- we cannot install packages, which are not authenticated:

INFO: voicerepublic-staging.sky.ungleich.ch: Executing code for __package_apt/deb-multimedia-keyring
Reading package lists...
Building dependency tree...
Reading state information...
The following NEW packages will be installed:
  deb-multimedia-keyring
  0 upgraded, 1 newly installed, 0 to remove and 13 not upgraded.
  Need to get 14.4 kB of archives.
  After this operation, 46.1 kB of additional disk space will be used.
  WARNING: The following packages cannot be authenticated!
    deb-multimedia-keyring
    E: There are problems and -y was used without --force-yes
    ERROR: voicerepublic-staging.sky.ungleich.ch: Command failed: ssh -o User=root -q voicerepublic-staging.sky.ungleich.ch /bin/sh -e /var/lib/cdist/object/__package_apt/deb-multimedia-keyring/.cdist/code-remote
    INFO: cdist: Total processing time for 1 host(s): 72.07943892478943
    ERROR: cdist: Failed to configure the following hosts: voicerepublic-staging.sky.ungleich.ch