7.4. Package UDM hooks

For some purposes, for example for app installation, it is convenient to be able to deploy a new UDM hook in the UCS domain from any system in the domain. For this purpose, a UDM hook can be stored as a special type of UDM object. The module responsible for this type of objects is called settings/udm_hook. As these objects are replicated throughout the UCS domain, the UCS servers listen for modifications on these objects and integrate them into the local UDM.

The commands to create the UDM hook objects in UDM may be put into any join script (see Domain join). Like every UDM object a UDM hook object can be created by using the UDM command line interface univention-directory-manager or its alias udm. UDM hook objects can be stored anywhere in the LDAP directory, but the recommended location would be cn=udm_hook,cn=univention, below the LDAP base. Since the join script creating the attribute may be called on multiple hosts, it is a good idea to add the --ignore_exists option, which suppresses the error exit code in case the object already exists in LDAP.

The module settings/udm_hook requires several parameters. Since many of these are determined automatically by the ucs_registerLDAPExtension shell library function, it is recommended to use the shell library function to create these objects (see join.sh).

name (required)

Name of the UDM hook.

data (required)

The actual UDM hook data in bzip2 and base64 encoded format.

filename (required)

The filename the UDM hook data should be written to by the listening servers. The filename must not contain any path elements.

package (required)

Name of the Debian package which creates the object.

packageversion (required)

Version of the Debian package which creates the object. For object modifications the version number needs to increase unless the package name is modified as well.

appidentifier (optional)

The identifier of the app which creates the object. This is important to indicate that the object is required as long as the app is installed anywhere in the UCS domain. Defaults to string.

ucsversionstart (optional)

Minimal required UCS version. The UDM hook is only activated by systems with a version higher than or equal to this.

ucsversionend (optional)

Maximal required UCS version. The UDM hook is only activated by systems with a version lower than or equal to this. To specify validity for the whole 5.0-x release range a value like 5.0-99 may be used.

active (internal)

A boolean flag used internally by the Primary Directory Node to signal availability of the new UDM hook on the Primary Directory Node (default: FALSE).