Device configuration IDs

Device configuration IDs

The key names below the per-device-type definition maps (like ethernets:)
are called "ID"s. They must be unique throughout the entire set of
configuration files. Their primary purpose is to serve as anchor names for
composite devices, for example to enumerate the members of a bridge that is
currently being defined.

(Since 0.97) If an interface is defined with an ID in a configuration file; it will
be brought up by the applicable renderer. To not have netplan touch an interface
at all, it should be completely omitted from the netplan configuration files.

There are two physically/structurally different classes of device definitions,
and the ID field has a different interpretation for each:

Physical devices

(Examples: ethernet, modem, wifi) These can dynamically come and go between
reboots and even during runtime (hotplugging). In the generic case, they
can be selected by match: rules on desired properties, such as name/name
pattern, MAC address, driver, or device paths. In general these will match
any number of devices (unless they refer to properties which are unique
such as the full path or MAC address), so without further knowledge about
the hardware these will always be considered as a group.

It is valid to specify no match rules at all, in which case the ID field is
simply the interface name to be matched. This is mostly useful if you want
to keep simple cases simple, and it’s how network device configuration has
been done for a long time.

If there are match: rules, then the ID field is a purely opaque name
which is only being used for references from definitions of compound
devices in the config.

Virtual devices

(Examples: veth, bridge, bond) These are fully under the control of the
config file(s) and the network stack. I. e. these devices are being created
instead of matched. Thus match: and set-name: are not applicable for
these, and the ID field is the name of the created virtual device.

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