus}`);

        const time = moment(context.timestamp);
        const newStatus = time.hour() % 12 == 0 ? "SERVING" : "STOPPED";
        console.log(`Patching to status ${newStatus}`);
        return gae.apps.services.versions.patch({
            auth: authClient,
            appsId: "<APP_ID>",
            servicesId: "default",
            versionsId: latest.id,
            updateMask: "servingStatus",
            requestBody: {
                servingStatus: newStatus
            }
        });
    } else {
        throw new Error(`Error ${versionsResponse.statusText}: ${versionsResponse.statusText}`);
    }
}

module.exports = {
    scheduleGAE: scheduleGAE
};