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      How To Set Up a Node.js Application for Production on Ubuntu 20.04


      Not using Ubuntu 20.04?


      Choose a different version or distribution.

      Introduction

      Node.js is an open-source JavaScript runtime environment for building server-side and networking applications. The platform runs on Linux, macOS, FreeBSD, and Windows. Though you can run Node.js applications at the command line, this tutorial will focus on running them as a service. This means that they will restart on reboot or failure and are safe for use in a production environment.

      In this tutorial, you will set up a production-ready Node.js environment on a single Ubuntu 20.04 server. This server will run a Node.js application managed by PM2, and provide users with secure access to the application through an Nginx reverse proxy. The Nginx server will offer HTTPS using a free certificate provided by Let’s Encrypt.

      Prerequisites

      This guide assumes that you have the following:

      When you’ve completed the prerequisites, you will have a server serving your domain’s default placeholder page at https://example.com/.

      Step 1 — Installing Node.js

      Let’s begin by installing the latest LTS release of Node.js, using the NodeSource package archives.

      First, install the NodeSource PPA in order to get access to its contents. Make sure you’re in your home directory, and use curl to retrieve the installation script for the most recent LTS version of Node.js from its archives.

      • cd ~
      • curl -sL https://deb.nodesource.com/setup_14.x -o nodesource_setup.sh

      You can inspect the contents of this script with nano or your preferred text editor:

      When you’re done inspecting the script, run it under sudo:

      • sudo bash nodesource_setup.sh

      The PPA will be added to your configuration and your local package cache will be updated automatically. After running the setup script from Nodesource, you can install the Node.js package:

      To check which version of Node.js you have installed after these initial steps, type:

      Output

      v14.4.0

      Note: When installing from the NodeSource PPA, the Node.js executable is called nodejs, rather than node.

      The nodejs package contains the nodejs binary as well as npm, a package manager for Node modules, so you don’t need to install npm separately.

      npm uses a configuration file in your home directory to keep track of updates. It will be created the first time you run npm. Execute this command to verify that npm is installed and to create the configuration file:

      Output

      6.14.5

      In order for some npm packages to work (those that require compiling code from source, for example), you will need to install the build-essential package:

      • sudo apt install build-essential

      You now have the necessary tools to work with npm packages that require compiling code from source.

      With the Node.js runtime installed, let’s move on to writing a Node.js application.

      Step 2 — Creating a Node.js Application

      Let’s write a Hello World application that returns “Hello World” to any HTTP requests. This sample application will help you get Node.js set up. You can replace it with your own application — just make sure that you modify your application to listen on the appropriate IP addresses and ports.

      First, let’s create a sample application called hello.js:

      Insert the following code into the file:

      ~/hello.js

      const http = require('http');
      
      const hostname="localhost";
      const port = 3000;
      
      const server = http.createServer((req, res) => {
        res.statusCode = 200;
        res.setHeader('Content-Type', 'text/plain');
        res.end('Hello World!n');
      });
      
      server.listen(port, hostname, () => {
        console.log(`Server running at http://${hostname}:${port}/`);
      });
      

      Save the file and exit the editor.

      This Node.js application listens on the specified address (localhost) and port (3000), and returns “Hello World!” with a 200 HTTP success code. Since we’re listening on localhost, remote clients won’t be able to connect to our application.

      To test your application, type:

      You will receive the following output:

      Output

      Server running at http://localhost:3000/

      Note: Running a Node.js application in this manner will block additional commands until the application is killed by pressing CTRL+C.

      To test the application, open another terminal session on your server, and connect to localhost with curl:

      • curl http://localhost:3000

      If you get the following output, the application is working properly and listening on the correct address and port:

      Output

      Hello World!

      If you do not get the expected output, make sure that your Node.js application is running and configured to listen on the proper address and port.

      Once you’re sure it’s working, kill the application (if you haven’t already) by pressing CTRL+C.

      Step 3 — Installing PM2

      Next let’s install PM2, a process manager for Node.js applications. PM2 makes it possible to daemonize applications so that they will run in the background as a service.

      Use npm to install the latest version of PM2 on your server:

      • sudo npm install pm2@latest -g

      The -g option tells npm to install the module globally, so that it’s available system-wide.

