On Tue, Aug 27, 2013 at 12:34:27PM +0200, Sumit Bose wrote:
On Mon, Aug 26, 2013 at 10:16:34PM +0200, Jakub Hrozek wrote:
> On Mon, Aug 26, 2013 at 04:02:59PM -0400, Simo Sorce wrote:
> > On Mon, 2013-08-26 at 21:41 +0200, Jakub Hrozek wrote:
> > > On Mon, Aug 26, 2013 at 03:35:09PM -0400, Simo Sorce wrote:
> > > > On Mon, 2013-08-26 at 21:17 +0200, Jakub Hrozek wrote:
> > > > > On Mon, Aug 26, 2013 at 06:18:05PM +0200, Sumit Bose wrote:
> > > > > > On Mon, Aug 26, 2013 at 05:20:21PM +0200, Jakub Hrozek
wrote:
> > > > > > > On Fri, Aug 23, 2013 at 03:44:09PM +0200, Sumit Bose
wrote:
> > > > > > > > Hi,
> > > > > > > >
> > > > > > > > currently in ipa-server-mode only the AD groups
memberships are
> > > > > > > > available. This patch adds the IPA group
memberships to trusted AD
> > > > > > > > users.
> > > > > > > >
> > > > > > > > This patch is missing some unit tests for some of
the helper functions.
> > > > > > > > I will send them later, but I didn't want to
delay the next release.
> > > > > > > >
> > > > > > > > bye,
> > > > > > > > Sumit
> > > > > > >
> > > > > > > I haven't done any testing yet but do we need the
timeout? Since the
> > > > > > > initgroups is a rare operation and on logins we
generally want to have
> > > > > > > the correct memberships, can we just rely on responder
caching?
> > > > > >
> > > > > > I was thinking of situations where multiple logins happen
in a short
> > > > > > time. Additionally I think even if group memberships of a
user might
> > > > > > change often the mapping of AD to IPA group memberships via
the external
> > > > > > groups will only change rarely.
> > > > > >
> > > > > > Maybe we can a cache time option to make it more flexible?
> > > > > >
> > > > > > bye,
> > > > > > Sumit
> > > > >
> > > > > I was thinking about this more on my way home and I think
you're
> > > > > right we need to optimize the ipa_server_mode. This could cause
the "8AM
> > > > > login rush" to be a real bottleneck.
> > > > >
> > > > > But I think we can exploit the fact that we know the server well
during
> > > > > the ipa_server_mode. What about this approach?
> > > > > 1. on startup we download all external groups
> > > >
> > > > it could be a huge set, and would cause a huge load if someone runs
a
> > > > puppet script to reconfigure and restart a few 1000 machines with
sssd.
> > > >
> > >
> > > A huge set of external groups?
> >
> > Why not ?
>
> No technical reason. I just don't see that as a common use-case that's
> all.
>
> >
> > > > > 2. store the largest lastUSN to the server mode context
> > > >
> > > > we already have this afaik
> > >
> > > No we don't. This is new code just for the server mode.
> >
> > Ahh, that explains some things, sorry.
>
> No problem, lot of patches are flailing around, I know.
>
> >
> > > >
> > > > > 3. on subsequent lookups, only download and store groups
with higher
> > > > > lastUSN
> > > >
> > > > if you change server you are back to square zero though
> > > >
> > >
> > > Which is never during in the server mode. (except for slapd outages etc)
> > >
> > > > > 4. perform the lookup always. It's on the server after
all so
> > > > > network LDAP search is quite cheap.
> > > >
> > > > not sure I understand what this means ?
> > >
> > > The current patch re-downloads external groups every 600 seconds and if
> > > 600 seconds hasn't passed, uses cache. I'm proposing we download
> > > (&(objectClass=externalGroup)(lastUSN>=stored_last_usn)) on every
> > > request because in the server mode the latency is not an issue.
> >
> > 600 is a lot :(
>
> yes, that's why I was trying to come up with something more optimized..
>
> >
> > > >
> > > >
> > > > The point of checking initgroups at login is to assure the right
> > > > memberships are in place, both for security reasons and to allow a
user
> > > > to logoff and login back again and make sure eh gets new group
> > > > memberships if he has been granted any new ones.
> > > >
> > > > Loggin off then back on is the only way to gain system-wide the new
> > > > memberships so that's what an administrator will tell a user to
do if
> > > > the user complains he can't access something.
> > > >
> > > > This means that caching can't last long as the side effects are
severe.
> > > > So anything more than a few seconds would probably be bad. A few
seconds
> > > > make total sense for load issues when someone is abusing pam atuh
(for
> > > > example someon eusing basic auth wired to pam auth for a a web
server
> > > > that will receive potentially many tens of authentications for the
same
> > > > user within a fraction of a second as each image and file is loaded
in a
> > > > new connection).
> > > >
> > > > In this case you really want to completely cache the whole operation
and
> > > > not touch the network for any reason, otherwise latency will make
things
> > > > unbearable. But that's the extent to which you want to go, a few
seconds
> > > > for auth bursts, nothing more.
> > > >
> > > > Simo.
> > >
> > > The latency in the server mode is really small, we should always be
> > > talking to the local server.
> >
> > I think we shouold defer this until the synrepl control is available in
> > 389ds, then we can simply have a persistent search open using syncrepl
> > and we'll get changes as needed and no more that that (including
> > deletions).
> >
> > Simo.
>
> Yes, that sounds like a very good solution, I just think we also need to
> have a way to handle the external groups in time for 1.11/3.3. If we can
> leverage a 389DS control later, even better.
What about using a shorter timeout, e.g. 10s, for 1.11.0 and
optimizations in 1.11.x?
bye,
Sumit
That sounds good to me.