Link Aliases

Learn how to provide alternative names for network interfaces.

Talos Linux by default names physical network interfaces based on predictable interface naming conventions (e.g., ens3, enp0s31f6, etc.). In some scenarios, it might be desirable to provide alternative, more user-friendly names for network interfaces. This can be achieved using LinkAliasConfig configuration documents.

Note:

• only physical links can be aliased (logical links like bridges, bonds, or VLANs are given user-defined names directly);
• link alias configuration document should match exactly one physical link, otherwise the configuration will not be applied;
• link alias can be used interchangeably with physical link names in all networking configuration sections (links, routes, addresses, etc.).

The link alias is built using a CEL expression running on the specfication of a LinkStatus resource:

# talosctl get linkstatus enp0s2 -o yaml
...
spec:
    altNames:
        - enxb6dce1a4a634
    index: 8
    type: ether
    linkIndex: 0
    flags: UP,BROADCAST,RUNNING,MULTICAST,LOWER_UP
    hardwareAddr: b6:dc:e1:a4:a6:34
    permanentAddr: b6:dc:e1:a4:a6:34
    broadcastAddr: ff:ff:ff:ff:ff:ff
    mtu: 1500
    queueDisc: pfifo_fast
    operationalState: up
    kind: ""
    slaveKind: ""
    busPath: "0000:00:02.0"
    driver: virtio_net
    driverVersion: 1.0.0
    productID: "0x1000"
    vendorID: "0x1af4"
    product: Virtio network device
    vendor: Red Hat, Inc.
    linkState: true
    speedMbit: 4294967295
    port: Other
    duplex: Unknown

The following example creates a link alias net0 for the only physical network interface found on the system:

apiVersion: v1alpha1
kind: LinkAliasConfig
name: net0
selector:
    match: true # as there is a single link only, we can match it this way

The following example creates a link alias mgmt for the network interface with a specific MAC address:

apiVersion: v1alpha1
kind: LinkAliasConfig
name: mgmt
selector:
    match: mac(link.permanent_addr) == "00:1a:2b:3c:4d:5e"

The aliases can be observed in the LinkStatus resources:

$ talosctl get links
NODE         NAMESPACE   TYPE         ID          VERSION   ALIAS   TYPE       KIND     HW ADDR                                           OPER STATE   LINK STATE
172.20.0.2   network     LinkStatus   enp0s2      4         net0    ether               b6:dc:e1:a4:a6:34                                 up           true
...

In the above example, the physical interface enp0s2 has been aliased to net0, which can now be used in all networking configuration sections.

To see all aliases produced from the machine configuration, use the following:

$ talosctl get linkaliasspec
NODE         NAMESPACE   TYPE            ID       VERSION   ALIAS
172.20.0.2   network     LinkAliasSpec   enp0s2   1         net0