Cloud 66 101

Deploy your Express app on Cloud 66

This guide walks you through deploying an Express.js application to your cloud using Cloud 66, from start to finish, including all the components a modern Express application is likely to use. This guide will show you how to:

  • Deploy your first Express app in just minutes
  • Explore features that support your application
  • Quickly and easily configure common components
  • Advanced configurations

Dashboard vs Toolbelt

Throughout this guide we will (wherever possible) offer you two methods for managing your application:

If you’re planning to use Toolbelt (we recommend it!), you will need to install it via your terminal.

Get going

We’ve made deploying an app as quick and easy as possible, so you should have your Express app deployed in just a few minutes. Just follow the steps below. We have a separate, standalone getting started guide which has more detail if you need it.

This guide assumes:

  • You’ve created a Cloud 66 account (we have a free tier)
  • You have an Express app ready to go in any Git repo (but Github works best) - we have a fully functional sample app if you’d like to use that to try us out.
  • An account with your favorite cloud provider

You can have your application set up in 4 simple steps.

  1. Connect your Git(hub) repo. We ask for read-only access our integration makes connecting quick and easy.
  2. We’ll analyze your app. We’ll scan your app and suggest an optimal configuration. You can adjust as needed
  3. Add a cloud provider. Connect us to your preferred cloud provider, or use one of our free credit offers.
  4. Deploy your app!

Writing a Dockerfile for your application

Dockerfiles can look intimidating at first, but a basic Dockerfile like the example below will accommodate most applications.

# Most Express apps use Node as their base
FROM node:20

# Set your Node environment

# Set /app as the working directory within the container

# Add useful packages to the container
RUN apt-get update -y \
&& apt-get upgrade -y \
&& apt-get install curl zip libvips-dev libvips-tools -y \
&& rm -rf /var/lib/apt

# Copy your package.json to the container
COPY package.json package-lock.json*

# Install your app dependencies
RUN npm ci

# Copy your application code to the container
COPY . .

# Build your code
RUN npm run build

Where is the “command” instruction?

Cloud 66 uses the command that you define during your initial app setup via our web interface. By default this command overrides whatever is in the Dockerfile. Although you can omit this, and rely on the implicit command in the Dockerfile, we strongly recommended defining commands via our interface.

Adding databases

Cloud 66 caters for a wide range of database options, including:

  • Managed by Cloud 66
  • Bring your own DB (including managed services like RDS)
  • Hybrid

Our managed databases are convenient, feature-rich and very cost effective, and allow you to centralize your infrastructure management in one system. If you’d prefer an externally managed DB, we make it easy to integrate them into your app. They do tend to be more expensive, and having your DB on a completely different subnet and/or data centre can add some latency and friction to your configuration.

You can deploy a new database (or cluster of databases) for your application with a few clicks during initial setup (or, later on, in your Dashboard). We natively support:

  • MySQL
  • PostgreSQL
  • MongoDB
  • Redis
  • InfluxDB
  • ElasticSearch

Databases can be deployed as standalone instances, in clusters, or hosted on the same server as the application. When we provision a new database we will automatically generate credentials and make them available to your application as environment variables.

All databases managed by Cloud 66 have access to these features:

  • One-click replication setup
  • Managed database backups (with automated restore)
  • Multiple logical databases per database server

Connecting to a database

In an Express application, setting up a database connection typically involves the following steps:

  1. Install Database-Specific Modules: First, you need to install a module/package that's appropriate for your database. For example:

    • For MongoDB: mongoose or mongodb
    • For MySQL: mysql2 or sequelize (if you want an ORM)
    • For PostgreSQL: pg or sequelize (if you want an ORM)

    Use npm to install the desired package:

    npm install mongoose
  2. Create a Database Configuration File: It's a common practice to create a separate file (e.g., database.js) to handle the database connection. This helps keep your code organized and makes it easier to manage different configurations for development, testing, and production environments.

  3. Establish a Connection: Here's an example using Mongoose (for MongoDB). Note the code uses the MONGO_ADDRESS environment variable, which we automatically create when we spin up your Mongo instance, rather than a hardcoded address.

    // database.js
    const mongoose = require('mongoose');
    const connectDB = async () => {
        try {
            await mongoose.connect('process.env.MONGO_ADDRESS', {
                useNewUrlParser: true,
                useUnifiedTopology: true
            console.log('MongoDB connected...');
        } catch (err) {
            // Exit process with failure
    module.exports = connectDB;
  4. Integrate with Express: In your main server file (often app.js or server.js), you can then require and call this connection function:

    const express = require('express');
    const connectDB = require('./config/database');
    const app = express();
    // Connect to database
    // ... rest of your server setup ...
    const PORT = process.env.PORT || 5000;
    app.listen(PORT, () => console.log(`Server started on port ${PORT}`));

    Note that with Cloud 66 you’re not restricted to using certain ports - you can use whatever port you choose for your components.

