Firebase image optimizing in typescript

index.ts

import * as functions from 'firebase-functions';
import * as admin from 'firebase-admin';
import * as fs from 'fs';
import * as path from 'path';
import * as os from 'os';
import mkdirpPromise from 'mkdirp-promise';
import {spawn} from 'promisify-child-process';
import {ObjectMetadata} from "firebase-functions/lib/providers/storage";

admin.initializeApp();
const storage = admin.storage();

export const optimizeImage = functions.storage.object().onFinalize((object: ObjectMetadata) => {
    if (!object.name) {
        console.warn(`'${object.id}' has invalid name`);
        return null;
    }
    if (!object.contentType || !object.contentType.startsWith('image/')) {
        console.info(`'${object.name}' is not an image`);
        return null;
    }
    const bucket = storage.bucket(object.bucket);
    const originalFile = bucket.file(object.name);
    const tempFilePath = path.join(os.tmpdir(), object.name);
    const tempFolderPath = path.dirname(tempFilePath);
    let metadata: any = null;
    return originalFile.getMetadata()
        .then((data: any) => {
            if (Array.isArray(data) && data.length > 0 && data[0].metadata) {
                metadata = data[0].metadata;
                if (!metadata.optimized) {
                    return Promise.resolve();
                } else {
                    return Promise.reject('Image has been already optimized');
                }
            } else {
                return Promise.reject('Invalid metadata response');
            }
        })
        .then(() => mkdirpPromise(tempFolderPath))
        .then(() => originalFile.download({
            destination: tempFilePath
        }))
        .then(() => {
            console.log(`Original file downloaded to ${tempFilePath}`);
            return spawn('convert', [
                tempFilePath,
                '-strip',
                '-sampling-factor', '4:2:0',
                '-interlace', 'Plane',
                '-quality', '85',
                tempFilePath
            ]);
        })
        .then(() => {
            console.log(`Optimized image converted at ${tempFilePath}`);
            return bucket.upload(tempFilePath, {
                destination: originalFile,
                metadata: {
                    metadata: {
                        ...metadata,
                        optimized: true
                    }
                }
            });
        })
        .then(() => {
            console.log(`Optimized image uploaded at ${originalFile.name}`);
            fs.unlinkSync(tempFilePath);
        })
        .catch(error => {
            console.error(error)
        });
});

package.json

{
  "name": "functions",
  "scripts": {
    "lint": "tslint --project tsconfig.json",
    "build": "tsc",
    "serve": "npm run build && firebase serve --only functions",
    "shell": "npm run build && firebase functions:shell",
    "start": "npm run shell",
    "deploy": "firebase deploy --only functions",
    "logs": "firebase functions:log"
  },
  "main": "lib/index.js",
  "dependencies": {
    "@types/mkdirp-promise": "^5.0.0",
    "firebase-admin": "~7.0.0",
    "firebase-functions": "^2.2.0",
    "mkdirp-promise": "^5.0.1",
    "promisify-child-process": "^3.1.0"
  },
  "devDependencies": {
    "tslint": "^5.12.0",
    "typescript": "^3.2.2"
  },
  "private": true
}

tsconfig.json

{
  "compilerOptions": {
    "module": "commonjs",
    "noImplicitReturns": true,
    "noUnusedLocals": true,
    "outDir": "lib",
    "sourceMap": true,
    "strict": true,
    "target": "es2015",
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true
  },
  "compileOnSave": true,
  "include": [
    "src"
  ]
}

Awesome job! But how do i use it with"engines": { "node": "10" } ? It keeps getting timeout.