      Let’s first use the pm2 start command to run your application, hello.js, in the background:

      This also adds your application to PM2’s process list, which is outputted every time you start an application:

      Output

      ... [PM2] Spawning PM2 daemon with pm2_home=/home/sammy/.pm2 [PM2] PM2 Successfully daemonized [PM2] Starting /home/sammy/hello.js in fork_mode (1 instance) [PM2] Done. ┌────┬────────────────────┬──────────┬──────┬───────────┬──────────┬──────────┐ │ id │ name │ mode │ ↺ │ status │ cpu │ memory │ ├────┼────────────────────┼──────────┼──────┼───────────┼──────────┼──────────┤ │ 0 │ hello │ fork │ 0 │ online │ 0% │ 25.2mb │ └────┴────────────────────┴──────────┴──────┴───────────┴──────────┴──────────┘

      As indicated above, PM2 automatically assigns an App name (based on the filename, without the .js extension) and a PM2 id. PM2 also maintains other information, such as the PID of the process, its current status, and memory usage.

      Applications that are running under PM2 will be restarted automatically if the application crashes or is killed, but we can take an additional step to get the application to launch on system startup using the startup subcommand. This subcommand generates and configures a startup script to launch PM2 and its managed processes on server boots:

      The last line of the resulting output will include a command to run with superuser privileges in order to set PM2 to start on boot:

      Output

      [PM2] Init System found: systemd sammy [PM2] To setup the Startup Script, copy/paste the following command: sudo env PATH=$PATH:/usr/bin /usr/lib/node_modules/pm2/bin/pm2 startup systemd -u sammy --hp /home/sammy

      Run the command from the output, with your username in place of sammy:

      • sudo env PATH=$PATH:/usr/bin /usr/lib/node_modules/pm2/bin/pm2 startup systemd -u sammy --hp /home/sammy

      As an additional step, we can save the PM2 process list and corresponding environments:

      You have now created a systemd unit that runs pm2 for your user on boot. This pm2 instance, in turn, runs hello.js.

      Start the service with systemctl:

      • sudo systemctl start pm2-sammy

      If at this point you encounter an error, you may need to reboot, which you can achieve with sudo reboot.

      Check the status of the systemd unit:

      • systemctl status pm2-sammy

      For a detailed overview of systemd, please review Systemd Essentials: Working with Services, Units, and the Journal.

      In addition to those we have covered, PM2 provides many subcommands that allow you to manage or look up information about your applications.

      Stop an application with this command (specify the PM2 App name or id):

      Restart an application:

      • pm2 restart app_name_or_id

      List the applications currently managed by PM2:

      Get information about a specific application using its App name:

      The PM2 process monitor can be pulled up with the monit subcommand. This displays the application status, CPU, and memory usage:

      Note that running pm2 without any arguments will also display a help page with example usage.

      Now that your Node.js application is running and managed by PM2, let’s set up the reverse proxy.

      Step 4 — Setting Up Nginx as a Reverse Proxy Server

      Your application is running and listening on localhost, but you need to set up a way for your users to access it. We will set up the Nginx web server as a reverse proxy for this purpose.

      In the prerequisite tutorial, you set up your Nginx configuration in the /etc/nginx/sites-available/example.com file. Open this file for editing:

      • sudo nano /etc/nginx/sites-available/example.com

      Within the server block, you should have an existing location / block. Replace the contents of that block with the following configuration. If your application is set to listen on a different port, update the highlighted portion to the correct port number:

      /etc/nginx/sites-available/example.com

      server {
      ...
          location / {
              proxy_pass http://localhost:3000;
              proxy_http_version 1.1;
              proxy_set_header Upgrade $http_upgrade;
              proxy_set_header Connection 'upgrade';
              proxy_set_header Host $host;
              proxy_cache_bypass $http_upgrade;
          }
      ...
      }
      

      This configures the server to respond to requests at its root. Assuming our server is available at example.com, accessing https://example.com/ via a web browser would send the request to hello.js, listening on port 3000 at localhost.

      You can add additional location blocks to the same server block to provide access to other applications on the same server. For example, if you were also running another Node.js application on port 3001, you could add this location block to allow access to it via https://example.com/app2:

      /etc/nginx/sites-available/example.com — Optional

      server {
      ...
          location /app2 {
              proxy_pass http://localhost:3001;
              proxy_http_version 1.1;
              proxy_set_header Upgrade $http_upgrade;
              proxy_set_header Connection 'upgrade';
              proxy_set_header Host $host;
              proxy_cache_bypass $http_upgrade;
          }
      ...
      }
      

      Once you are done adding the location blocks for your applications, save the file and exit your editor.

      Make sure you didn’t introduce any syntax errors by typing:

      Restart Nginx:

      • sudo systemctl restart nginx

      Assuming that your Node.js application is running, and your application and Nginx configurations are correct, you should now be able to access your application via the Nginx reverse proxy. Try it out by accessing your server’s URL (its public IP address or domain name).

