389ds-replication

Configure replication between 389DS server (LDAP server) instances.

ansible-galaxy install lvps.389ds_replication

Requirements

• Ansible version: 2.7 or higher
• OS: CentOS 7

If Ansible does not support the ldap_attrs module you're using an old version of collections, but you can try version 1.0.x of this role.

Role Variables

Variable	Default	Description	Can be changed	Role
dirsv_replication_role		Role of this server: 'supplier', 'consumer' or 'both' (master). Hub is not supported.	No
dirsrv_server_uri	"ldap://localhost"	URI of the server to configure. Since this runs on the Ansible target, localhost should be fine. It's possible to set it to ldaps://localhost to use TLS on port 636.		CSB
dirsrv_rootdn	"cn=Directory Manager"	Root DN ("administrator" account username)		CSB
dirsrv_rootdn_password	secret	Password for root DN account		CSB
dirsrv_use_starttls	true	Use StartTLS to connect to the server		CSB
dirsrv_tls_certificate_trusted	true	True if TLS certificate is from a trusted CA, false if self-signed or from a private CA, unused if TLS is not used		CSB
dirsrv_serverid	default	Server ID aka instance ID, e.g. if the server is installed in the dirsrv/slapd-example directory, "example" is the server ID		CSB
dirsrv_suffix	dc=example,dc=local	Root suffix		CSB
dirsrv_supplier_replica_id	1	Choose a number between 1 and 65534. Don't assign it to other servers or bad things may happen.	No	SB
dirsrv_consumer_uri	"ldap://consumer.example.com:389/"	Full URI, including port, that the supplier will connect to and perform replication by pushing changes	No	SB
dirsrv_replication_user_remote	Replication Manager	User account that exists on the consumer. The supplier will bind with this account to perform replication. "Replication Manager" means that the account is "cn=Replication Manager,cn=config"	Yes	SB
dirsrv_replication_user_password_remote		Password for the replication user (Replication Manager) account	Yes	SB
dirsrv_replica_bind_method	"PLAIN"	Bind method that supplier uses to connect to the consumer (SIMPLE, PLAIN, SASL)	Yes	SB
dirsrv_changelog_max_age	"10d"	Sets the value of nsslapd-changelogmaxage	Yes	SB
dirsrv_replica_attributes_list	"(objectclass=*) $ EXCLUDE authorityRevocationList accountUnlockTime memberof"	Sets the value of nsds5ReplicatedAttributeList, the default of this variable is use throughout examples in the documentation	Yes	SB
dirsrv_replica_attributes_list_total	"(objectclass=*) $ EXCLUDE accountUnlockTime"	Sets the value of nsds5ReplicatedAttributeListTotal, the default of this variable is use throughout examples in the documentation	Yes	SB
dirsrv_replication_user	Replication Manager	User account to create on the consumer. This account will be used by the supplier to bind on this server (the consumer). "Replication Manager" means that the account will be created at "cn=Replication Manager,cn=config"	Yes	CB
dirsrv_replication_user_password		Password for that account.	Yes	CB
dirsrv_begin_replication_immediately	true	Boolean, sets nsds5ReplicaEnabled to "on" or "off" in the replication agreement. This should be a safe: if you add a new server it won't start pushing its empty database to other servers in any case because they have a different generation ID and replication fails (see examples for more details), but if you want to be even safer or make some customizations to the replication agreement, set this to false	No	CB
dirsrv_consumer_referral_to_supplier	"ldap://supplier.example.com:389/"	Full LDAP URI including port. When a client tries to write to a consumer, which is read-only, it will redirect the client to this server (a supplier that can accept writes).	Yes	C

First of all choose if the server is a supplier, consumer or both and set dirsv_role accordingly. Then set the variables related to that: look in the Role column, C = Consumer, S = Supplier, B = Both.

