create router step fails on second run

Summary

If one executes a playbook with network action of this role and wants to create ports, floating IPs, networks and routers and connect these pieces together, the playbook will fail on a second run.

Important note: use ansible 2.7.0

Steps to reproduce

Run this playbook twice:

- hosts: localhost
  gather_facts: no
  vars:
    openstack_cloud: "task-ceph-test"

    openstack_project_ports:
      - name: "test-port"
        network: "test-net"
        addresses:
          - subnetwork_name: "test-subnet"
        security_groups:
          - "default"

    openstack_project_networks:
      - name: "test-net"
        subnet_name: "test-subnet"
        subnet_cidr: "192.168.1.0/24"

    openstack_project_routers:
      - name: "test-router"
        network: "ext-net-task"
        interfaces:
          - "test-subnet"

    openstack_project_floating_ips:
      - name: "test-floating-ip"
        network: "ext-net-task"
        port: "test-port"
  tasks:
    - include_role: { name: "openstack", tasks_from: "network" }

Expected behavior

First run creates all pieces, second run changes nothing.

Actual behavior

First run creates all pieces, second run fails.

Relevant logs and/or screenshots

 ___________________________________
< TASK [openstack : create routers] >
 -----------------------------------
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

failed: [localhost -> localhost] (item=test-router) => {"_openstack_router": {"interfaces": ["test-subnet"], "name": "test-router", "network": "ext-net-task"}, "changed": false, "msg": "Error detaching interface from router d3b6d67d-edfa-4ef5-bb6c-70d34177bcf8"}

Possible fixes

After some testing the problem is connected to this issue and the resolution is to add enable_snat: yes parameter when creating router using os_router module.