Packaging Tutorial Web UI

Setup for static output

By default, the Next.js framework creates a server-side rendered application. For the Tutorial Web UI we want the output to be static files that can be served by a web server. We will use NGINX* web server for this.

To do this we need to set the output option in the next.config.ts file to export.

const nextConfig = {
    output: 'export',
}

This will allow us to use the npx next build command to create the production ready static files in the Dockerfile.

Creating a Dockerfile

Similar to the Tutorial Server, the Tutorial Web UI application needs to be packaged in a Container image.

We want it to serve the static files from the Next.js application, but we want the Node.js* server available to minify these files in the first place. We don’t need to have the Node.js server running in the final image, so we will use a multi-stage build to create the final image.

The first stage will build the application and the second stage will copy the results in to a minimal NGINX image.

Note

The NGINX image is much smaller than the Node.js image, and so the final image will be smaller. Again we only take base images from reputable sources.

Add the following to a file Dockerfile in the tutorial-web-ui directory.

# Stage 1: Build the application
FROM node:22 AS build

WORKDIR /app

COPY package.json package-lock.json next-env.d.ts postcss.config.mjs tsconfig.json next.config.ts ./

RUN npm install

COPY app app
COPY public public

RUN npx next build

# Stage 2: Serve the application
FROM nginxinc/nginx-unprivileged:alpine-perl

EXPOSE 8080

USER nginx

COPY --from=build /app/out /usr/share/nginx/html

Build the Container image

Build the Container image using the Dockerfile.

docker build --platform=linux/amd64 -t tutorial-web-ui-image .

Examining the Container image shows is 1/10th the size of the Tutorial Server image because we were able to use a multi-stage build.

~ $ docker images | grep "tutorial.*image"

tutorial-web-ui-image   latest    979019e086eb   47 minutes ago   87.2MB
tutorial-server-image   latest    16bc7692277d   50 minutes ago   563MB

Testing the Container image

docker run -p 8080:8080 tutorial-web-ui-image

Open your web browser to http://localhost:8080 to see the default page.

The Tutorial Web UI application is now running in a Container image but is not yet connected to the Tutorial Server.

In the development stage we had a special mapping that pointed to the API at http://localhost:8000. This is not available in the final image, and now we are in production mode, so it expects to access the API at the same URL from which the HTML, CSS, and JavaScript* files are served.

We will see how to set this up in the next section.

Note

This is a security feature of modern browsers to prevent cross-site scripting.

Understanding the Container image

Similar to the Tutorial Server, we can jump in to this container image to inspect it.

docker run -it --platform=linux/amd64 --entrypoint /bin/sh tutorial-web-ui-image

Running some commands in this shows that the base container is based on the Alpine Linux* distribution.

~ $ cat /etc/issue
Welcome to Alpine Linux 3.21
Kernel \r on an \m (\l)

~ $ uname -a
"Linux 2337e849911f 6.10.14-linuxkit #1 SMP Fri Nov 29 17:22:03 UTC 2024 x86_64 Linux"

~ $ ls /usr/share/nginx/html
404.html     50x.html     _next        favicon.ico  file.svg     globe.svg    index.html   index.txt    next.svg     vercel.svg   window.svg
~ $ ls /etc/nginx/conf.d/default.conf
/etc/nginx/conf.d/default.conf

~ $ nginx -V
nginx version: nginx/1.27.4
built by gcc 14.2.0 (Alpine 14.2.0)
built with OpenSSL 3.3.2 3 Sep 2024 (running with OpenSSL 3.3.3 11 Feb 2025)
TLS SNI support enabled
...

~ $ whoami
nginx
~ $