Immutable Root Filesystem

The immutable rootfs concept in Elemental is provided by a dracut module. By default, elemental and derivatives will inherit an immutable setup.

A running system will look like as follows:

/usr/local - persistent (COS_PERSISTENT)
/oem - persistent (COS_OEM)
/etc - ephemeral
/usr - read only
/ immutable

This means that any changes that are not specified as cloud-init configuration are not persisting across reboots.

You can place persisting cloud-init files either in /oem or /usr/local/oem, Elemental already supports cloud-init datasources, so you can use also load cloud-init configuration as standard userdata, depending on the platform. For more details on the cloud-init syntax, see the cloud-init configuration reference.