Only one route is generated from multiple files with different tables and same vlan

[Iku Iwasa]

Suppose the following 3 files exist in /etc/netplan.

# 01-netcfg.yaml
network:
  version: 2
  renderer: networkd
  ethernets:
    eth0:
      dhcp4: false
      dhcp6: false
      addresses: [172.17.17.151/20]
      routes:
        - to: default
          via: 172.17.17.1
      nameservers:
        addresses: [4.2.2.1, 4.2.2.2, 208.67.220.220]
  vlans:
    vlan100:
      id: 100
      link: eth0
      addresses: [10.0.0.1/24,10.0.0.2/24]

# 10-table1.yaml
network:
  version: 2
  vlans:
    vlan100:
      routing-policy:
        - from: 10.0.0.1
          table: 1001
      routes:
        - to: 0.0.0.0/0
          via: 10.0.0.100
          table: 1001

# 10-table2.yaml
network:
  version: 2
  vlans:
    vlan100:
      routing-policy:
        - from: 10.0.0.2
          table: 1002
      routes:
        - to: 0.0.0.0/0
          via: 10.0.0.200
          table: 1002

Then, `netplan apply` generates a route for table 1001 only.

# output of netplan apply
network:
  version: 2
  renderer: networkd
  ethernets:
    eth0:
      addresses:
      - "172.17.17.151/20"
      nameservers:
        addresses:
        - 4.2.2.1
        - 4.2.2.2
        - 208.67.220.220
      dhcp4: false
      dhcp6: false
      routes:
      - to: "default"
        via: "172.17.17.1"
  vlans:
    vlan100:
      addresses:
      - "10.0.0.1/24"
      - "10.0.0.2/24"
      routes:
      - table: 1001
        to: "0.0.0.0/0"
        via: "10.0.0.100"
      routing-policy:
      - table: 1001
        from: "10.0.0.1"
      - table: 1002
        from: "10.0.0.2"
      id: 100
      link: "eth0"

Expected `network.vlans.vlan100.routes` node is as follows.
# part of expected output
      routes:
      - table: 1001
        to: "0.0.0.0/0"
        via: "10.0.0.100"
      - table: 1002
        to: "0.0.0.0/0"
        via: "10.0.0.200"

If 10-table1.yaml and 10-table2.yaml are merged to one file like below, `network.vlans.vlan100.routes` node is generated as expected.

# 20-merged.yaml
network:
  version: 2
  vlans:
    vlan100:
      routing-policy:
        - from: 10.0.0.1
          table: 1001
        - from: 10.0.0.2
          table: 1002
      routes:
        - to: 0.0.0.0/0
          via: 10.0.0.100
          table: 1001
        - to: 0.0.0.0/0
          via: 10.0.0.200
          table: 1002

Same contents in Gist for readability.
https://gist.github.com/iquiw/373a139e4ab773574983293061d979bb

[Lukas Märdian (slyon)]

Indeed, I think something might be wrong with netplan's additive route merging logic.

[Danilo Egea Gondolfo (danilogondolfo)]

I can confirm the issue. For the example above, the generated configuration will have only one route:

$ cat systemd/network/10-netplan-vlan100.network
[Match]
Name=vlan100

[Network]
LinkLocalAddressing=ipv6
Address=10.0.0.1/24
Address=10.0.0.2/24
ConfigureWithoutCarrier=yes

[Route]
Destination=0.0.0.0/0
Gateway=10.0.0.100
Table=1001

[RoutingPolicyRule]
From=10.0.0.1
Table=1001

[RoutingPolicyRule]
From=10.0.0.2
Table=1002

I'm investigating the issue and working on a fix.

Thanks for reporting the problem.

[Danilo Egea Gondolfo (danilogondolfo)]

I've created a patch with a possible solution for this issue: https://github.com/canonical/netplan/pull/320