traefik: Only trust network for docker < 20.10

Docker complains about the network being already marked as trusted otherwise.
Also an upgrade to docker 20.10 requires manual recreation of the networks and a removal of the docker-proxy network via `firewall-cmd --zone=trusted --remove-interface=docker-proxy`.

roles/traefik/README.md

@@ -17,6 +17,10 @@ Role Variables
 
 **Note: Lines that are commented out via `#` are usually still valid/used variables, but they are not defined by default, so they might enable a feature, when uncommenting/defining them!**  
 
+### Global variables, that are used:
+
+- `docker_package`: Defined by the docker role, this is the package name of docker within your package manager.
+
 Dependencies
 ------------
 

roles/traefik/tasks/main.yml

@@ -81,6 +81,11 @@
     - traefik_ipv6 is defined
     - traefik_ipv6.enabled
 
+- name: Gather the package facts
+  package_facts:
+    manager: auto
+
+# This step is only needed in docker < 20.10, as docker does this by default now
 - name: Trust our proxy network
   ansible.posix.firewalld:
     zone: trusted
@@ -91,6 +96,9 @@
   become: true
   tags:
     - firewall
+  when:
+    - docker_package in ansible_facts.packages
+    - ansible_facts.packages[docker_package][0].version is version('20.10', '<')
 
 - name: Deploy dynamic_conf.yml
   template: