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Re: Replicate cn=config between masters and slaves?

Hi,

On Mon, 16 Dec 2013, Howard Chu wrote:

Christian Kratzer wrote:

Hi,

On Mon, 16 Dec 2013, Karsten Heymann wrote:

Hi,

when setting up a cluster with 1+x masters and 1+x slaves, is it possible
to use a single cn=config replicated between all of these? Or do masters
and slaves need to have different settings anyhow. I'd like not to have to
manage schema information and acls in two places.


as you generally tend to have slightly different settings on masters and
slaves there is currently no other way byt to have separate sets of cn=config 
for masters and slaves.


Use syncrepl suffixmassage. Read this thread.
http://www.openldap.org/lists/openldap-technical/201104/msg00206.html


interesting. I never noticed that. One still has to keep full parallel
copies of different cn=config variations.

I had been thinking about a schmeme of having additional attributes under cn=config
that would specify to which servers they apply using their respective server URI.

Something like the following:

    dn: olcDatabase=mdb,cn=config
    objectClass: olcDatabaseConfig
    objectClass: olcMdbConfig
    olcDatabase: mdb
    olcDbDirectory: /var/lib/ldap
    olcSuffix: dc=example,dc=org

    dn: cn=master-subconfig,olcDatabase=mdb,cn=config
    objectClass: olcDatabaseConfig
    objectClass: olcMdbConfig
    objectClass: xxxServerConfig
    olcDatabase: mdb
    xxxServerConfigURI: ldap://ldap-master-1
    xxxServerConfigURI: ldap://ldap-master-2
    olcSyncrepl: id=1 provider=ldap://ldap-master-1 ...
    olcSyncrepl: id=2 provider=ldap://ldap-master-2 ...
    olcMirrorMode: TRUE

    dn: cn=slave-subconfig,olcDatabase=mdb,cn=config
    objectClass: olcDatabaseConfig
    objectClass: olcMdbConfig
    objectClass: xxxServerConfig
    olcDatabase: mdb
    xxxServerConfigURI: ldap://ldap-slave1
    xxxServerConfigURI: ldap://ldap-slave2
    olcSyncrepl: id=1 provider=ldap://ldap-master-1 ...
    olcSyncrepl: id=2 provider=ldap://ldap-master-2 ...
    olcMirrorMode: FALSE

that would allow one put site wide shared defaults into the parent entry
and group servers with differences under subentries.

Above example has the same provider specs on masters and slaves but I
would like to build larger clusters where they would perhaps differ on
each group of servers.

I would expect to merge shared and specific configuration on each host.

Would such a proposal be interesting as a feature request ?

Several open points would need to be solved though:

1. How to cope with the top level cn=config entry.

2. How to handle cases where for example olcDbDirectory is enforced as MUST
   in the schema for olcMdbConfig and we only define it in the parent entry
   but default it in the slaves.

   That is do we need to repeat MUST attributes on every config item.

3. How to best handle backward compatibility.

...


Greetings
Christian

--
Christian Kratzer                      CK Software GmbH
Email:   ck@cksoft.de                  Wildberger Weg 24/2
Phone:   +49 7032 893 997 - 0          D-71126 Gaeufelden
Fax:     +49 7032 893 997 - 9          HRB 245288, Amtsgericht Stuttgart
Web:     http://www.cksoft.de/         Geschaeftsfuehrer: Christian Kratzer