      Conclusion

      Congratulations! You now have your Node.js application running behind an Nginx reverse proxy on an Ubuntu 20.04 server. This reverse proxy setup is flexible enough to provide your users access to other applications or static web content that you want to share.



      Source link

      How To Build a Node.js Application with Docker on Ubuntu 20.04


      Introduction

      The Docker platform allows developers to package and run applications as containers. A container is an isolated process that runs on a shared operating system, offering a lighter weight alternative to virtual machines. Though containers are not new, they offer benefits — including process isolation and environment standardization — that are growing in importance as more developers use distributed application architectures.

      When building and scaling an application with Docker, the starting point is typically creating an image for your application, which you can then run in a container. The image includes your application code, libraries, configuration files, environment variables, and runtime. Using an image ensures that the environment in your container is standardized and contains only what is necessary to build and run your application.

      In this tutorial, you will create an application image for a static website that uses the Express framework and Bootstrap. You will then build a container using that image and push it to Docker Hub for future use. Finally, you will pull the stored image from your Docker Hub repository and build another container, demonstrating how you can recreate and scale your application.

      Prerequisites

      To follow this tutorial, you will need:

      Step 1 — Installing Your Application Dependencies

      To create your image, you will first need to make your application files, which you can then copy to your container. These files will include your application’s static content, code, and dependencies.

      First, create a directory for your project in your non-root user’s home directory. We will call ours node_project, but you should feel free to replace this with something else:

      Navigate to this directory:

      This will be the root directory of the project.

      Next, create a package.json file with your project’s dependencies and other identifying information. Open the file with nano or your favorite editor:

      Add the following information about the project, including its name, author, license, entrypoint, and dependencies. Be sure to replace the author information with your own name and contact details:

      ~/node_project/package.json

      {
        "name": "nodejs-image-demo",
        "version": "1.0.0",
        "description": "nodejs image demo",
        "author": "Sammy the Shark <sammy@example.com>",
        "license": "MIT",
        "main": "app.js",
        "keywords": [
          "nodejs",
          "bootstrap",
          "express"
        ],
        "dependencies": {
          "express": "^4.16.4"
        }
      }
      

      This file includes the project name, author, and license under which it is being shared. Npm recommends making your project name short and descriptive, and avoiding duplicates in the npm registry. We’ve listed the MIT license in the license field, permitting the free use and distribution of the application code.

      Additionally, the file specifies:

      • "main": The entrypoint for the application, app.js. You will create this file next.
      • "dependencies": The project dependencies — in this case, Express 4.16.4 or above.

      Though this file does not list a repository, you can add one by following these guidelines on adding a repository to your package.json file. This is a good addition if you are versioning your application.

      Save and close the file when you’ve finished making changes.

      To install your project’s dependencies, run the following command:

      This will install the packages you’ve listed in your package.json file in your project directory.

      We can now move on to building the application files.

      Step 2 — Creating the Application Files

      We will create a website that offers users information about sharks. Our application will have a main entrypoint, app.js, and a views directory that will include the project’s static assets. The landing page, index.html, will offer users some preliminary information and a link to a page with more detailed shark information, sharks.html. In the views directory, we will create both the landing page and sharks.html.

      First, open app.js in the main project directory to define the project’s routes:

      The first part of the file will create the Express application and Router objects, and define the base directory and port as constants:

      ~/node_project/app.js

      const express = require('express');
      const app = express();
      const router = express.Router();
      
      const path = __dirname + '/views/';
      const port = 8080;
      

      The require function loads the express module, which we then use to create the app and router objects. The router object will perform the routing function of the application, and as we define HTTP method routes we will add them to this object to define how our application will handle requests.

      This section of the file also sets a couple of constants, path and port:

      • path: Defines the base directory, which will be the views subdirectory within the current project directory.
      • port: Tells the app to listen on and bind to port 8080.

      Next, set the routes for the application using the router object:

      ~/node_project/app.js

      ...
      
      router.use(function (req,res,next) {
        console.log("https://www.digitalocean.com/" + req.method);
        next();
      });
      
      router.get("https://www.digitalocean.com/", function(req,res){
        res.sendFile(path + 'index.html');
      });
      
      router.get("https://www.digitalocean.com/sharks", function(req,res){
        res.sendFile(path + 'sharks.html');
      });
      

      The router.use function loads a middleware function that will log the router’s requests and pass them on to the application’s routes. These are defined in the subsequent functions, which specify that a GET request to the base project URL should return the index.html page, while a GET request to the /sharks route should return sharks.html.

