Systemd - Mount filesystems on demand

I find myself using systemd's built-in functions more and more. This time, automounts and mounts which I prefer to autofs due to systemd-automount's simplicity.

Talking about simplicity, all it takes for a automount is a unit-file (.automount), reloading the systemd daemon and enable the automount unit.

Here's a quick reference on how to set it up using a nfs-share but keep in mind that automounts work with pretty much any other filesystem aswell.

Ensure a nfs-share exists on your nfs server (any nfs-server will do):

 [root@nfs ~]# cat << EOF >> /etc/exports  
 /var/nfs/data server.archyslife.lan(rw,secure,sync,no_root_squash,nohide)  
 EOF

On the server that's going to be mounting the share, create the systemd-mount unit first:

 [root@server ~]# cat << EOF > /etc/systemd/system/var-backup-data.mount    
 [Unit]  
 Description=Mount for /var/backup/data  
 [Mount]  
 What=nfs.archyslife.lan:/var/nfs/data  
 Where=/var/backup/data  
 Type=nfs  
 Options=rw,vers=4.2,sec=sys,soft,relatime,namlen=255,timeo=30,retry=3,retrans=3,proto=tcp,_netdev  
 EOF

Test if the mount is working as expected:

 [root@server ~]# systemctl daemon-reload  
 [root@server ~]# systemctl start var-backup-data.mount  
 [root@server ~]# systemctl status var-backup-data.mount

If the mount unit itself worked as expected, stop the mount and continue to with the automount unit:

 [root@server ~]# systemctl stop var-backup-data.mount
 [root@server ~]# cat << EOF > /etc/systemd/system/var-backup-data.automount  
 [Unit]  
 Description=Automount for /var/backup/data  
 After=network.target  
 [Automount]  
 Where=/var/backup/data  
 DirectoryMode=0755  
 TimeoutIdleSec=30  
 [Install]  
 WantedBy=multi-user.target  
 EOF

Reload systemd and enable the automount unit:

 [root@server ~]# systemctl daemon-reload  
 [root@server ~]# systemctl enable --now var-backup-data.automount

Now let's get to testing:

 [root@server ~]# dd if=/dev/zero of=/var/backup/data/test bs=512K count=1000 status=progress

Check if the directory has been mounted on access:

 [root@server ~]# findmnt /var/backup/data  
 [root@server ~]# systemctl status var-backup-data.automount var-backup-data.mount

Success, the directory '/var/backup/data' was automatically mounted when it was accessed and the data has been written to it.

Feel free to comment and / or suggest a topic.

Comments

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