This is mostly aimed at Debian/Ubuntu, but I feel savvy enough on a variety of distros to be able to adapt the solution for one distro to another.
Here's my scenario. There are a few situations when the boot process will drop you to the shell (usually busybox) of the initrd. Most notably whenever you run a hardware RAID for which drivers have to be rebuilt for each and every new kernel revision. I'd like to be able to access the rescue system the same way as I would access the fully booted system.
I reckon it'd be possible to put static builds of the shell(s) and
sshd (OpenSSH or dropbear) into the initrd and have been looking for an existing solution that I can adjust to my needs.
Assuming there is no existing solution (since I have searched for quite a while) what do I need to consider aside from using static builds where possible (or supply the libs)? Is it reasonable to simply cache a static build of dropbear and use
/etc/initramfs-tools/hooks to embed that along with a "converted" OpenSSH
sshd_config and the original host keys?