Do not upgrade the kernel while provisioning the Vagrant builder VM
Originally created by @anonym on #12532 (Redmine)
The Vagrant builder VMs will never reboot, so upgrading the kernel while
provisioning (which can happend due to the apt-get dist-upgrade
) would
just slow down each build.
All APT repos are frozen (via time-based snapshots) for any given base box, except debian-security, so the only way a kernel update could happen is if it’s in debian-security. But we currently install the kernel from Debian backports, which has a higher version than the one in stable/debian-security, so it’s highly unlikely that an upgrade will be pulled, so caring about this might seem unnecessary.
However, I expect that once we upgrade the builder VM to Debian Stretch, we will not install any backported kernel for a while (there probably won’t be one) and during this window we will be affected by this. We’ll probably have such a window each time we upgrade to a new Debian release. Hence we should, when generating the base box, pin the kernel that we end up with so that it is never upgraded.