warmup-function.js

const functions = require('firebase-functions');
const rp = require('request-promise');
const projectId = process.env.GCP_PROJECT;
const region = 'us-central1';

// GCF の List API を利用するためのサービスアカウント
// service account をリポジトリに含めたくない場合は下記のように機密データを取得する
// 設定方法: https://github.com/firebase/firebase-tools/issues/406#issuecomment-353017349
const serviceAccount = functions.config().list.cert;

// callable functionを呼ぶために使用する
const firebase = require('firebase');
firebase.initializeApp({
    projectId: process.env.GCP_PROJECT
})

async function getAccessToken() {
    const { google } = require('googleapis');
    // ref: https://developers.google.com/identity/protocols/googlescopes
    const scopes = ['https://www.googleapis.com/auth/cloudfunctions', 'https://www.googleapis.com/auth/cloud-platform'];
    const jwtClient = new google.auth.JWT(
        serviceAccount.client_email,
        undefined,
        serviceAccount.private_key,
        scopes,
        undefined
    );
    const authorization = await jwtClient.authorize();
    return authorization.access_token;
}

async function listFunction() {
    try {
        const accessToken = await getAccessToken();
        const endpoint = `https://cloudfunctions.googleapis.com/v1/projects/${projectId}/locations/${region}/functions`;
        const option = {
            uri: endpoint,
            method: 'GET',
            headers: {
                Authorization: `Bearer ${accessToken}`
            },
            qs: {
                pageSize: 100
            },
            json: true
        };

        // ref: https://cloud.google.com/functions/docs/reference/rest/v1/projects.locations.functions/list
        const res = await rp.get(option);

        return res.functions;
    } catch (err) {
        console.log(`error occurred when listing function: ${JSON.stringify(err)}`);
        return err;
    }
}

async function callHttpFunctions(urls){
    for (const url of urls){
        const option = {
            uri: url,
            method: "POST",
            body:{
    
            },
            json: true
        };

        const res = await rp(option);
        console.log(`function: ${url} is called.`)
    }
}

async function callCallableFunctions(funcNames){
    for(funcName of funcNames){
        try{
            await firebase.functions().httpsCallable(funcName)()
            console.log(`function: ${funcName} called.`)
        }catch(err){
            console.log(`error: ${JSON.stringify(err)}`);
        }
    }
}

exports.WarmupFunctions = functions
                            .pubsub
                            .topic("WarmupFunctions")
                            .onPublish(async (msg)=>{
    const urls = new Array();
    const callableFuncNames = new Array();

    const funcs = await listFunction();
    funcs.forEach(func => {
        if(!func.httpsTrigger){
            console.log(`function: ${func.name} is not https function`)
            return
        }
        const url = func.httpsTrigger.url;
        if(func.labels["deployment-callable"] === "true" ){
            callableFuncNames.push(url.split('/').slice(-1)[0]);
        }else {
            urls.push(url);
        }
        console.log(`function: ${func.name} is target`);
    })

    await callHttpFunctions(urls);
    await callCallableFunctions(callableFuncNames);
    console.log(`all functions are waked up. httpFuncs: ${urls.length}, CallableFuncs: ${callableFuncNames.length}`);
})


// 以下は動作確認用の関数

// 通常のHTTP関数
exports.HttpsFunction = functions.https.onRequest((req, res)=>{
    console.log(`req.body: ${req.body}`)
    return res.status(200).json({
        message: "OK",
        body: req.body
    })
})

// Callable関数
exports.CallableFunction = functions.https.onCall((data, context)=>{

    // uncomment in production use
    // if(!context.auth){
    //     throw new functions.https.HttpsError('unauthenticated', 'The function must be called while authenticated.');
    // }

    console.log(`function called. data: ${data}, uid: ${context.auth}`)

    return {
        message: "OK",
        data: data,
        ctx: context
    }
})

// バックグラウンド関数(pubsub トリガー)
exports.BackgroundFunction = functions.pubsub.topic("PubsubSample").onPublish(async (msg)=>{
    console.log(msg)
    return msg
})