Initramfs is used for getting the root filesystem mounted and passing control the real init on the real root fs. Once the kernel boots, it passes control to the init in the initramfs. This init then runs scripts that are responsible for checking if the root device is configured properly and capable of mounting the root fs on it. In parallel, behind the scenes, udev runs and uses the help of blkid to run "admin" scripts like "mdadm", "lvm", "cryptsetup" to configure the root device. This is all event based, i.e the devices are configured as and when they become available. However the exception to this is configuring the LUKS devices, which are configured using cryptsetup. The script that runs cryptsetup, first checks up if the device which is to be configured as an encrypted device, is available. If not then it waits for some time and then it checks again if the device is available or not. If not then it will simply give up and get the user to a busybox prompt. If the device is available, then cryptsetup is called and the device is configured as a LUKS device. Once the device is available a udev event is generated and again, udev runs blkid and calls whatever admin script needs to be called if any other subsystem is stacked on top of this LUKS device. While all this is good, there are two observations to be made here:

a. The invocation of cryptsetup is procedural and not completely event based.

b. There is a repeatition of code for mounting, checking filesystems, crypt devices, LVM devices and so on - one code path is found in upstart jobs and the other in initramfs.

So one idea that lets you remove this duplication and at the same time enables the LUKS devices in an event based fashion, is to make the initramfs event based in the true sense, by bringing in upstart in initramfs. This means that we copy the jobs in /etc/init/ in initramfs and run them at boot time. This brings in the simplicity, elegance and robustness of upstart in initramfs and also gives you more flexibility to handle the events in a way that you want