Steps don't work anymore.

[maka-io]

Trying to install vts-backend results in the following apt error:

sudo apt install vts-backend
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 vts-backend : Depends: vts-mapproxy (>= 1.39) but it is not going to be installed
               Depends: vts-mapproxy-tools but it is not going to be installed
               Depends: vts-tools (>= 1.71) but it is not going to be installed
               Depends: vts-vtsd (>= 1.20) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

[vaclavblazek]

You need to add universe repository to you /etc/apt/sources.list after main repository. Bare functioning Ubuntu configuration looks like this:

deb http://archive.ubuntu.com/ubuntu bionic main universe

After updating this file, do not forget to run apt update.

Please, install nginx first, there is a vexing symlink problem in vts-backend package that has not been fixed yet:

apt install nginx

Once nginx is installed vts-backend should install and run like a charm.