networkd: Add support for multiple [Route] sections (#1868)

Networkd supports multiple [Route] sections within the same file.
Currently all [Route] section tags are squashed into one and if there
is a default gateway it means defining a device route is not possible
as the target is set to the default gateway.

This patch adds support for multiple [Route] sections allowing us to
support device routes. This is done by tracking each route in the route
list individually and ensuring the key-value pairs are maintained within
their respective [Route] section. This both maintains backwards
compatibility with previous behavior and allows the specification of
routes with no destination IP, causing the destination to be added with
a device target.

1 files changed, 45 insertions, 6 deletions

diff --git a/cloudinit/net/networkd.py b/cloudinit/net/networkd.py
index 3591513f..4fd8a9b8 100644
--- a/cloudinit/net/networkd.py
+++ b/cloudinit/net/networkd.py
@@ -28,7 +28,7 @@ class CfgParser:
                 "DHCPv4": [],
                 "DHCPv6": [],
                 "Address": [],
-                "Route": [],
+                "Route": {},
             }
         )
 
@@ -40,6 +40,22 @@ class CfgParser:
                 self.conf_dict[k] = list(dict.fromkeys(self.conf_dict[k]))
                 self.conf_dict[k].sort()
 
+    def update_route_section(self, sec, rid, key, val):
+        """
+        For each route section we use rid as a key, this allows us to isolate
+        this route from others on subsequent calls.
+        """
+        for k in self.conf_dict.keys():
+            if k == sec:
+                if rid not in self.conf_dict[k]:
+                    self.conf_dict[k][rid] = []
+                self.conf_dict[k][rid].append(key + "=" + str(val))
+                # remove duplicates from list
+                self.conf_dict[k][rid] = list(
+                    dict.fromkeys(self.conf_dict[k][rid])
+                )
+                self.conf_dict[k][rid].sort()
+
     def get_final_conf(self):
         contents = ""
         for k, v in sorted(self.conf_dict.items()):
@@ -50,6 +66,12 @@ class CfgParser:
                     contents += "[" + k + "]\n"
                     contents += e + "\n"
                     contents += "\n"
+            elif k == "Route":
+                for n in sorted(v):
+                    contents += "[" + k + "]\n"
+                    for e in sorted(v[n]):
+                        contents += e + "\n"
+                        contents += "\n"
             else:
                 contents += "[" + k + "]\n"
                 for e in sorted(v):
@@ -112,7 +134,11 @@ class Renderer(renderer.Renderer):
         if "mtu" in iface and iface["mtu"]:
             cfg.update_section(sec, "MTUBytes", iface["mtu"])
 
-    def parse_routes(self, conf, cfg: CfgParser):
+    def parse_routes(self, rid, conf, cfg: CfgParser):
+        """
+        Parse a route and use rid as a key in order to isolate the route from
+        others in the route dict.
+        """
         sec = "Route"
         route_cfg_map = {
             "gateway": "Gateway",
@@ -130,11 +156,12 @@ class Renderer(renderer.Renderer):
                 continue
             if k == "network":
                 v += prefix
-            cfg.update_section(sec, route_cfg_map[k], v)
+            cfg.update_route_section(sec, rid, route_cfg_map[k], v)
 
     def parse_subnets(self, iface, cfg: CfgParser):
         dhcp = "no"
         sec = "Network"
+        rid = 0
         for e in iface.get("subnets", []):
             t = e["type"]
             if t == "dhcp4" or t == "dhcp":
@@ -149,7 +176,10 @@ class Renderer(renderer.Renderer):
                     dhcp = "yes"
             if "routes" in e and e["routes"]:
                 for i in e["routes"]:
-                    self.parse_routes(i, cfg)
+                    # Use "r" as a dict key prefix for this route to isolate
+                    # it from other sources of routes
+                    self.parse_routes(f"r{rid}", i, cfg)
+                    rid = rid + 1
             if "address" in e:
                 subnet_cfg_map = {
                     "address": "Address",
@@ -163,7 +193,12 @@ class Renderer(renderer.Renderer):
                             v += "/" + str(e["prefix"])
                         cfg.update_section("Address", subnet_cfg_map[k], v)
                     elif k == "gateway":
-                        cfg.update_section("Route", subnet_cfg_map[k], v)
+                        # Use "a" as a dict key prefix for this route to
+                        # isolate it from other sources of routes
+                        cfg.update_route_section(
+                            "Route", f"a{rid}", subnet_cfg_map[k], v
+                        )
+                        rid = rid + 1
                     elif k == "dns_nameservers" or k == "dns_search":
                         cfg.update_section(sec, subnet_cfg_map[k], " ".join(v))
 
@@ -280,8 +315,12 @@ class Renderer(renderer.Renderer):
             dhcp = self.parse_subnets(iface, cfg)
             self.parse_dns(iface, cfg, ns)
 
+            rid = 0
             for route in ns.iter_routes():
-                self.parse_routes(route, cfg)
+                # Use "c" as a dict key prefix for this route to isolate it
+                # from other sources of routes
+                self.parse_routes(f"c{rid}", route, cfg)
+                rid = rid + 1
 
             if ns.version == 2:
                 name: Optional[str] = iface["name"]