Make ip route add and ip rule add commands persistent on startup

I need to make the below two lines persistent so that they are available on server reboot now that I have proved that the route and the rules works as expected on AlmaLinux 8 (AlmaLinux is basically the same as CentOS)

ip route add default via x.x.x.x dev eno5 src x.x.x.x table 1
ip rule add from x.x.x.x table 1

Everything I've seen shows I should be able to create a file in /etc/sysconfig/network-scripts/route-eno5 and the default via x.x.x.x dev eno5 src x.x.x.x table 1 and /etc/sysconfig/network-scripts/route-eno5 and add the line from x.x.x.x table 1 but when I save this and reboot those rules are not applied.

Is this not supported on AlmaLinux 8 and done in a different or am I doing something wrong?

RHEL 8 and later -- and all derived distributions, like CentOS and AlmaLinux -- no longer use the legacy /etc/sysconfig/network-scripts directory. The correct solution is to modify the NetworkManager configuration.

NetworkManager can add both static routes and policy routing rules. There is some relevant documentation here.

On a default CentOS 8(stream) install, my NetworkManager configuration looks like this:

[root@localhost ~]# nmcli c show
NAME         UUID                                  TYPE      DEVICE
System eth0  5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03  ethernet  eth0

If I want to add a policy route to eth0, I would do something like this:

nmcli c mod 'System eth0' \
  ipv4.addresses 10.0.0.10/24 \
  ipv4.routes '0.0.0.0/0 10.0.0.1 table=1' \
  ipv4.route-rules 'priority 100 from 10.0.0.0/24 table 1'

In this example I'm adding a static ip addresses that is different from the one that gets assigned dynamically using DHCP; this may not be necessary in your situation depending on what your local configuration looks like.

After restarting the interface:

nmcli c down 'System eth0'; nmcli c up 'System eth0'

I now have:

[root@localhost ~]# ip addr show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 52:54:00:c1:f0:62 brd ff:ff:ff:ff:ff:ff
    inet 10.0.0.10/24 brd 10.0.0.255 scope global noprefixroute eth0
       valid_lft forever preferred_lft forever
    inet 192.168.122.164/24 brd 192.168.122.255 scope global dynamic noprefixroute eth0
       valid_lft 3505sec preferred_lft 3505sec
    inet6 fe80::5054:ff:fec1:f062/64 scope link
       valid_lft forever preferred_lft forever

[root@localhost ~]# ip rule show
0:      from all lookup local
100:    from 10.0.0.0/24 lookup 1
32766:  from all lookup main
32767:  from all lookup default

[root@localhost ~]# ip route show table 1
default via 10.0.0.1 dev eth0 proto static metric 100
10.0.0.1 dev eth0 proto static scope link metric 100

You can use "NetworkManager Text User Interface" (nmtui tool)

# yum install NetworkManager-tui

# nmtui

Go to Edit a connection, select connection... Add routes in Routing section.