Synchronisation of Ubuntu repositories failing on a Centos 7 host

How to create the /pulp_deb_signing.key ?

I followed the procedure you pointed to me

https://docs.orcharhino.com/or/docs/sources/usage_guides/attach_existing_hosts_guide.html

Down in the section Attaching Hosts Manually, then >> Debian/Ubuntu Hosts

The instruction said to add the key as below

wget “https://orcharhino.example.com/pub/pulp_deb_signing.key” -O - | apt-key add -

I am wondering how to create the pulp_deb_signing.key for Debian / Ubuntu

Then seached and tried making a key in following the procedure in the lin below, but at the end it did not work as the server is taking this certificate as self signed certificate

The in following the procedure on the first link and after creating the local repository in /etc/apt/sources.list.d

apt-get update && apt-get -y install apt-transport-katello katello-upload-profile

The error message below:

"Reading package lists… Done

E: The repository ‘http://foreman1.intra.avancie.com/pulp/deb/Default_Organization/Library/custom/Ubuntu_18_04_Bionic/Ubuntu_18_04_Repo-bionic-updates default Release’ is not signed.

N: Updating from such a repository can’t be done securely, and is therefore disabled by default.

N: See apt-secure(8) manpage for repository creation and user configuration details.

root@ubuntuclitest:/etc/apt/sources.list.d"

Please help.