      Finally, mount the router middleware and the application’s static assets and tell the app to listen on port 8080:

      ~/node_project/app.js

      ...
      
      app.use(express.static(path));
      app.use("https://www.digitalocean.com/", router);
      
      app.listen(port, function () {
        console.log('Example app listening on port 8080!')
      })
      

      The finished app.js file will look like this:

      ~/node_project/app.js

      const express = require('express');
      const app = express();
      const router = express.Router();
      
      const path = __dirname + '/views/';
      const port = 8080;
      
      router.use(function (req,res,next) {
        console.log("https://www.digitalocean.com/" + req.method);
        next();
      });
      
      router.get("https://www.digitalocean.com/", function(req,res){
        res.sendFile(path + 'index.html');
      });
      
      router.get("https://www.digitalocean.com/sharks", function(req,res){
        res.sendFile(path + 'sharks.html');
      });
      
      app.use(express.static(path));
      app.use("https://www.digitalocean.com/", router);
      
      app.listen(port, function () {
        console.log('Example app listening on port 8080!')
      })
      

      Save and close the file when you are finished.

      Next, let’s add some static content to the application. Start by creating the views directory:

      Open the landing page file, index.html:

      Add the following code to the file, which will import Boostrap and create a jumbotron component with a link to the more detailed sharks.html info page:

      ~/node_project/views/index.html

      <!DOCTYPE html>
      <html lang="en">
      
      <head>
          <title>About Sharks</title>
          <meta charset="utf-8">
          <meta name="viewport" content="width=device-width, initial-scale=1">
          <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css" integrity="sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" crossorigin="anonymous">
          <link href="https://www.digitalocean.com/css/styles.css" rel="stylesheet">
          <link href="https://fonts.googleapis.com/css?family=Merriweather:400,700" rel="stylesheet" type="text/css">
      </head>
      
      <body>
          <nav class="navbar navbar-dark bg-dark navbar-static-top navbar-expand-md">
              <div class="container">
                  <button type="button" class="navbar-toggler collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1" aria-expanded="false"> <span class="sr-only">Toggle navigation</span>
                  </button> <a class="navbar-brand" href="#">Everything Sharks</a>
                  <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
                      <ul class="nav navbar-nav mr-auto">
                          <li class="active nav-item"><a href="https://www.digitalocean.com/" class="nav-link">Home</a>
                          </li>
                          <li class="nav-item"><a href="https://www.digitalocean.com/sharks" class="nav-link">Sharks</a>
                          </li>
                      </ul>
                  </div>
              </div>
          </nav>
          <div class="jumbotron">
              <div class="container">
                  <h1>Want to Learn About Sharks?</h1>
                  <p>Are you ready to learn about sharks?</p>
                  <br>
                  <p><a class="btn btn-primary btn-lg" href="https://www.digitalocean.com/sharks" role="button">Get Shark Info</a>
                  </p>
              </div>
          </div>
          <div class="container">
              <div class="row">
                  <div class="col-lg-6">
                      <h3>Not all sharks are alike</h3>
                      <p>Though some are dangerous, sharks generally do not attack humans. Out of the 500 species known to researchers, only 30 have been known to attack humans.
                      </p>
                  </div>
                  <div class="col-lg-6">
                      <h3>Sharks are ancient</h3>
                      <p>There is evidence to suggest that sharks lived up to 400 million years ago.
                      </p>
                  </div>
              </div>
          </div>
      </body>
      
      </html>
      

      The top-level navbar here allows users to toggle between the Home and Sharks pages. In the navbar-nav subcomponent, we are using Bootstrap’s active class to indicate the current page to the user. We’ve also specified the routes to our static pages, which match the routes we defined in app.js:

      ~/node_project/views/index.html

      ...
      <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
         <ul class="nav navbar-nav mr-auto">
            <li class="active nav-item"><a href="https://www.digitalocean.com/" class="nav-link">Home</a>
            </li>
            <li class="nav-item"><a href="https://www.digitalocean.com/sharks" class="nav-link">Sharks</a>
            </li>
         </ul>
      </div>
      ...
      

      Additionally, we’ve created a link to our shark information page in our jumbotron’s button:

      ~/node_project/views/index.html

      ...
      <div class="jumbotron">
         <div class="container">
            <h1>Want to Learn About Sharks?</h1>
            <p>Are you ready to learn about sharks?</p>
            <br>
            <p><a class="btn btn-primary btn-lg" href="https://www.digitalocean.com/sharks" role="button">Get Shark Info</a>
            </p>
         </div>
      </div>
      ...
      

