Use case: this is for people who use a somewhat custom Debian HVM EC2 instance that does not warrant tight configuration management such as provided by e.g. Saltstack. So the natural path for upgrading to Jessie is to… just upgrade the instance to Jessie.
This is, as opposed to creating a new instance based on the latest Debian AMI and moving the various files over. Even if most of the “custom” stuff is cordoned off in a separate volume, there are still all these pesky /etc files to move around. As well as all those files that we always forget about.
Anyway, if a reader has a smoother process, I am interested to hear about it.
Symptom: after the otherwise pleasant and uneventful upgrade to Jessie, systemd complains with
Failed to make us a subreaper: Invalid argument Perhaps the kernel version is too old (< 3.4?)
A quick uname -a later: indeed, the kernel got stuck to 3.2.0 from Wheezie.
The old extlinux package used for those AMI got retired, and with it the extlinux-update command. Time to move to Grub, it would seem.
apt-get install grub2-common grub-common grub-pc grub-pc-bin
When asked, specify both /dev/xvda as locations to install the boot loader. I first tried to specify only the first one, the instance would not boot.
A bit of clean-up as well:
apt-get --purge remove extlinux
Reboot, the instance should come back up.
Traditional word of caution: your mileage may vary, snapshots are your best friends.