Chapter 22. Introduction to Nmstate

The libnmstate Python library enables developers to use Nmstate in their own application

To use the library, import it in your source code:

import libnmstate

Note that you must install the nmstate and python3-libnmstate packages to use this library.

import libnmstate
from libnmstate.schema import Interface

net_state = libnmstate.show()
for iface_state in net_state[Interface.KEY]:
    print(iface_state[Interface.NAME] + ": "
          + iface_state[Interface.STATE])

You can use the nmstatectl utility to store the current network configuration of one or all interfaces in a file. You can then use this file to:

For example, you can export the settings of the enp1s0 interface to a file, modify the configuration, and apply the settings to the host.

You can automatically apply new network settings when the Red Hat Enterprise Linux system boots by configuring the nmstate systemd service.

With the nmstate package installed, you can store *.yml files with Nmstate instructions in the /etc/nmstate/ directory. The nmstate service then automatically applies the files on the next reboot or when you manually restart the service. After Nmstate successfully applies a file, it renames the file’s .yml suffix to .applied to prevent the service from processing the same file again.

The nmstate service is a oneshot systemd service. Consequently, systemd executes it only when the system boots and when you manually restart the service.

The network RHEL system role supports state configurations in playbooks to configure the devices. For this, use the network_state variable followed by the state configurations.

Benefits of using the network_state variable in a playbook:

For example, to create an Ethernet connection with dynamic IP address settings, use the following vars block in your playbook:

vars:
  network_state:
    interfaces:
    - name: enp7s0
      type: ethernet
      state: up
      ipv4:
        enabled: true
        auto-dns: true
        auto-gateway: true
        auto-routes: true
        dhcp: true
      ipv6:
        enabled: true
        auto-dns: true
        auto-gateway: true
        auto-routes: true
        autoconf: true
        dhcp: true

vars:
  network_connections:
    - name: enp7s0
      interface_name: enp7s0
      type: ethernet
      autoconnect: yes
      ip:
        dhcp4: yes
        auto6: yes
      state: up

For example, to only change the connection status of dynamic IP address settings that you created as above, use the following vars block in your playbook:

vars:
  network_state:
    interfaces:
    - name: enp7s0
      type: ethernet
      state: down

vars:
  network_connections:
    - name: enp7s0
      interface_name: enp7s0
      type: ethernet
      autoconnect: yes
      ip:
        dhcp4: yes
        auto6: yes
      state: down