parse: fix renderer validation for nm-devices (LP: #2091755)

[daniloegea]

When we process a nm-device we check to see if the renderer is NetworkManager. If it's not set to NetworkManager we log a warning message and change the backend.

This verification can be only done after the netdef is processed. Move the verification so it happens after the call to process_mapping().

Fixes LP: #2091755

Reproducer:

network:
  version: 2
  nm-devices:
    NM-db5f0f67-1f4c-4d59-8ab8-3d278389cf87:
      renderer: NetworkManager
      networkmanager:
        uuid: "db5f0f67-1f4c-4d59-8ab8-3d278389cf87"
        name: "myvpnconnection"
        passthrough:
          connection.type: "vpn"

$ netplan --debug get --root-dir /tmp/fakeroot
** (process:70728): DEBUG: 15:57:33.741: starting new processing pass
** (process:70728): DEBUG: 15:57:33.741: netplan: NM-db5f0f67-1f4c-4d59-8ab8-3d278389cf87: handling NetworkManager passthrough device, settings are not fully supported.
** (process:70728): DEBUG: 15:57:33.741: nm-device: NM-db5f0f67-1f4c-4d59-8ab8-3d278389cf87: the renderer for nm-devices must be NetworkManager, it will be used instead of the defined one.
** (process:70728): DEBUG: 15:57:33.741: We have some netdefs, pass them through a final round of validation
** (process:70728): DEBUG: 15:57:33.741: Configuration is valid
network:
  version: 2
  nm-devices:
    NM-db5f0f67-1f4c-4d59-8ab8-3d278389cf87:
      renderer: NetworkManager
      networkmanager:
        uuid: "db5f0f67-1f4c-4d59-8ab8-3d278389cf87"
        name: "myvpnconnection"
        passthrough:
          connection.type: "vpn"

Note that the message the renderer for nm-devices must be NetworkManager, it will be used instead of the defined one is present even though the renderer is explicitly set to NetworkManager.

Description

Checklist

• Runs make check successfully.
• Retains code coverage (make check-coverage).
• New/changed keys in YAML format are documented.
• (Optional) Adds example YAML for new feature.
• (Optional) Closes an open bug in Launchpad.

[slyon]

lgtm