Migrating Nginx to Docker

There are many ways to install a Nginx web server on Linux. It can be installed using OS’s packager manager, either from distro’s repositories on from Nginx’s official repos. It can be compiled from source. But my favorite way is definitely in a Docker container.

Main benefits are:

• Nothing is installed on the system
• Many different versions are available (without adding external repositories)
• It’s easy to transition from a normal install to Docker

Step 1: Preparing Nginx configuration file

I already wrote about creating a basic Nginx configuration file here, so I will just briefly point out what was changed to be used in Docker.

...

    ssl_certificate        /etc/ssl/<domain_name>_cert.pem;
    ssl_certificate_key    /etc/ssl/<domain_name>_key.pem;
    ssl_client_certificate /etc/ssl/<domain_name>.pem;
    ssl_verify_client on;

    server_name <domain_name> www.<domain_name>;

    root /<domain_name>;  <----- read files from root directory
    index index.html;
    location / {
        try_files $uri $uri/ =404;
    }
...

Note <domain_name> is a valid domain name, and <— points to changed part

The only thing really changed in the path to website contents. It had to change because nginx Docker image doesn’t have /var/www path.

Step 2: Preparing Docker Compose file

To keep everything organized, let’s create a directory to store docker and Nginx configuration files.

mkdir /opt/compose
touch <domain_name>.conf  # add Nginx config here
touch docker-compose.yaml

Open docker-compose.yaml with a text editor and add following content:

version: '3.9'
services:
  nginx:
    image: nginx
    container_name: nginx
    volumes:
      - ./<domain_name>.conf:/etc/nginx/conf.d/<domain_name>.conf
      - /etc/ssl/:/etc/ssl/
      - /opt/website/public/:/<domain_name>
    ports:
      - "80:80"
      - "443:443"

The most import part is volumes, here we are:

• Mounting Nginx configuration files to Nginx folder in the container
• Mounting directory with TLS certification to the container
• And mounting website files to container’s root directory

Step 3: Launching Docker Compose

Make sure that Nginx config and compose file are in the same directory, and then launch Compose:

docker compose up -d nginx

In case of an error, check logs:

docker logs nginx

If the configuration files will change, and it’s essential to keep the web server without interruptions, it can be safely reloaded with:

docker exec -it nginx nginx -s reload

where nginx -s reload is the command that will executed in the container.