I've assumed you have created a DNS A record for trilium.yourdomain.com that you want to use for your Trilium server.

1. Download docker image and create container

    docker pull zadam/trilium:[VERSION]
    
    docker create --name trilium -t -p 127.0.0.1:8080:8080 -v ~/trilium-data:/home/node/trilium-data zadam/trilium:[VERSION]
   

2. Configure Apache proxy and websocket proxy

   1. Enable apache proxy modules

       a2enmod ssl
       a2enmod proxy
       a2enmod proxy_http
       a2enmod proxy_wstunnel
      

   2. Create a new let's encrypt certificate

       sudo certbot certonly -d trilium.mydomain.com
      

      Choose standalone (2) and note the location of the created certificates (typically /etc/letsencrypt/live/...)

   3. Create a new virtual host file for apache (you may want to use apachectl -S to determine the server root location, mine is /etc/apache2)

       sudo nano /etc/apache2/sites-available/trilium.yourdomain.com.conf
      

      Paste (and customize) the following text into the configuration file

       <VirtualHost *:80>
           ServerName http://trilium.yourdomain.com
       	RewriteEngine on
               RewriteRule ^ https://%{SERVER_NAME}%{REQUEST_URI} [END,QSA,R=permanent]
       </VirtualHost>
       <VirtualHost *:443>
           ServerName https://trilium.yourdomain.com
           RewriteEngine On
       	RewriteCond %{HTTP:Connection} Upgrade [NC]
       	RewriteCond %{HTTP:Upgrade} websocket [NC]
       	RewriteRule /(.*) ws://localhost:8080/$1 [P,L]
           AllowEncodedSlashes NoDecode
           ProxyPass / http://localhost:8080/ nocanon
           ProxyPassReverse / http://localhost:8080/
           SSLCertificateFile /etc/letsencrypt/live/trilium.yourdomain.com/fullchain.pem
           SSLCertificateKeyFile /etc/letsencrypt/live/trilium.yourdomain.com/privkey.pem
           Include /etc/letsencrypt/options-ssl-apache.conf
       </VirtualHost>
      

   4. Enable the virtual host with sudo a2ensite trilium.yourdomain.com.conf

   5. Reload apache2 with sudo systemctl reload apache2

3. Create and enable a systemd service to start the docker container on boot

   1. Create a new empty file called /lib/systemd/system/trilium.service with the contents

       [Unit]
       Description=Trilium Server
       Requires=docker.service
       After=docker.service
       	
       [Service]
       Restart=always
       ExecStart=/usr/bin/docker start -a trilium
       ExecStop=/usr/bin/docker stop -t 2 trilium
       	
       [Install]
       WantedBy=local.target
      

   2. Install, enable and start service

       sudo systemctl daemon-reload
       sudo systemctl enable trilium.service
       sudo systemctl start trilium.service