Comment 1 for bug 1441117

I had a quick browse through this bug, and I came up with this as a solution for including both prepending and appending hooks:

In the config you'd have two config options:

    default_processing_hooks = ramdisk_error,scheduler,validate_interfaces

    processing_hooks = $defaults

In the code '$defaults' would get resolved to the values stored in default_processing_hooks. If a operator wanted to add their own hooks before or after the defaults they could like:

   processing_hooks = prehook,$defaults,posthook,secondposthook

What do you think? This was just my initial thoughts after reading the bug report and the comments on the linked patch.