      There is also a link to a custom style sheet in the header:

      ~/node_project/views/index.html

      ...
      <link href="https://www.digitalocean.com/css/styles.css" rel="stylesheet">
      ...
      

      We will create this style sheet at the end of this step.

      Save and close the file when you are finished.

      With the application landing page in place, we can create our shark information page, sharks.html, which will offer interested users more information about sharks.

      Open the file:

      Add the following code, which imports Bootstrap and the custom style sheet and offers users detailed information about certain sharks:

      ~/node_project/views/sharks.html

      <!DOCTYPE html>
      <html lang="en">
      
      <head>
          <title>About Sharks</title>
          <meta charset="utf-8">
          <meta name="viewport" content="width=device-width, initial-scale=1">
          <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css" integrity="sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" crossorigin="anonymous">
          <link href="https://www.digitalocean.com/css/styles.css" rel="stylesheet">
          <link href="https://fonts.googleapis.com/css?family=Merriweather:400,700" rel="stylesheet" type="text/css">
      </head>
      <nav class="navbar navbar-dark bg-dark navbar-static-top navbar-expand-md">
          <div class="container">
              <button type="button" class="navbar-toggler collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1" aria-expanded="false"> <span class="sr-only">Toggle navigation</span>
              </button> <a class="navbar-brand" href="https://www.digitalocean.com/">Everything Sharks</a>
              <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
                  <ul class="nav navbar-nav mr-auto">
                      <li class="nav-item"><a href="https://www.digitalocean.com/" class="nav-link">Home</a>
                      </li>
                      <li class="active nav-item"><a href="https://www.digitalocean.com/sharks" class="nav-link">Sharks</a>
                      </li>
                  </ul>
              </div>
          </div>
      </nav>
      <div class="jumbotron text-center">
          <h1>Shark Info</h1>
      </div>
      <div class="container">
          <div class="row">
              <div class="col-lg-6">
                  <p>
                      <div class="caption">Some sharks are known to be dangerous to humans, though many more are not. The sawshark, for example, is not considered a threat to humans.
                      </div>
                      <img src="https://assets.digitalocean.com/articles/docker_node_image/sawshark.jpg" alt="Sawshark">
                  </p>
              </div>
              <div class="col-lg-6">
                  <p>
                      <div class="caption">Other sharks are known to be friendly and welcoming!</div>
                      <img src="https://assets.digitalocean.com/articles/docker_node_image/sammy.png" alt="Sammy the Shark">
                  </p>
              </div>
          </div>
      </div>
      
      </html>
      

      Note that in this file, we again use the active class to indicate the current page.

      Save and close the file when you are finished.

      Finally, create the custom CSS style sheet that you’ve linked to in index.html and sharks.html by first creating a css folder in the views directory:

      Open the style sheet:

      • nano views/css/styles.css

      Add the following code, which will set the desired color and font for our pages:

      ~/node_project/views/css/styles.css

      .navbar {
          margin-bottom: 0;
      }
      
      body {
          background: #020A1B;
          color: #ffffff;
          font-family: 'Merriweather', sans-serif;
      }
      
      h1,
      h2 {
          font-weight: bold;
      }
      
      p {
          font-size: 16px;
          color: #ffffff;
      }
      
      .jumbotron {
          background: #0048CD;
          color: white;
          text-align: center;
      }
      
      .jumbotron p {
          color: white;
          font-size: 26px;
      }
      
      .btn-primary {
          color: #fff;
          text-color: #000000;
          border-color: white;
          margin-bottom: 5px;
      }
      
      img,
      video,
      audio {
          margin-top: 20px;
          max-width: 80%;
      }
      
      div.caption: {
          float: left;
          clear: both;
      }
      

      In addition to setting font and color, this file also limits the size of the images by specifying a max-width of 80%. This will prevent them from taking up more room than we would like on the page.

      Save and close the file when you are finished.

      With the application files in place and the project dependencies installed, you are ready to start the application.

      If you followed the initial server setup tutorial in the prerequisites, you will have an active firewall permitting only SSH traffic. To permit traffic to port 8080 run:

      To start the application, make sure that you are in your project’s root directory:

      Start the application with node app.js:

      Navigate your browser to http://your_server_ip:8080. You will load the following landing page:

      Application Landing Page

      Click on the Get Shark Info button. The following information page will load:

      Shark Info Page

      You now have an application up and running. When you are ready, quit the server by typing CTRL+C. We can now move on to creating the Dockerfile that will allow us to recreate and scale this application as desired.

      Step 3 — Writing the Dockerfile

      Your Dockerfile specifies what will be included in your application container when it is executed. Using a Dockerfile allows you to define your container environment and avoid discrepancies with dependencies or runtime versions.

