[kea-dev] Suggestion for new hooks: server startup, shutdown, reload
tomasz at isc.org
Mon Dec 1 15:57:11 UTC 2014
On 19.11.2014 17:04, Chaigneau, Nicolas wrote:
> I think it could be extended with new hook points. What do you think of the following proposal ?
> - "server startup" hook:
> Triggered after server has been started, configuration read, subnets initialized, leases loaded from backend; and just before the server actually starts processing DHCP packets.
> This would allow a hook library to:
> - Read its configuration (if it has one)
> - Perform the initialization steps it requires
> - If something wrong happens it could report through an output error code, which would cause the server to stop (as when the main configuration is incorrect, for instance).
> The hook should provide access to anything the hook library needs.
> For my needs, I can think of the subnets collection and the leases collection. The list is open though.
> - "server shutdown" hook:
> Triggered just before the server is about to be shut down.
> This would give a hook library a chance to perform some termination steps, if need be. Close handles, etc.
> (although on Linux it's not strictly needed, it's still cleaner to do so).
Both are useful, if you haven't done so, please submit a ticket and
describe your proposal. (Apologies if you already did that. I just
returned from 2 weeks vacation and I'm not entirely up to speed). We'll
process it the usual way - review on a team call on Wednesday and assign
it to a milestone.
> - "library reload" hook:
> Triggered after the hook library is reloaded (after the server has processed the "libreload" command)
> I think the same possibilities as in "server startup" should be provided.
Does it make sense? For a library, the libreload should be
indistinguishable from server shutdown and startup events, i.e. a
library is unloaded and later loaded again. So I don't see any useful
way to trigger such hook. If you need to know whether the library is
loaded upon startup or as a result of libreload, we could possibly add
an argument to load() that would signal that.
So, do you really need this? If yes, would an argument passed to load do
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