Convert an fstab entry to a systemd mount unit on CoreOS

coreossystemd

I want to convert the following fstab entry to a systemd mount unit on CoreOS,

/dev/xvdb /data ext4 defaults,auto,noatime,noexec 0 0

I created data.mount,

[Unit]
Description=MongoDB Data Directory

[Mount]
What=/dev/xvdb
Where=/data
Type=ext4
Options=defaults,auto,noatime,noexec 0 0

However, I had to remove 0 0 because the unit failed to start.

[Unit]
Description=MongoDB Data Directory

[Mount]
What=/dev/xvdb
Where=/data
Type=ext4
Options=defaults,auto,noatime,noexec

The unit above starts, but I'm not sure about the Options= string. Reading about the fstab options I wonder if some are redundant.

According to Ubuntu Fstab – Community Help Wiki

auto – The filesystem can be mounted automatically (at bootup, or when
mount is passed the -a option). This is really unnecessary as this is
the default action of mount -a anyway.

defaults – Use default settings. Equivalent to rw, suid, dev, exec,
auto, nouser, async.

This leads me to the following unit,

[Unit]
Description=MongoDB Data Directory

[Mount]
What=/dev/xvdb
Where=/data
Type=ext4
Options=defaults,noatime,noexec

Is this the proper way to create a mount unit using systemd on CoreOS?

Best Answer

defaults is redundant. When any other options are in use, it can be omitted. It only exists to fill the relevant column in fstab.

And since auto is already a default, it too is redundant.

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