Making a local Ubuntu/Debian repository mirror

Using debmirror the entire contents of the official package repositories can be copied locally.

• Installing the prerequisites:

sudo apt-get install debmirror

• Making a new folder for the mirror and installing the ubuntu cryptographic key:

mkdir /var/ubuntu-mirror
gpg --keyring /usr/share/keyrings/ubuntu-archive-keyring.gpg --export | gpg --no-default-keyring --keyring /var/ubuntu-mirror/trustedkeys.gpg --import

• Starting the sync process (downloading the AMD64 packages for bionic and focal releases of Ubuntu, using the Romanian mirror). It will download about 330GB of data the first time. You can run periodically this command, to pull the latest versions of the packages.

GNUPGHOME=/var/ubuntu-mirror debmirror \                                                       
        -a amd64 \
        --no-source \
        -s main,restricted,universe,multiverse \
        -h ro.archive.ubuntu.com \
        -d bionic,bionic-security,bionic-updates,bionic-backports,focal,focal-security,focal-updates,focal-backports \
        -r /ubuntu \
        --progress \
        --method=http \
        /var/ubuntu-mirror/

• To make the data available over the local network I’m using nginx:

sudo apt-get install nginx

• Edit the nginx configuration: you need to map the http://<local_ip>/mirror path of the server to the /var/ubuntu-mirror/ path in the filesystem. To do this you must edit the /etc/nginx/sites-available/default file to add the mirror location, inside the server section.

Add the lines marked with + (without adding the + sign at the start of each line).

 server {
 	listen 80 default_server;
 	listen [::]:80 default_server;
 
 # ...
 # ... 
+	location ^~ /mirror {
+		alias /var/ubuntu-mirror;
+		autoindex on;
+		try_files $uri $uri/ =404;
+	}
 # ...
 # ...
 
 }

• Restart nginx to pick up the new configuration:

sudo systemctl restart nginx

• Making computers use the local mirror: edit manually the /etc/apt/sources.list. See the snippet below (assuming the IP of the mirror is 192.168.111.118).

deb http://192.168.111.118/mirror focal main restricted universe multiverse
deb http://192.168.111.118/mirror focal-updates main restricted universe multiverse
deb http://192.168.111.118/mirror focal-backports main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu focal-security main restricted universe multiverse

Additionally, you can use an ansible script to switch to the mirror:

  - name: remove support for i386
    become: true
    shell: dpkg --remove-architecture i386

  - name: replace apt mirror on ubuntu
    become: true
    copy:
      dest: /etc/apt/sources.list
      content: |
               deb http://192.168.111.118/mirror focal main restricted universe multiverse
               deb http://192.168.111.118/mirror focal-updates main restricted universe multiverse
               deb http://192.168.111.118/mirror focal-backports main restricted universe multiverse
               deb http://security.ubuntu.com/ubuntu focal-security main restricted universe multiverse

  - name: update apt cache on ubuntu
    become: true
    apt:
      update_cache: yes