Tutorial: Dockerize a Node.js Express application

Create an empty project with Node.js

1. Click New Project on the Welcome screen or select File | New | Project from the main menu.

2. In the dialog that opens, select Node.js in the left-hand pane.

3. Specify the location of the application and its name, for example, hello_world_docker.

4. Specify the local Node.js runtime to use. Accept the suggested installation or select another one from the list, or even click Download if you do not have Node.js on your machine yet. Learn more from Create a new Node.js application.

   

5. Click Create.

Populate the application

1. Let us create a separate folder for our application, this will help us later map local folders to folders in the container.

   To do that, open the Project tool window Alt+1, right-click the project folder, select New from the context menu, and then select Directory. In the popup dialog that appears, specify the name of the folder, for example, app.

   

2. Now it is time to create a JavaScript file to place the code of our application in.

   From the context menu of the app folder, select New from the context menu, and then select JavaScript File.

   

   In the popup dialog that appears, specify the name of the file, for example, hello_express.js.

   

3. Open the newly created hello_express.js file in the editor and type the following code:

   const express = require('express'); const app = express(); app.get('/', function(req, res) { res.send('Hello World!') }); app.listen(3000,function() { console.log('Example app listening on port 3000!') });

4. As you might have expected, the express reference is not resolved and highlighted as an error. However, WebStorm suggests a quick-fix as you hover over the reference:

   

   When you click the Install 'express' link, express is added to the package.json file and installed.

   

Run the application locally

Let us run our application locally to make sure it works as expected.

• Open the hello_express.js file, right-click anywhere in the editor tab, and select Run 'hello_express.js' from the context menu.

  

  The Run tool window opens showing Example app listening on port 3000!.

  If you open the browser at http://localhost:3000, you will see that the page shows Hello World!, as expected.

  

Create a Dockerfile

1. From the context menu of the project folder, select New from the context menu, and then select Dockerfile.

   

2. Open the newly created Dockerfile and type the following code:

   FROM node:22-alpine WORKDIR /tmp COPY package*.json . RUN npm ci --omit=dev COPY ./app/ ./app/ CMD ["node","./app/hello_express.js"]

   This Dockerfile contains instructions for building an image based on the node:22 image from Docker Hub.

   When you run a container from this image, Docker sets copies the contents of the /app/ directory to the /tmp/app/ directory in the container (in our case, the /app/ directory contains the hello_express.js file). The package.json file is copied to /tmp/.

   Then Docker sets the current working directory to /tmp and runs node ./app/hello_express.js. As a result, the container log should show Example app listening on port 3000!.

Build and run an image from the Dockerfile

1. Open the Dockerfile in the editor, click gutter icon, select Run, and then select Run on 'Docker'.

   

2. WebStorm creates a Dockerfile run configuration, which builds an image from the Dockerfile and then runs a container based on that image.

   

   To see the whole process, open the Build Log tab in the Services tool window.

   

3. You can share the image with others, for example, to demonstrate exactly how your application is expected to run, without the need to install Node.js (only Docker is required).

Expose the container's port

• Open your Dockerfile and add the following line to it:

  EXPOSE 3000

  Now your Dockerfile will look as follows:

  FROM node:22-alpine WORKDIR /tmp COPY package*.json . RUN npm ci --omit=dev COPY ./app/ ./app/ EXPOSE 3000 CMD ["node","./app/hello_express.js"]

Create a Node.js Express application

1. Click New Project on the Welcome screen or select File | New | Project from the main menu.

2. In the dialog that opens, select Express in the left-hand pane.

3. Specify the location of the application and its name, for example, node_express_docker.

4. Specify the local Node.js runtime to use. Accept the suggested installation or select another one from the list, or even click Download if you do not have Node.js on your machine yet. Learn more from Create a new Node.js application.

   

5. Accept the default settings for the View Engine and the Stylesheet Engine.

6. Click Create.

WebStorm generates a simple Express application and installs the dependencies listed in package.json.

Run an application locally

To make sure our autogenerated application works, let us first run it locally. You may notice that WebStorm has also generated a bin/www run/debug configuration of the type Node.js.

1. Select the bin/www run/debug configuration from the Run widget on the toolbar and click next to it.

   

   The Run tool window opens showing the application output.

   

2. Open the browser at http://localhost:3000. The page shows a welcome message:

   

3. Let's slightly update the code so we don't have to open the browser but can get some response from the application in the console. To do that, open bin/www and add the following line, for example, inside the onListening() function:

   console.log("Hello world");

   If we now rerun the application, the Run tool window looks as follows:

   

Create a Dockerfile

1. In the Project tool window, right-click the project name, point to, New and click File.

2. In the New File dialog, type Dockerfile and press Enter.

3. Paste the following code to the new Dockerfile:

   FROM node:22-alpine WORKDIR /tmp COPY package*.json . RUN npm ci --omit=dev COPY ./bin/ ./bin/ COPY ./public/ ./public/ COPY ./routes/ ./routes/ COPY ./views/ ./views/ COPY ./app.js . CMD ["npm","start"]

   As you can see, here we copy local folders separately step by step.

4. Let us expose the container port by adding EXPOSE 3000 to our Dockerfile:

   FROM node:22-alpine WORKDIR /tmp COPY package*.json . RUN npm ci --omit=dev COPY ./bin/ ./bin/ COPY ./public/ ./public/ COPY ./routes/ ./routes/ COPY ./views/ ./views/ COPY ./app.js . EXPOSE 3000 CMD ["npm","start"]

Deploy and run the application

• To deploy and run the application, click gutter icon, select Run, and then select Run on 'Docker'. The application is now running in a container:

  

Bind ports

To make the application accessible from outside a Docker container, we need to bind the container port, which in our example is 3000, to a port on the host.

You can do that right in a running container or in a Dockerfile run/debug configuration, as described above.

• In the Dashboard tab, click Add in the Ports area and then specify the container port, in our example, it is 3000.

  

  Click Modify options, set a tick next to Host port, and specify the host port in the field that is added. On our example, let it be 3001.