!!! Overview
There are three [LDAP Schemas] that can be used for storing [autofs] [data] in [LDAP].
They do not differ in semantics the way [RFC2307|RFC2307Schema] and [RFC2307bis|SchemaRFC2307Bis] schemas differ in the member/memberuid attribute. The difference in schemas is mostly attribute and [ObjectClasses] naming and how the [DNs] are constructed. The [DNs] are also not used by the [NIX] [client].
[SSSD] should convert the data into a cache-specific schema. The cache specific schema will be based on the RFC2307bis automounter schema, which is by far the most widely used schema.
Each of the schemas define objectclass names for map and entry and attribute names for map name (used by map) and key and value attribute names (used by map entry).
%%zebra-table
%%sortable
%%table-filter
|| [attribute] || [RFC2307bis|SchemaRFC2307Bis] ||[NIS]||[RFC2307Schema] extension
| map objectclass | [automountMap]| [nisMap]| [automountMap]
| entry objectclass|[automount]| [nisObject]| [automount]
| map attribute | [automountMapName]| [nisMapName] | [ou]
| entry attribute| [automountKey]| [cn] | [cn]
| value attribute| [automountInformation] | [nisMapEntry] | [automountInformation] |
/%
/%
/%
An example of the [RFC2307bis|SchemaRFC2307Bis] [LDAP Schema] showing an entry for /home/foo included in the master map:
{{{
dn: automountMapName=auto.master,dc=example,dc=com
objectClass: top
objectClass: automountMap
automountMapName: auto.master
dn: automountMapName=auto.master,dc=example,dc=com
objectClass: automount
cn: /home
automountKey: /home
automountInformation: auto.home
dn: automountMapName=auto.home,dc=example,dc=com
objectClass: automountMap
automountMapName: auto.home
dn: automountKey=foo,automountMapName=auto.home,dc=example,dc=com
objectClass: automount
automountKey: foo
automountInformation: filer.example.com:/export/foo
}}}
Most, if not all, of the [autofs] documentation out there describes the naming schema as per [RFC2307bis|SchemaRFC2307Bis], but it is technically possible to use [autofs] objects created according to [RFC2307bis|SchemaRFC2307Bis] and user/group objects created according to plain [RFC 2307] in the same [DIT]. Because the schemas differ in attribute naming only, not semantically, it is trivial to override the schema in the config file.
One difference between [File System] entries and entries in [LDAP] is that the [cn] attribute is [Case-insensitive], unlike key names which are essentially directory names. This seems to be one of the reasons the [RFC2307bis|SchemaRFC2307Bis] schema was adopted.
nsswitch.conf is automounter: ldap (there is no /etc/auto.master file)
Sample ldif for auto.master and auto.home entries
{{{
dn: ou=auto.master, dc=mydom,dc=com
ou: auto.master
objectClass: top
objectClass: automountMap
dn: cn=/home,ou=auto.master, dc=mydom,dc=com
objectClass: automount
automountInformation: ldap:host.mydom.com:ou=auto.home,dc=mydom,dc=com --timeout 60
cn: /home
dn: ou=auto.home, dc=mydom,dc=com
ou: auto.home
objectClass: top
objectClass: organizationalUnit
dn: cn=user1,ou=auto.home, dc=mydom,dc=com
objectClass: automount
automountInformation: -rw,hard,intr host:/export/home/user1
cn: user1
}}}
In this senario, when the automounter starts, it will parse the [nsswitch.conf] file. Since our entry contains [LDAP] it will search the base dn specified in the /etc/ldap.conf file for the [objectClass]: [automount] with the ou=auto.master and use the automountinformation entry as a pointer to rest of the mount information as in the example [LDIF] above.
Automounts become a DIT structure similar to:
{{{
dc=com
|--dc=willeke
|---ou=Unix
|----automountMapName=auto_direct
|-----automountKey=/mnt_direct/test1
|-----automountKey=/mnt_direct/test2
}}}
!! The nisObject Automount [RFC2307Schema]
The nisObject automount schema defines nisMap and nisObject structures to represent the AutoFS maps and their entries. The AutoFS maps are stored in the LDAP directory server using the [nisMap] and [nisObject] structures.
An Example
The following shows an example of a direct AutoFS map, auto_direct, stored in the LDAP directory server using the nisObject automount schema:
{{{
dn:nisMapName=auto_direct,dc=nishpind
objectClass: top
objectClass: nisMap
nisMapName: auto_directdn:cn=/mnt_direct/test1, nisMapName=auto_direct, dc=nishpind
objectClass: top
objectClass: nisObject
nisMapName: auto_direct
cn: /mnt_direct/test1
nisMapEntry:hostA:/tmp
dn:cn=/mnt_direct/test2, nisMapname=auto_direct, dc=nishpind
objectClass: top
objectClass: nisObject
nisMapName: auto_direct
cn: /mnt_direct/test2
nisMapEntry:hostB:/tmp
}}}
!! Limitations
The [nisObject] automount schema contains three attributes:
* cn
* nisMapEntry
* nisMapName.
cn is an attribute that ignores case-matching. Consider the following example:
{{{
# an indirect map named auto_test
test1 server1:/source
TEST1 server2:/source
}}}
In the above example, because the cn attribute is [case-insensitive], the [LDAP] considers:
* cn=TEST1, nisMapName=auto_test
* cn=test1, nisMapName=auto_test
these entries the same.
Using the [nisObject] [automount] map schema, __capital letters are not significant__. In other words, if two keys have names that are only different by the use of capital letters, then one of those entries will be rendered inoperable because the other one is the only one that can be retrieved.
NOTE: If you use the nisObject [automount] map schema, do not use any keys that have capital letters and only differ from other keys by those capital letters.
!! [nsswitch.conf]
[nsswitch.conf] is automounter as this is NOT in [LDAP] (i.e. there is no /etc/auto.master file)
!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]
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* [#1] - [The LDAP schema used by autofs|https://docs.pagure.org/SSSD.sssd/design_pages/autofs_integration.html#the-ldap-schema-used-by-autofs|target='_blank'] - based on information obtained 2020-02-19