Google Cloud Platform Uploader

npm init -y

npm install express @google-cloud/storage multer dotenv cors

GOOGLE_CLOUD_PROJECT_ID=your-project-id
GOOGLE_CLOUD_PRIVATE_KEY_ID=your-private-key-id
GOOGLE_CLOUD_PRIVATE_KEY=your-private-key
GOOGLE_CLIENT_EMAIL=your-client-email
GOOGLE_CLIENT_ID=your-client-id
GOOGLE_CLIENT_X509_CERT_URL=your-client-cert-url
GOOGLE_CLOUD_STORAGE_BUCKET=your-bucket-name
PORT=8080

// Import required modules
const express = require("express");
const multer = require("multer");
const { Storage } = require("@google-cloud/storage");
require("dotenv").config();
const cors = require("cors");

//CORS is a mechanism that allows restricted resources on a web page to be requested from another domain outside the domain from which the first resource was served. In other words, it allows you to make requests to a server from a different domain. This is useful for web applications that are hosted on different domains, but need to communicate with each other. For example, if you have a web app hosted on a domain like example.com, and you want to make requests to a server hosted on a different domain like api.example.com, you will need to enable CORS for the API server.

// Create a new Express app
const app = express();

// Enable CORS (Cross-Origin Resource Sharing) for all routes
app.use(cors());

// Create a new Storage instance using the credentials from the environment variables
const storage = new Storage({
  projectId: process.env.GOOGLE_CLOUD_PROJECT_ID,
  credentials: {
    type: "service_account",
    project_id: process.env.GOOGLE_CLOUD_PROJECT_ID,
    private_key_id: process.env.GOOGLE_CLOUD_PRIVATE_KEY_ID,
    private_key: process.env.GOOGLE_CLOUD_PRIVATE_KEY,
    client_email: process.env.GOOGLE_CLIENT_EMAIL,
    client_id: process.env.GOOGLE_CLIENT_ID,
    auth_uri: "https://accounts.google.com/o/oauth2/auth",
    token_uri: "https://oauth2.googleapis.com/token",
    auth_provider_x509_cert_url: "https://www.googleapis.com/oauth2/v1/certs",
    client_x509_cert_url: process.env.GOOGLE_CLIENT_X509_CERT_URL,
  },
});

// Define a route to handle GET requests to the root URL
app.get("/", (req, res) => {
  // Send a response with a dynamic message including an environment variable
  res.send(`Hello, ${process.env.SOME_VAR}!`);
});

// Get the bucket object using the environment variable
const bucket = storage.bucket(process.env.GOOGLE_CLOUD_STORAGE_BUCKET);

// Create a new multer instance to handle file uploads
const upload = multer({
  // Use in-memory storage for uploaded files
  storage: multer.memoryStorage(),
  // Limit the file size to 500MB
  limits: {
    fileSize: 500 * 1024 * 1024,
  },
});

// Define a route to check if a file exists in the bucket
app.get("/check", async (req, res, next) => {
  try {
    // Get the filename from the query string
    const filename = req.query.filename;

    // If the filename is not provided, return an error response
    if (!filename) {
      return res.status(400).send("Filename parameter is missing.");
    }

    // Get a reference to the file in the bucket
    const file = bucket.file(filename);
    // Check if the file exists in the bucket
    const [exists] = await file.exists();

    // Send a response with the result of the existence check
    res.status(200).send({ exists });
  } catch (err) {
    // Pass any errors to the next middleware
    next(err);
  }
});

// Define a route to handle file uploads
app.post("/upload", upload.single("file"), async (req, res, next) => {
  try {
    // If no file was uploaded, return an error response
    if (!req.file) {
      return res.status(400).send("No file uploaded.");
    }

    // Create a reference to the file in the bucket with the same name as the uploaded file
    const blob = bucket.file(req.file.originalname);

    // Create a write stream for the file in the bucket
    const blobStream = blob.createWriteStream({
      resumable: false,
    });

    // Handle any errors that occur while writing the file to the bucket
    blobStream.on("error", (err) => {
      next(err);
    });

    // Handle the completion of the file upload
    blobStream.on("finish", async () => {
      const publicUrl = `https://storage.googleapis.com/${bucket.name}/${blob.name}`;
      res.status(200).send(`File uploaded to: ${publicUrl}`);
    });

    // Get the public URL of the uploaded
    blobStream.end(req.file.buffer);
  } catch (err) {
    next(err);
  }
});

// Define a route to handle file deletions
app.delete("/delete", async (req, res, next) => {
  try {
    const filename = req.query.filename;

    // If the filename is not provided, return an error response
    if (!filename) {
      return res.status(400).send("Filename parameter is missing.");
    }

    // Get a reference to the file in the bucket
    const file = bucket.file(filename);
    // Delete the file from the bucket
    await file.delete();

    // Send a response with a success message
    res.status(200).send({ message: "File deleted successfully." });
  } catch (err) {
    next(err);
  }
});

// Define a route to handle file downloads
const PORT = process.env.PORT || 8080;

// Start the server
app.listen(PORT, () => {
  console.log(`Server listening on port ${PORT}.`);
});

node app.js