Automatically mount shared windows folders at boot on linux w/ systemd

cifs_automount.md

Automount of CIFS (smbfs) folders w/ systemd

i.e. mounting your Windows shares on Linux at boot

First, let's see how to mount the remote directory. Assume that there is a shared folder over the network at \\192.168.1.1\users\self\shared which is accessible with user myuser and password secret123.

We could mount it manually in /mnt/winshare with:

# mount -t cifs //192.168.1.1/users/self/shared /mnt/winshare -o user=myuser,password=secret123

This should work on your Linux box, because systemd will basically call mount with the same arguments: What (//192.168.1.1/users/self/shared), Where (/mnt/winshare) and Options (user=myuser,password=secret123).

To configure systemd to automatically mount that network folder on boot, there are 2 files needed: mnt-winshare.mount and mnt-winshare.automount. The .mount unit file specifies how to mount a drive (man systemd.mount for details), while the .automount unit file specifies what to mount automatically on boot (man systemd.automount).

Important! Note that the name of the file must map to the actual filesystem mount target, that is mnt-winshare.(auto)mount refers to /mnt/winshare. E.g. to mount in /home/user/myfolder the file names must be home-user-myfolder.(auto)mount.

The content of the files is the following:

# cat /etc/systemd/system/mnt-winshare.mount
[Unit]
Description=Remote Win Mount

[Mount]
What=//192.168.1.1/users/self/shared
Where=/mnt/winshare
Type=cifs
Options=user=myuser,password=secret123

[Install]
WantedBy=multi-user.target

and

# cat /etc/systemd/system/mnt-winshare.automount
[Unit]
Description=Automount Remote Win Mount

[Automount]
Where=/mnt/winshare

[Install]
WantedBy=multi-user.target

The former file goes in /etc/systemd/system/mnt-winshare.mount while the latter /etc/systemd/system/mnt-winshare.automount.

Then, reload the units to ensure everything is to its latest version:

# systemctl daemon-reload

At this point, we should be able to manually mount and unmount the remote folder using systemctl:

# systemctl start mnt-winshare.mount
# systemctl stop mnt-winshare.mount

This will not, however, automatically mount the system at startup. To do so, just enable the automount

# systemctl enable mnt-winshare.automount

And this should be it!

There's a slight difference between this method and /etc/fstab that's worth noting. Writing this here in case it helps others.
In fstab you need to escape and convert special characters to ascii, so if the share has a space in the name you need to include \040
if the share has an & in the name you need to use \046. This is not the case for the systemd method. In the Where= just put the literal string with special characters.

Another shoutout is how to manage paths on the local directory with a hyphen in the name, given the naming convention of the systemd .mount file replaces slashes with hyphens.

In this instance you want to use the ascii code for hyphen in the filename which is \x2d

So the path:
/mnt/my-windows-share
Becomes:
/etc/systemd/system/mnt-my\x2dwindows\x2dshare.mount

And a subsequent .automount file to match

You can either put the file in quotes when creating it, or double escape it
vi /etc/systemd/system/mnt-my\\x2dwindows\\x2dshare.mount or
vi "/etc/systemd/system/mnt-my\x2dwindows\x2dshare.mount"

For the correct name of the unit, you can use:
systemd-escape -p --suffix=mount '/media/offline@server/<user>

media-offline\x40server-\x3cuser\x3e.mount

If password contains comma ,, options can't be parsed if given Options=password=abc,123

Instead you can use credential file:

Options=cred=/path/to/cred-file

# cat /path/to/cred-file
username=user
password=abc,123