I'm using your image to build RPM packages on Gitlab with CI/CD pipelines. I need to modify the /home/rpmbuilder/.rpmmacros file so that the Gitlab pipeline can find the resulting SRPM and RPM files but since the file/directory are owned by root, I have to "sudo echo My_Great_Macro 1 >> ~/.rpmmacros".
This is a bit jankey and I recommend ensuring the .rpmmacros and rpmbuild file/directory are owned by the rpmbuilder user.