How did I fix «Something wicked happened resolving 'apt.dockerproject.org:https' (-5 - No address associated with hostname)»?
The error occured because I had the
deb https://apt.dockerproject.org/repo debian-jessie main declaration in the
dockerproject.org repository has been shut down since 2020-03-31:
So I deleted the
/etc/apt/sources.list.d/docker.listfile and added the right repository:
add-apt-repository \ "deb [arch=amd64] https://download.docker.com/linux/debian \ $(lsb_release -cs) \ stable"