fix provided in https://github.com/MariaDB/mariadb.org-tools/pull/108
To build >10.7 branch we need libzstd.dev >= 1.1.3 that is unfortunately not available in debian9 (https://packages.debian.org/stretch/libzstd-dev).
The package is available through backports: https://packages.debian.org/stretch-backports/libzstd-dev
Fix: install the bpo version in the docker image.
https://github.com/MariaDB/mariadb.org-tools/pull/108
danblack can I kindly ask you to double check if this seems OK?
I have just found https://github.com/MariaDB/server/commit/8c5e5e1be9353b90f341aad73cb3d2ed7c405a96 and now I am not sure if we should have done that.
Good call on the double check - buildbot.mariadb.org/ci_build_images/debian.Dockerfile adding dependencies will add a runtime dependency (for the rocksdb package) on the backports to the released binaries from them (if we where releasing from them from bb.org).
So yes, revert that part of the commit and keep centos8.
Ok, thanks danblack. But then it still unclear to me how we need to fix this. I will check with vladbogo what we can do about it. And maybe also try to understand how old BB is building 10.7 on debian9.
Revert the addition of libzstd-dev for debian 9.
> Revert the addition of libzstd-dev for debian 9.
Sure, but this is not going to resolve the buildbot building problem 
vladbogo what's your take on that?
Not sure. I guess that the only possible option is to remove the dependency from the server side. Buildbot wise not sure what we can do
Yes, fix the server debian/autobake.sh to do a distro version (not package version see MDBF-347, MDEV-28011) based removal of libzstd-dev
Debian 9 end of life is June 30, 2022. So would it be just put on back burner and consider as done?
Thanks for the review illuusio
There's still more Debian 9 releases. As MDEV-28014 showed we have a fragility problem with the apt-cache.
While Debian 9 is going to be EOL soon, having the framework of tests against absolute distro versions is a good place to start.