Re: ldap and reloading

[Ian Kent <raven@themaw.net>]

Stef Bon wrote:
> Hello,
> 
> when using static file maps, or even executable maps, when the map 
> changes, you'll have to reload the daemon to make these changes effective.
> 
> How does this work when all the data is in ldap? Does the automounter 
> still creates a sort of snapshot of the map in memory, and to reread the 
> data provided by ldap, a reload is neccesary? ldap is well know for that 
> this is not needed. For example with postfix, it can use static maps, 
> and when something changes, it has te be restarted. But when the lookup 
> data (for local users for example) is in ldap, this is not neccesary.

That's not quite right.

If you use the "browse" option then the entire map must be read in at
start. If not then autofs remembers entries that it has seen and
attempts to check their currency at lookup.

Each lookup should check if the entry is still up to date and attempts
to work out if the map has changed (although it's not quite as simple as
that). If we think the map has changed a re-load should be triggered
internally. Following the (or any) re-load there is a cleanup which is
probably why it looks like map changes aren't seen. Any changes in
multi-mount entries cannot be seen until after they have expired away,
because of the need to maintain the context of the entry over the
duration of the mount.

Direct maps don't quite do this properly, partly because of the way they
work and partly because of an issue I haven't addressed yet.

Clearly, with program maps, we need to rely on the re-load to a large
extent but a best effort is made to work out if the entry is stale,
however, we just don't have anything really to use to establish this, so
 a re-load is needed to clean them up.

Ian