Enhancement: Improved UPF routing and NAT handling

roles/router/tasks/install.yml

@@ -1,5 +1,3 @@
----
-
 # TODO: running on master node for now (fix to run on multiple nodes)
 
 - set_fact:
@@ -95,10 +93,12 @@
   when: inventory_hostname in groups['master_nodes']
   become: true
 
-- name: copy aether-ue-nat.service to {{ systemd_system_dir }}/aether-ue-nat.service
+# Use Jinja template for `aether-ue-nat.service`
+- name: Generate aether-ue-nat.service dynamically
   template:
-    src: roles/router/templates/systemd/aether-ue-nat.service
+    src: roles/router/templates/systemd/aether-ue-nat.service.j2
     dest: "{{ systemd_system_dir }}/aether-ue-nat.service"
+    mode: "0644"
   when: inventory_hostname in groups['master_nodes']
   become: true
 
@@ -122,7 +122,7 @@
   when: inventory_hostname in groups['master_nodes']
   become: true
 
-- name: restart systemd-networkd
+- name: Restart systemd-networkd
   systemd:
     name: systemd-networkd
     state: restarted

roles/router/templates/systemd/aether-ue-nat.service.j2

@@ -0,0 +1,20 @@
+# Copyright 2022-present Open Networking Foundation
+# SPDX-License-Identifier: Apache-2.0
+
+[Unit]
+Description=Aether UE NAT Setup
+After=network.target
+
+[Service]
+Type=oneshot
+ExecStart=/bin/bash -c "\
+    sudo iptables -t nat -C POSTROUTING -s {{ core.upf.default_upf.ue_ip_pool }} -o {{ core.data_iface }} -j MASQUERADE || \
+    sudo iptables -t nat -A POSTROUTING -s {{ core.upf.default_upf.ue_ip_pool }} -o {{ core.data_iface }} -j MASQUERADE; \
+    {% for upf_key, upf_data in core.upf.additional_upfs.items() %} \
+    sudo iptables -t nat -C POSTROUTING -s {{ upf_data.ue_ip_pool }} -o {{ core.data_iface }} -j MASQUERADE || \
+    sudo iptables -t nat -A POSTROUTING -s {{ upf_data.ue_ip_pool }} -o {{ core.data_iface }} -j MASQUERADE; \
+    {% endfor %} \
+"
+
+[Install]
+WantedBy=sys-subsystem-net-devices-core.device

roles/upf/tasks/install.yml

@@ -54,8 +54,8 @@
 
 - name: configure route for upf traffic on gnbsim node
   shell: |
+    ip route show | grep -q "{{ item.value.ue_ip_pool }} via {{ item.value.ip.core }}" || \
     ip route add {{ item.value.ue_ip_pool }} via {{ item.value.ip.core }}
   when: inventory_hostname in groups['master_nodes']
   with_dict: "{{ core.upf.additional_upfs}}"
   become: true
-  # ignore_errors: yes