Some variables cannot be changed once they are set, changing them will produce unexcpected results ranging from "nothing happens" to "the role fails". Some others (authentication details, suffix, etc...) should be set to the correct value for the server, can be changed as long as that makes sense, i.e. you can change dirsrv_rootdn_password if you've changed the root DN password so that this role can authenticate correctly, but changing dirsrv_suffix between one run and the other on the same server is pointless, unless you somehow managed to change the suffix in 389DS.

The following variables have the exact same name and meaning as in the 389ds-server role, so if you're using both roles in the same playbook you can define them just once:

• dirsrv_rootdn

• dirsrv_rootdn_password

• dirsrv_tls_certificate_trusted
• dirsrv_serverid
• dirsrv_suffix

Dependencies

None.

But do keep in mind that this role expects 389DS to be already up and running, it only configures replication between existing servers.

Example Playbook

More examples, including 389DS installation from the ground up and the needed Vagrant configs to test them are available in the 389ds-examples repository.

Note that, usually, replication doesn't start immediately because the "replica generation" is different between the servers. This can be fixed with the "replica refresh" procedure, which is described for example in section 15.2.5 of the Administration Guide. You will need to perform it on suppliers or servers with role "both".

Basically, doing a "replica refresh" will forcefully push the database from one supplier to a consumer, replacing the previous consumer database: do this starting from one supplier and gradually moving toward the others, being careful to not replace a production database with the empty database of a server that has just been installed. When two servers have the exact same database, replication starts automatically and immediately.

The procedure is also exaplained in more details in the 389ds-examples repository.

Consumer and supplier

Configure the consumer first, this server will contain a read-only copy of the database:

- hosts: consumer
  become: true

  roles:
    -
      role: lvps.389ds_replication
      dirsrv_replica_role: consumer
      dirsrv_suffix: "dc=example,dc=local"
      dirsrv_server_uri: "ldap://localhost"
      dirsrv_rootdn_password: secret
      dirsrv_replication_user_password: foo # Will create cn=Replication Manager,cn=config with this password
      dirsrv_consumer_referral_to_supplier: "ldap://supplier.example.local:389/"

The configure the supplier, this server will accept writes and push all changes to the consumer:

- hosts: supplier
  become: true

  roles:
    -
      role: lvps.389ds_replication
      dirsrv_replica_role: supplier
      dirsrv_suffix: "dc=example,dc=local"
      dirsrv_server_uri: "ldap://localhost"
      dirsrv_rootdn_password: verysecret
      dirsrv_replication_user_password_remote: foo # Will bind with cn=Replication Manager,cn=config and this password on the other server
      dirsrv_consumer_uri: "ldap://consumer.example.local:389/" # The other server (the consumer defined above)
      dirsrv_supplier_replica_id: 123

Multi-master with two masters

- hosts: mm1
  become: true
  roles:
    -
      role: lvps.389ds_replication
      dirsrv_replica_role: 'both'
      dirsrv_suffix: "dc=example,dc=local"
      dirsrv_server_uri: "ldap://localhost"
      dirsrv_rootdn_password: secret1
      dirsrv_replication_user_password: "aaaaaa"
      dirsrv_replication_user_password_remote: "bbbbbb" # On the other server
      dirsrv_consumer_uri: "ldap://mm2.example.local:389/" # The other server
      dirsrv_supplier_replica_id: 1

- hosts: mm2
  become: true
  roles:
    -
      role: lvps.389ds_replication
      dirsrv_replica_role: 'both'
      dirsrv_suffix: "dc=example,dc=local"
      dirsrv_server_uri: "ldap://localhost"
      dirsrv_rootdn_password: secret2
      dirsrv_replication_user_password: "bbbbbb"
      dirsrv_replication_user_password_remote: "aaaaaa" # On the other server
      dirsrv_consumer_uri: "ldap://mm1.example.local:389/" # The other server
      dirsrv_supplier_replica_id: 2

Known bugs

If dirsrv_replication_user_password is changed, no change is reported: this is because password actually changes on every run (Ansible can't tell if the previous hashed password is the same as the new one, so it will be changed and hashed again), but there's a changed_when: false to hide that detail.

License

MIT.