      Following these guidelines on building optimized containers, we will make our image as efficient as possible by minimizing the number of image layers and restricting the image’s function to a single purpose — recreating our application files and static content.

      In your project’s root directory, create the Dockerfile:

      Docker images are created using a succession of layered images that build on one another. Our first step will be to add the base image for our application that will form the starting point of the application build.

      Let’s use the node:10-alpine image, since at the time of writing this is the recommended LTS version of Node.js. The alpine image is derived from the Alpine Linux project, and will help us keep our image size down. For more information about whether or not the alpine image is the right choice for your project, please review the full discussion under the Image Variants section of the Docker Hub Node image page.

      Add the following FROM instruction to set the application’s base image:

      ~/node_project/Dockerfile

      FROM node:10-alpine
      

      This image includes Node.js and npm. Each Dockerfile must begin with a FROM instruction.

      By default, the Docker Node image includes a non-root node user that you can use to avoid running your application container as root. It is a recommended security practice to avoid running containers as root and to restrict capabilities within the container to only those required to run its processes. We will therefore use the node user’s home directory as the working directory for our application and set them as our user inside the container. For more information about best practices when working with the Docker Node image, check out this best practices guide.

      To fine-tune the permissions on our application code in the container, let’s create the node_modules subdirectory in /home/node along with the app directory. Creating these directories will ensure that they have the permissions we want, which will be important when we create local node modules in the container with npm install. In addition to creating these directories, we will set ownership on them to our node user:

      ~/node_project/Dockerfile

      ...
      RUN mkdir -p /home/node/app/node_modules && chown -R node:node /home/node/app
      

      For more information on the utility of consolidating RUN instructions, read through this discussion of how to manage container layers.

      Next, set the working directory of the application to /home/node/app:

      ~/node_project/Dockerfile

      ...
      WORKDIR /home/node/app
      

      If a WORKDIR isn’t set, Docker will create one by default, so it’s a good idea to set it explicitly.

      Next, copy the package.json and package-lock.json (for npm 5+) files:

      ~/node_project/Dockerfile

      ...
      COPY package*.json ./
      

      Adding this COPY instruction before running npm install or copying the application code allows us to take advantage of Docker’s caching mechanism. At each stage in the build, Docker will check whether it has a layer cached for that particular instruction. If we change package.json, this layer will be rebuilt, but if we don’t, this instruction will allow Docker to use the existing image layer and skip reinstalling our node modules.

      To ensure that all of the application files are owned by the non-root node user, including the contents of the node_modules directory, switch the user to node before running npm install:

      ~/node_project/Dockerfile

      ...
      USER node
      

      After copying the project dependencies and switching our user, we can run npm install:

      ~/node_project/Dockerfile

      ...
      RUN npm install
      

      Next, copy your application code with the appropriate permissions to the application directory on the container:

      ~/node_project/Dockerfile

      ...
      COPY --chown=node:node . .
      

      This will ensure that the application files are owned by the non-root node user.

      Finally, expose port 8080 on the container and start the application:

      ~/node_project/Dockerfile

      ...
      EXPOSE 8080
      
      CMD [ "node", "app.js" ]
      

      EXPOSE does not publish the port, but instead functions as a way of documenting which ports on the container will be published at runtime. CMD runs the command to start the application — in this case, node app.js. Note that there should only be one CMD instruction in each Dockerfile. If you include more than one, only the last will take effect.

      There are many things you can do with the Dockerfile. For a complete list of instructions, please refer to Docker’s Dockerfile reference documentation.

      The complete Dockerfile looks like this:

      ~/node_project/Dockerfile

      
      FROM node:10-alpine
      
      RUN mkdir -p /home/node/app/node_modules && chown -R node:node /home/node/app
      
      WORKDIR /home/node/app
      
      COPY package*.json ./
      
      USER node
      
      RUN npm install
      
      COPY --chown=node:node . .
      
      EXPOSE 8080
      
      CMD [ "node", "app.js" ]
      

      Save and close the file when you are finished editing.

      Before building the application image, let’s add a .dockerignore file. Working in a similar way to a .gitignore file, .dockerignore specifies which files and directories in your project directory should not be copied over to your container.

      Open the .dockerignore file:

      Inside the file, add your local node modules, npm logs, Dockerfile, and .dockerignore file:

      ~/node_project/.dockerignore

      node_modules
      npm-debug.log
      Dockerfile
      .dockerignore
      

      If you are working with Git then you will also want to add your .git directory and .gitignore file.

