ldap package question

[John Gordon]

I'm using the ldap package to connect to an ldap server and run a query.
Very simple code, along these lines:

con = ldap.initialize(uri)
con.simple_bind_s(user, password)
results = con.search_s(group, ldap.SCOPE_SUBTREE, filter, attrs)
for r in results:
# inspect the results

I'm experiencing some intermittent failures and I think it's because the
URI I'm connecting to is actually an alias (proxy? load-balancer? I'm not
sure of the right word here) for a pool of servers, one of which is flaky.

Is there a way to ask the connection object exactly which server I'm
connected to?

 

[Michael Ströder]

I'm using the ldap package to connect to an ldap server and run a query.
Very simple code, along these lines:

con = ldap.initialize(uri)
con.simple_bind_s(user, password)
results = con.search_s(group, ldap.SCOPE_SUBTREE, filter, attrs)
for r in results:
# inspect the results

I'm experiencing some intermittent failures

What effects do you see? How do you detect a failure?

and I think it's because the
URI I'm connecting to is actually an alias (proxy? load-balancer? I'm not
sure of the right word here) for a pool of servers, one of which is flaky.

There are LDAP proxies with load-balancing and network-level
load-balancers. What is deployed at your site? What are the LDAP server?

Is there a way to ask the connection object exactly which server I'm
connected to?

Since load-balancers typically share a virtual IP you cannot really
determine to which server your client is connected. It's up to this
system's configuration. You could ask some monitoring entry in the LDAP
server itself but this might also be flaky depending how your LDAP
session is dispatched to the LDAP servers. You better should talk to the
admin of the load-balancer to make sure session stickyness is guaranteed
within one LDAP session.

Also load-balancers typically works ok for read access. But if your LDAP
client applications writes to a pool of dispatched LDAP servers probably
configured with multi-master replication you should read and understand
the implications in draft-zeilenga-ldup-harmful first.

http://tools.ietf.org/draft/draft-zeilenga-ldup-harmful/

If you're implementing a really heavy application you'd better do
load-balancing / fail-over within your application.

Ciao, Michael.