Hello folks, If I understood correctly, SCL (Software Collection) is the main Red Hat supported solution to have py3 on el7 and el8, so I gave the rh-python35 collection a try to package the zuulv3 services. Here is how it went: First I added scl-utils-build, rh-python35-build and rh-python35-runtime to the koji target build groups so that a single buildroot could be used for scl and non scl packages. Then I wrote a pip2spec[0] script to render spec file for the 52 missing dependencies[1]. It collects the sdist url, licence and the last version of the pip requirements.txt, to render a valid scl spec file. I couldn't use fedora specs or openstack renderspec because scl is quite intrusive: * The spec defines only one package, regardless of the python runtime * The %build, %install and %check section needs to be wrapped using %{?scl:scl enable %{scl} - << \EOF} ... %{?scl:EOF} Lastly for the zuul package[2], this got a bit more tricky: * The buildroot path are all offsetted with the scl prefix, the confmgmt needed to be adapted to use the new paths: /etc/opt/rh/rh-python35/zuul /etc/opt/rh/rh-python35/sysconfig/zuul /var/opt/rh/rh-python35/lib/zuul /var/opt/rh/rh-python35/log/zuul * The systemd service files also needed to be modified. I first tried to use the scl command wrapper as documented in the guide, but this spawn the service in a subprocess which breaks service reload (the SIGHUP is not sent to the right process). Though a new sysconfig EnvironmentFile is actually easier to activate the scl: PATH=/opt/rh/rh-python35/root/usr/bin:/bin LD_LIBRARY_PATH=/opt/rh/rh-python35/root/usr/lib64 * Finaly, the custom LD_LIBRARY_PATH is a blocker when the service calls a setuid program. The zuul executor uses bubblewrap to contain Ansible execution, and this failed with: error while loading shared libraries: libpython3.5m.so.rh-python35-1.0 cannot open shared object file: No such file or directory To fix that, I had to create symlink for the libpython3.5m.so* and the python3.5 directory to /lib64/, which is not ideal because the scl now affects system wide packages. TL,DR: Using SCL is quite an intrusive change, and unless we somehow remove the scl path prefix, confmgmt needs to be modified to properly configure the services. Moreover, the rh-python35 comes with a limited set of packages and many dependencies will need to be packaged too. Another alternative would be to package a system wide python3 runtime so that we could keep the fedora spec compatibility, but that sounds like a difficult path too. Either way, we will likely lose all the packages that come for free with the default centos python runtime. Though it may be possible to automate most of the work to keep them in sync with the upper-constraints... Best regards, -Tristan [0]: https://softwarefactory-project.io/paste/show/822/ [1]: https://softwarefactory-project.io/r/gitweb?p=config.git;a=blob_plain;f=r... [2]: https://softwarefactory-project.io/r/gitweb?p=scl/zuul-distgit.git;a=tree