      Save and close the file when you are finished.

      You are now ready to build the application image using the docker build command. Using the -t flag with docker build will allow you to tag the image with a memorable name. Because we are going to push the image to Docker Hub, let’s include our Docker Hub username in the tag. We will tag the image as nodejs-image-demo, but feel free to replace this with a name of your own choosing. Remember to also replace your_dockerhub_username with your own Docker Hub username:

      • sudo docker build -t your_dockerhub_username/nodejs-image-demo .

      The . specifies that the build context is the current directory.

      It will take a minute or two to build the image. Once it is complete, check your images:

      You will receive the following output:

      Output

      REPOSITORY TAG IMAGE ID CREATED SIZE your_dockerhub_username/nodejs-image-demo latest 1c723fb2ef12 8 seconds ago 73MB node 10-alpine f09e7c96b6de 3 weeks ago 70.7MB

      It is now possible to create a container with this image using docker run. We will include three flags with this command:

      • -p: This publishes the port on the container and maps it to a port on our host. We will use port 80 on the host, but you should feel free to modify this as necessary if you have another process running on that port. For more information about how this works, review this discussion in the Docker docs on port binding.
      • -d: This runs the container in the background.
      • --name: This allows us to give the container a memorable name.

      Run the following command to build the container:

      • sudo docker run --name nodejs-image-demo -p 80:8080 -d your_dockerhub_username/nodejs-image-demo

      Once your container is up and running, you can inspect a list of your running containers with docker ps:

      You will receive the following output:

      Output

      CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES e50ad27074a7 your_dockerhub_username/nodejs-image-demo "node app.js" 8 seconds ago Up 7 seconds 0.0.0.0:80->8080/tcp nodejs-image-demo

      With your container running, you can now visit your application by navigating your browser to your server IP without the port:

      http://your_server_ip
      

      Your application landing page will load once again.

      Application Landing Page

      Now that you have created an image for your application, you can push it to Docker Hub for future use.

      Step 4 — Using a Repository to Work with Images

      By pushing your application image to a registry like Docker Hub, you make it available for subsequent use as you build and scale your containers. We will demonstrate how this works by pushing the application image to a repository and then using the image to recreate our container.

      The first step to pushing the image is to log in to the Docker Hub account you created in the prerequisites:

      • sudo docker login -u your_dockerhub_username

      When prompted, enter your Docker Hub account password. Logging in this way will create a ~/.docker/config.json file in your user’s home directory with your Docker Hub credentials.

      You can now push the application image to Docker Hub using the tag you created earlier, your_dockerhub_username/nodejs-image-demo:

      • sudo docker push your_dockerhub_username/nodejs-image-demo

      Let’s test the utility of the image registry by destroying our current application container and image and rebuilding them with the image in our repository.

      First, list your running containers:

      You will get the following output:

      Output

      CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES e50ad27074a7 your_dockerhub_username/nodejs-image-demo "node app.js" 3 minutes ago Up 3 minutes 0.0.0.0:80->8080/tcp nodejs-image-demo

      Using the CONTAINER ID listed in your output, stop the running application container. Be sure to replace the highlighted ID below with your own CONTAINER ID:

      • sudo docker stop e50ad27074a7

      List your all of your images with the -a flag:

      You will receive the following output with the name of your image, your_dockerhub_username/nodejs-image-demo, along with the node image and the other images from your build:

      Output

      REPOSITORY TAG IMAGE ID CREATED SIZE your_dockerhub_username/nodejs-image-demo latest 1c723fb2ef12 7 minutes ago 73MB <none> <none> 2e3267d9ac02 4 minutes ago 72.9MB <none> <none> 8352b41730b9 4 minutes ago 73MB <none> <none> 5d58b92823cb 4 minutes ago 73MB <none> <none> 3f1e35d7062a 4 minutes ago 73MB <none> <none> 02176311e4d0 4 minutes ago 73MB <none> <none> 8e84b33edcda 4 minutes ago 70.7MB <none> <none> 6a5ed70f86f2 4 minutes ago 70.7MB <none> <none> 776b2637d3c1 4 minutes ago 70.7MB node 10-alpine f09e7c96b6de 3 weeks ago 70.7MB

      Remove the stopped container and all of the images, including unused or dangling images, with the following command:

      Type y when prompted in the output to confirm that you would like to remove the stopped container and images. Be advised that this will also remove your build cache.

      You have now removed both the container running your application image and the image itself. For more information on removing Docker containers, images, and volumes, please review How To Remove Docker Images, Containers, and Volumes.

