To install Ansible on Debian (10).

Open a shell, and as root user run:

apt-get update 
apt-get install -y gnupg2 
sh -c 'echo "deb http://ppa.launchpad.net/ansible/ansible/ubuntu trusty main" >> /etc/apt/sources.list' 
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 93C4A3FD7BB9C367 
apt update 
apt install ansible -y