Disable reverse path filter on Calico interfaces

The reverse path filtering is enabled on the interfaces managed
by Calico. The filter would drop packets if the return path
is not symmetrical to the ingress path.
This commit disables the reverse path filtering on tunl0 interface
to allow asymmetrical routing.

Closes-Bug: 1838801

Change-Id: Iee52f7860770983f9ced8b88ceabbccdf41e4131
Signed-off-by: Teresa Ho <teresa.ho@windriver.com>

playbookconfig/src/playbooks/bootstrap/roles/bringup-essential-services/templates/calico-cni.yaml.j2

@@ -700,6 +700,13 @@ spec:
               - -bird-ready
               - -felix-ready
             periodSeconds: 10
+          {% if cluster_network_ipv4 -%}
+          # Disable reverse path filter for tunl0 interface
+          lifecycle:
+            postStart:
+              exec:
+                command: ["/bin/sh", "-c", "sysctl -w net.ipv4.conf.tunl0.rp_filter=0"]
+          {% endif -%}
           volumeMounts:
             - mountPath: /lib/modules
               name: lib-modules