community.general.nmcli: Add support for loopback type

[baxeno]

Summary

I am trying to add multiple IP addresses to loopback interface (lo). NetworkManager has treated loopback interfaces as unmanaged in the past but with version 1.42 (RHEL 9 / CentOS Stream 9) support for management was added. This was added by Red Hat to support a customer case who wanted to change MTU and additionally IP addresses, DNS, route and routing rules for the loopback connection profiles.

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/1332

Issue Type

Feature Idea

Component Name

nmcli

Additional Information

Normally the loopback interface is unmanaged by NetworkManager (nmcli) like below:

lo: connected (externally) to lo
        "lo"
        loopback (unknown), 00:00:00:00:00:00, sw, mtu 65536
        inet4 127.0.0.1/8
        inet6 ::1/128
        route6 ::1/128 metric 256

I want to change the loopback interface to be managed by NetworkManager and add more IP addresses to it like this:

lo: connected to lo
        "lo"
        loopback (unknown), 00:00:00:00:00:00, sw, mtu 65536
        inet4 127.0.0.7/32
        inet4 127.0.0.6/32
        inet4 127.0.0.5/32
        inet4 127.0.0.4/32
        inet4 127.0.0.3/32
        inet4 127.0.0.2/32
        inet4 127.0.0.1/8
        inet6 ::1/128

Can be done with the following command manually:

sudo nmcli con add type loopback con-name lo ifname lo ipv4.method manual ipv4.addresses 127.0.0.2/32,127.0.0.3/32,127.0.0.4/32,127.0.0.5/32,127.0.0.6/32,127.0.0.7/32

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Files identified in the description:

• plugins/modules/nmcli.py

If these files are incorrect, please update the component name section of the description or use the !component bot command.

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[ansibullbot]

cc @alcamie101
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[anp135]

You can quick patch for basic support loopback type

@@ -70,7 +70,7 @@
            - If you want to control non-ethernet connection attached to V(bond), V(bridge), or V(team) consider using O(slave_type) option.
        type: str
        choices: [ bond, bond-slave, bridge, bridge-slave, dummy, ethernet, generic, gre, infiniband, ipip, macvlan, sit, team, team-slave, vlan, vxlan,
            wifi, gsm, wireguard, vpn ]
            wifi, gsm, wireguard, vpn, loopback ]
    mode:
        description:
            - This is the type of device or network connection that you wish to create for a bond or bridge.
@@ -2400,6 +2400,7 @@ def main():
                          'macvlan',
                          'wireguard',
                          'vpn',
                          'loopback',
                      ]),
            ip4=dict(type='list', elements='str'),
            gw4=dict(type='str'),