Chapter 20. Mounting file systems on demand

Procedure

1. Create a map file for the on-demand mount point, located at /etc/auto.identifier. Replace identifier with a name that identifies the mount point.
2. In the map file, enter the mount point, options, and location fields as described in The autofs configuration files section.
3. Register the map file in the master map file, as described in The autofs configuration files section.

4. Allow the service to re-read the configuration, so it can manage the newly configured autofs mount:

   # systemctl reload autofs.service

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5. Try accessing content in the on-demand directory:

   # ls automounted-directory

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Procedure

1. To configure LDAP access, modify the /etc/openldap/ldap.conf file. Ensure that the BASE and URI options are set to reflect the appropriate server and base for locating automount entries.

2. In the /etc/autofs.conf file configure the LDAP schema for automount maps. By default, autofs will check the commonly used schemas in the order given in the configuration file:

   #
   # Define the LDAP schema to used for lookups
   #
   # If no schema is set autofs will check each of the schemas
   # below in the order given to try and locate an appropriate
   # basdn for lookups. If you want to minimize the number of
   # queries to the server set the values here.
   #
   #map_object_class = nisMap
   #entry_object_class = nisObject
   #map_attribute = nisMapName
   #entry_attribute = cn
   #value_attribute = nisMapEntry
   #
   # Other common LDAP naming
   #
   #map_object_class = automountMap
   #entry_object_class = automount
   #map_attribute = ou
   #entry_attribute = cn
   #value_attribute = automountInformation
   #
   #map_object_class = automountMap
   #entry_object_class = automount
   #map_attribute = automountMapName
   #entry_attribute = automountKey
   #value_attribute = automountInformation

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   Note

   You can also set these values explicitly to marginally reduce LDAP queries. You can write the attributes in both lower and upper cases in the /etc/autofs.conf file.

3. The most recently established schema for storing automount maps in LDAP is described by the rfc2307bis draft. To use this schema, configure it in the /etc/autofs.conf file by uncommenting and setting the appropriate value for the ldap_schema option. For example, if you are using a non-standard schema or need to override the default behavior, you can specify the relevant schema attributes in the /etc/autofs.conf file. The following values correspond to commonly used schema settings such as those from the rfc2307bis draft:

   default_map_object_class = automountMap
   default_entry_object_class = automount
   default_map_attribute = automountMapName
   default_entry_attribute = automountKey
   default_value_atrribute = automountInformation

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   Note that the autofs automatically detects standard schemas, and specifying these settings is typically only necessary in custom or mixed-schema environments. If used, only one complete set of schema definitions should be active.

4. If you choose to specify a custom schema in the configuration, ensure that only one complete set of schema-related entries is active. Comment out any other to avoid conflicts. In the rfc2307bis schema, the automountKey attribute replaces the cn attribute used in the older rfc2307 schema. The following is an example of a corresponding LDAP Data Interchange Format (LDIF) configuration:

   # auto.master, example.com
   dn: automountMapName=auto.master,dc=example,dc=com
   objectClass: top
   objectClass: automountMap
   automountMapName: auto.master
   
   # /home, auto.master, example.com
   dn: automountMapName=auto.master,dc=example,dc=com
   objectClass: automount
   automountKey: /home
   automountInformation: auto.home
   
   # auto.home, example.com
   dn: automountMapName=auto.home,dc=example,dc=com
   objectClass: automountMap
   automountMapName: auto.home
   
   # foo, auto.home, example.com
   dn: automountKey=foo,automountMapName=auto.home,dc=example,dc=com
   objectClass: automount
   automountKey: foo
   automountInformation: filer.example.com:/export/foo
   
   # /, auto.home, example.com
   dn: automountKey=/,automountMapName=auto.home,dc=example,dc=com
   objectClass: automount
   automountKey: /
   automountInformation: filer.example.com:/export/&

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5. To allow authentication from an LDAP server, edit the /etc/autofs_ldap_auth.conf file:

   1. Change authrequired to yes.

   2. Set the principal to the Kerberos host principal for the LDAP server, host/FQDN@REALM. The principal name is used to connect to the directory as part of GSS client authentication:

      <autofs_ldap_sasl_conf
           usetls="no"
           tlsrequired="no"
           authrequired="yes"
           authtype="GSSAPI"
      clientprinc="host/server.example.com@EXAMPLE.COM"/>
           secret="<ldap password>"/>

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      For more information about host principal, see Using canonicalized DNS host names in IdM. You can also run klist -k to get the exact host principal information.

Procedure

1. Define the mount point and the local automount map by editing the /etc/auto.master file on the server where you want to mount user home directories, and add:

   /home /etc/auto.home

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2. Create the local automount map file /etc/auto.home on the server where you need to mount user home directories, and add:

   * -fstype=nfs,rw,sync host.example.com:/home/&

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   You can skip fstype parameter, as it is nfs by default. For more information, see autofs(5) man page on your system.

3. Reload the autofs service:

   # systemctl reload autofs

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Procedure

1. Add desired fstab entry as documented in Persistently mounting file systems. For example:

   /dev/disk/by-id/da875760-edb9-4b82-99dc-5f4b1ff2e5f4  /mount/point  xfs  defaults  0 0

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2. Add x-systemd.automount to the options field of entry created in the previous step.

3. Load newly created units so that your system registers the new configuration:

   # systemctl daemon-reload

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4. Start the automount unit:

   # systemctl start mount-point.automount

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Verification

1. Check that mount-point.automount is running:

   # systemctl status mount-point.automount

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2. Check that automounted directory has desired content:

   # ls /mount/point

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Procedure

1. Create a mount unit. For example:

   mount-point.mount
   [Mount]
   What=/dev/disk/by-uuid/f5755511-a714-44c1-a123-cfde0e4ac688
   Where=/mount/point
   Type=xfs

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2. Create a unit file with the same name as the mount unit, but with extension .automount.

3. Open the file and create an [Automount] section. Set the Where= option to the mount path:

   [Automount]
   Where=/mount/point
   [Install]
   WantedBy=multi-user.target

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4. Load newly created units so that your system registers the new configuration:

   # systemctl daemon-reload

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5. Enable and start the automount unit instead:

   # systemctl enable --now mount-point.automount

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Verification

1. Check that mount-point.automount is running:

   # systemctl status mount-point.automount

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2. Check that automounted directory has desired content:

   # ls /mount/point

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