2.10.1. General information about Node.js

Node.js works on hosting just as it does on a VPS or dedicated server, but with proxying HTTP traffic to the Node.js app.

Proxying HTTP traffic is necessary to protect your app from DDoS attacks and to provide you with additional features of our hosting, such as installation of a  free SSL certificate from Let's Encrypt, caching of static files, etc. Without proxying, HTTP traffic will not reach your app. If you don't need HTTP traffic, you can run your app without it — everything will work.

Two types of proxying are available:

1. By socket. When the app is launched, a socket file is created into which all HTTP traffic is proxied. The advantage of this approach is that the socket interface itself is faster than proxying by IP address; the disadvantage is that not all popular frameworks are able to start an HTTP server over a socket and accept only the parameters --host and --port in their settings. If you have the ability to run an HTTP server over a socket — we advise you to do it, if you don't — use proxying by IP address.
2. By IP address. HTTP traffic is proxied through the local IP address. This is organized as follows. We give you a unique local IP address of the form 127.*.*.*, where * is any number between 0 and 255, and the default port is 3000. You specify these values in your app's settings. Depending on your framework, these parameters may be specified in different ways, but in most cases they are the app startup parameters --host and --port. Note If you have a dedicated IP, you can directly receive any kind of traffic on any port. To use a dedicated IP, it must be explicitly specified as the second parameter in server.listen(port, ip).

The proxying type is selected in the site settings when Node.js is enabled (see below). The data for using the selected type is displayed on the Node.js settings page. They are also contained in the environment variables process.env.PORT and process.env.HOST (respectively, the socket path and an empty value when proxying over a socket, or the port and IP address when proxying over an IP address).

The order in which the request is processed:

1. Request comes to the shared server on port 80 or 443.
2. Based on the host name is redirected to the app according to the selected proxying type — to the socket of the desired site or local IP address.
3. App receives the data, processes it, and returns a response.

1. Open the "Site settings" section.
2. Select the web server Node.js, the desired version, HTTP traffic proxying type and save the changes:
3. Locate your app files in the site root directory — upload the files from a ready-made project or install using npm.
4. Add script with the start command to package.json.
5. Click "Restart" in Node.js settings.

If you need to start the app from the console and you are using proxying by IP address, you explicitly specify the IP address and port at startup:

HOST=127.*.*.* PORT=3000 node index.js

Instead of 127.*.*.* and 3000, substitute the IP address and port from the Node.js settings page.

npm — Node.js package manager. Allows you to install additional packages directly on the hosting. To use it, just connect via SSH and run the necessary commands in the site directory.

Commands:

• npm -v — view the current version of npm.
• npm install package (or npm i package) — package installation. After installation, a subdirectory node_modules will appear, where the installed module will be located.
• npm uninstall package — package deletion.

package.json — npm package configuration and management file.

Parameters:

• name (required) — app name in small Latin letters without spaces, you can use - and _ to separate words.
• version (required) — app version in x.x.x format.
• description — app description.
• dependencies — section with information about all packages used by the app.

The npm init command — creates a file from scratch. Before creating the file, all necessary data is requested. At the end you need to familiarize yourself with the contents of the future file and if everything is OK, enter yes. Note You can just press Enter for all questions, then a file with standard content will be created.

Node.js app is managed in the "Node.js settings" section.

The "App status" block:

• "App status" — current status of the Node.js service operation:
  • "Running" — service is up and running.
  • "Stopped" — is not running (e.g. because package.json is missing) or is stopped because an error occurred.
• "Start command" — presence in the package.json file of a script with the start command:
  • "Present" — script found.
  • "Missing" — script not found.
• "Force restart" — restart the service. ⚠️ Must always be pressed after any file changes.
• "Force stop" — stop the service. The button is displayed only when the app is running.

The "Main settings" block:

• Path to socket or IP address and port (depending on proxying type).
• Environment variable name with path to socket or variables with port and IP address (depending on proxying type). Note Forced to be passed to each app when it is started.
• Sample code that should be in the app to listen for site traffic.

The "App start" block — contains the command to be added to package.json to start the app (/index.js in the command is the path to the main app file, the file name can be anything):

The "Your package.json" block — shows the current contents of the package.json file from site root directory (updated when the settings page is opened or reloaded):

If syntax errors are detected in the file, the block will display the message "File contains errors". If the error message is displayed when the app is running, it means that the app was started before the error in the file appeared.

The "App logs" block — outputs real-time app logs. Includes information that the app outputs to the console during operation.

The full log is in a file of the form ~/.system/nodejs/logs/www.example.com.log, where instead of www.example.com would be the name of your site.

1. In the site root directory, create two files:
   1. Configuration file package.json:

      {
        "name": "node",
        "version": "1.0.0",
        "scripts": {
          "start": "node ./index.js"
        }
      }

   2. App file index.js:

      const HTTP = require('http');
      const WebServer = HTTP.createServer((req, res) => {
          res.statusCode = 200;
          res.setHeader('Content-Type', 'text/plain');
          res.end('Hello, World!');
      });
      WebServer.listen(process.env.HOST, process.env.PORT, () => {
          console.log(`Server is running.`);
      });

2. In Node.js settings, click "Restart".
3. Open the site in a browser — if successful, the text "Hello, World!" should be displayed.

1. Connect to the hosting via SSH.
2. Go to site root directory (use your own data in the command):

   cd example.com/www

3. Initialize npm and install express framework:

   npm init && npm i express

4. In the site root directory, create the index.js app file:

   const express = require("express");
   const app = express();
   
   app.get("/", function(request, response){
       response.end("Hello from Express!");
   });
   
   app.listen(process.env.PORT);

5. Edit the package.json file and add the run command to it:

   "scripts": {
       "start": "node ./index.js"
   }

   Observe JSON syntax when adding the command!

   The command should be added not just to the end of the file, but following the standard JSON format syntax:

   • The scripts section should not be duplicated. If it is already in the file, add the start command there.
   • There must be a comma at the end of the previous line at the same nesting level.
   • The nesting order of brackets must be correct.
6. In Node.js settings, click "Restart".
7. Open the site in a browser — if successful, the text "Hello from Express!" should be displayed.