      With all of your images and containers deleted, you can now pull the application image from Docker Hub:

      • docker pull your_dockerhub_username/nodejs-image-demo

      List your images once again:

      Your output will have your application image:

      Output

      REPOSITORY TAG IMAGE ID CREATED SIZE your_dockerhub_username/nodejs-image-demo latest 1c723fb2ef12 11 minutes ago 73MB

      You can now rebuild your container using the command from Step 3:

      • docker run --name nodejs-image-demo -p 80:8080 -d your_dockerhub_username/nodejs-image-demo

      List your running containers:

      Output

      CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES f6bc2f50dff6 your_dockerhub_username/nodejs-image-demo "node app.js" 4 seconds ago Up 3 seconds 0.0.0.0:80->8080/tcp nodejs-image-demo

      Visit http://your_server_ip once again to view your running application.

      Conclusion

      In this tutorial you created a static web application with Express and Bootstrap, as well as a Docker image for this application. You used this image to create a container and pushed the image to Docker Hub. From there, you were able to destroy your image and container and recreate them using your Docker Hub repository.

      If you are interested in learning more about how to work with tools like Docker Compose and Docker Machine to create multi-container setups, you can look at the following guides:

      For general tips on working with container data, check out:

      If you are interested in other Docker-related topics, please find our complete library of Docker tutorials.



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      How To Deploy a Resilient Node.js Application on Kubernetes from Scratch


      Description

      You may have heard the buzz around Kubernetes and noticed that many companies have been rapidly adopting it. Due to its many components and vast ecosystem it can be quite confusing to find where the path starts to learn it.

      In this session, you will learn the basics of containers and Kubernetes. Step by step, we will go through the entire process of packaging a Node.js application into a Docker container image and then deploying it on Kubernetes. We will demonstrate scaling to multiple replicas for better performance. The end result will be a resilient and scalable Node.js deployment.

      You will leave this session with sufficient knowledge of containerization, Kubernetes basics, and the ability to deploy highly available, performant, and scalable Node.js applications on Kubernetes.

      💰 Use this free $100 credit to try out Kubernetes on DigitalOcean for free!

      About the Presenter

      Kamal Nasser is a Developer Advocate at DigitalOcean. If not automating and playing with modern software and technologies, you’ll likely find him penning early 17th century calligraphy. You can find Kamal on Twitter at @kamaln7 or on GitHub at @kamaln7.

      Resources

      View the slides for this talk, or watch the recording on YouTube (coming soon).

      Transcript of The Commands and Manifests Used

      Be sure to follow along with the recording for an explanation and replace kamaln7 with your own DockerHub username.

      Node App

      1. Create an empty node package: npm init -y
      2. Install express as a dependency: npm install express
      3. index.js

        const express = require('express')
        const os = require('os')
        
        const app = express()
        app.get('/', (req, res) => {
                res.send(`Hi from ${os.hostname()}!`)
        })
        
        const port = 3000
        app.listen(port, () => console.log(`listening on port ${port}`))
        

      Docker

      1. Dockerfile

        FROM node:13-alpine
        
        WORKDIR /app
        
        COPY package.json package-lock.json ./
        
        RUN npm install --production
        
        COPY . .
        
        EXPOSE 3000
        
        CMD node index.js
        
      2. Build the image: docker build -t kamaln7/node-hello-app .

      3. Edit index.js and replace the word Hi with Hello.

      4. Re-build the image and notice Docker re-using previous layers: docker build -t kamaln7/node-hello-app .

      5. Run a container to test it: docker run --rm -d -p 3000:3000 kamaln7/node-hello-app

      6. Look at the running containers: docker ps

      7. Stop the container: docker stop CONTAINER_ID

      8. Push the image to DockerHub: docker push kamaln7/node-hello-app

      Kubernetes

      1. Get worker nodes: kubectl get nodes
      2. Create a deployment: kubectl create deployment --image kamaln7/node-hello-app node-app
      3. Scale up to 3 replicas: kubectl scale deployment node-app --replicas 3
      4. Expose the deployment as a NodePort replica: kubectl expose deployment node-app --port 3000
      5. Look at the newly created service (and the assigned port): kubectl get services
      6. Grab the public IP of one of the worker nodes: kubectl get nodes -o wide
      7. Browse to IP:port to test the service
      8. Edit the service: kubectl edit service node-app
        1. Replace port: 3000 with port: 80
        2. Replace type: NodePort with type: LoadBalancer
      9. Verify that the service was updated: kubectl get service
      10. Run the above command every few seconds until you get the external IP address of the Load Balancer
      11. Browse to the IP of the Load Balancer





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