Implement ECMP for unsafe_routes (#1332)

examples/config.yml

@@ -239,7 +239,28 @@ tun:
 
   # Unsafe routes allows you to route traffic over nebula to non-nebula nodes
   # Unsafe routes should be avoided unless you have hosts/services that cannot run nebula
-  # NOTE: The nebula certificate of the "via" node *MUST* have the "route" defined as a subnet in its certificate
+  # Supports weighted ECMP if you define a list of gateways, this can be used for load balancing or redundancy to hosts outside of nebula
+  # NOTES:
+  # * You will only see a single gateway in the routing table if you are not on linux
+  # * If a gateway is not reachable through the overlay another gateway will be selected to send the traffic through, ignoring weights
+  #
+  # unsafe_routes:
+  # # Multiple gateways without defining a weight defaults to a weight of 1, this will balance traffic equally between the three gateways
+  # - route: 192.168.87.0/24
+  #   via:
+  #     - gateway: 10.0.0.1
+  #     - gateway: 10.0.0.2
+  #     - gateway: 10.0.0.3
+  # # Multiple gateways with a weight, this will balance traffic accordingly
+  # - route: 192.168.87.0/24
+  #   via:
+  #     - gateway: 10.0.0.1
+  #       weight: 10
+  #     - gateway: 10.0.0.2
+  #       weight: 5
+  #
+  # NOTE: The nebula certificate of the "via" node(s) *MUST* have the "route" defined as a subnet in its certificate
+  # `via`: single node or list of gateways to use for this route
   # `mtu`: will default to tun mtu if this option is not specified
   # `metric`: will default to 0 if this option is not specified
   # `install`: will default to true, controls whether this route is installed in the systems routing table.