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Re: Replicate cn=config between masters and slaves?

Christian Kratzer wrote:

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.
One of the changes that has been waiting in the wings for a long time is to move syncrepl config out of the olcDatabase entry and into its own olcOverlay entry. At that point a lot of config needs will make a lot more sense, and there'll be no need for gyrations of shared/merged config. 


3. How to best handle backward compatibility.
We've done this transition once before, changing backglue/subordinate from a database keyword into its own overlay. I don't think it will present any special problems. 

--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/