  5. Environment Variables: For security and flexibility, it's good practice not to hardcode database credentials or connection strings. Instead, use environment variables (see the next section).

Adding environment variables

Cloud 66 analyses your application code (for example your package.json), and supporting components (like database requirements) during deployment and creates a set of environment variables to suit your requirements. You can add your own, and update the existing ones as needed.

You can do this during initial app setup by clicking the Add Environment Variables button during after your app has been analyzed. If you need to change env vars to an existing app, you can use your preferred method below:

We automatically set your NODE_ENV to 'production'

We remove stack traces in error pages by setting the NODE_ENV environment variable to production. In addition to generating less-verbose error messages, setting the variable to production caches view templates and CSS files generated from CSS extensions.

Serving static files with Express

To serve static files such as images, CSS files, and JavaScript files, use the express.static built-in middleware function in Express.

The function signature is:

express.static(root, [options])

The root argument specifies the root directory from which to serve static assets.

For example, use the following code to serve images, CSS files, and JavaScript files in a directory named public:


Now, you can load the files that are in the public directory:


To use multiple static assets directories, call the express.static middleware function multiple times:


Express looks up the files in the order in which you set the static directories with the express.static middleware function.

To create a virtual path prefix (where the path does not actually exist in the file system) for files that are served by the express.static function, specify a mount path for the static directory, as shown below:

app.use('/static', express.static('public'))

Now, you can load the files that are in the public directory from the /static path prefix.


However, the path that you provide to the express.static function is relative to the directory from where you launch your node process. If you run the express app from another directory, it’s safer to use the absolute path of the directory that you want to serve:

const path = require('path')
app.use('/static', express.static(path.join(__dirname, 'public')))

Configure WebSockets

Cloud 66 automatically provisions your servers for use with WebSockets. We open ports 8080 and 8443 (for TLS) by default on your servers to allow you to use WebSocket. To work with optimally Cloud 66, your WebSocket servers need to listen to these ports. If you’d like a quick guide to using WebSockets with Node-based applications, this one is excellent.

Run Gulp, Grunt or generic jobs

To run tasks or jobs on your application, you have several options. For shell and application commands, you can set up Application Jobs via the dashboard, or you can SSH to your server or container and run commands directly.

Persistent storage

Node-based applications run inside containers on Cloud 66, which means they are mortal and ephemeral (in other words they can disappear and be replaced by new copies). To store files persistently, you can mount volumes from your container to the host server(s).

You can mount folders with a single line in your service.yml file (What is service.yml?) with the following form: HOST_FOLDER:CONTAINER_FOLDER.

For example:

    volumes: ["/tmp/host/foo:/tmp/container/foo"]

Persistent storage for single-server apps

If your application doesn’t require multiple servers, you can use the following method. When Cloud 66 deploys your app, we automatically create folders that persist between deployments. If you need to persist files for a single server you can simply store them under $STACK_BASE/shared (you can add sub-directories as needed).

If your Express app requires that users with different roles have access to a shared file system, then the best directory to use is $STACK_BASE/shared/frontend-backend-share. This directory is preconfigured to allow secure access from both front and backend Linux users. This also allows application users to, for example, upload files via your app.

Persistent storage for multi-server apps

If your application runs across multiple application servers and requires persistent storage, one option is to use an object storage service like Amazon S3 or Google Cloud Storage. All of the major cloud storage services have Node SDKs that make integrating them into your code quite simple. This isn’t a perfect replacement for a disk mounted at server level, but it is a viable solution for a wide variety of use cases.

Allowing users to write to disk

When Cloud 66 configures your servers, we create two Linux users:

  • nginx which handles the front-end
  • cloud66-user which handles the backend

In order to bridge the (intentional) gap between these users, we place them both in the same Linux group called app_writers - this allows for use cases where a feature needs access to both frontend and backend processes

In order to make a directory writable:

  • Set the directory owner group to app_writers
  • Set file permissions 0660
  • Set directory permissions to 0770
  • The process writing to the directory should run as the nginx user

Configuring other components

Modern Express applications rely on a range of components to perform at scale. Cloud 66 supports every Express and Node component your application needs, either natively or via our powerful Deploy Hooks feature. If it can run on Ubuntu, we support it.

This guide covers the most common components, but we support many, many more. If you’re not sure, feel free to ask our support team.

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