playbook: Use Ansible fact for default IPv4

Combining when and register made it impossible to have "portable" way to
find default (public) IPv4 with shell script. This is expected behaviour
of ansible, see https://github.com/ansible/ansible/issues/12779

As Ansbile provides information about a host, use it
(ansible_default_ipv4.address) to fetch this kind of address.

playbook/roles/standalone-shared/tasks/main.yml

@@ -2,18 +2,8 @@
   - name: fetch shared vars
     include_vars: erp5-common.yml
 
-  - name: Fetch public IPv4 (Debian)
-    shell: ifconfig `route -n | grep '^0\.0\.0\.0' | head -n 1 | awk '{print $NF}'` | { IFS=' :';read r;read r r a r;echo $a; }
-    register: public_ipv4
-    when: ansible_distribution == "Ubuntu" or ansible_distribution == "Debian"
-
-  - name: Fetch public IPv4 (CentOS)
-    shell: ifconfig `route -n | grep '^0\.0\.0\.0' | head -n 1 | awk '{print $NF}'` | { IFS=' :';read r;read r a r r;echo $a; }
-    register: public_ipv4
-    when: ansible_distribution == "CentOS"
-
   - name: Store public IPv4 for other scripts
-    shell: echo "{{ public_ipv4.stdout }}" > /tmp/playbook-{{ playbook_name }}-public-ipv4
+    shell: echo "{{ ansible_default_ipv4.address }}" > /tmp/playbook-{{ playbook_name }}-public-ipv4
 
   - name: create instance request script
     template: src={{ request_instance_template }} dest=/tmp/playbook-request-{{ playbook_name }} mode=700

playbook/roles/standalone-shared/templates/request-erp5-frontend.j2

 computer_id = 'local_computer'
 frontend_software_release_url = '{{ frontend_software_release_url }}'
 supply(frontend_software_release_url, computer_id)
-public_ipv4 = '{{ public_ipv4.stdout }}'
 # frontend master partition
 request(software_release=frontend_software_release_url, partition_reference='{{ frontend_master_reference }}')
 
@@ -20,7 +19,7 @@ if backend_url is not None:
     partition_parameter_kw={
         'url': backend_url,
         'type': 'zope',
-        'custom_domain': public_ipv4,
+        'custom_domain': '{{ ansible_default_ipv4.address }}',
         'server-alias': '*',
         'https-only': 'true'
     }

playbook/roles/standalone-shared/templates/setup-firewall.j2

@@ -16,8 +16,8 @@ if [ ! -z "$frontend_ipv4" ] ; then
   iptables -t nat -vnL OUTPUT | grep dpt:443 | grep -q "${local_access_comment}" && iptables -t nat -D OUTPUT `iptables -t nat -vnL OUTPUT --line-numbers | grep dpt:443 | grep "${local_access_comment}" | cut -d ' ' -f 1`
   iptables -t nat -vnL PREROUTING | grep dpt:80 | grep -q "${remote_access_comment}" && iptables -t nat -D PREROUTING `iptables -t nat -vnL PREROUTING --line-numbers | grep dpt:80 | grep "${remote_access_comment}" | cut -d ' ' -f 1`
   iptables -t nat -vnL OUTPUT | grep dpt:80 | grep -q "${local_access_comment}" && iptables -t nat -D OUTPUT `iptables -t nat -vnL OUTPUT --line-numbers | grep dpt:80 | grep "${local_access_comment}" | cut -d ' ' -f 1`
-  iptables -t nat -A OUTPUT -p tcp -d {{ public_ipv4.stdout }} --dport 443 -j DNAT --to $frontend_ipv4:4443 -m comment --comment "${local_access_comment}"
-  iptables -t nat -A PREROUTING -p tcp -d {{ public_ipv4.stdout }} --dport 443 -j DNAT --to-destination $frontend_ipv4:4443 -m comment --comment "${remote_access_comment}"
-  iptables -t nat -A OUTPUT -p tcp -d {{ public_ipv4.stdout }} --dport 80 -j DNAT --to $frontend_ipv4:8080 -m comment --comment "${local_access_comment}"
-  iptables -t nat -A PREROUTING -p tcp -d {{ public_ipv4.stdout }} --dport 80 -j DNAT --to-destination $frontend_ipv4:8080 -m comment --comment "${remote_access_comment}"
+  iptables -t nat -A OUTPUT -p tcp -d {{ ansible_default_ipv4.address }} --dport 443 -j DNAT --to $frontend_ipv4:4443 -m comment --comment "${local_access_comment}"
+  iptables -t nat -A PREROUTING -p tcp -d {{ ansible_default_ipv4.address }} --dport 443 -j DNAT --to-destination $frontend_ipv4:4443 -m comment --comment "${remote_access_comment}"
+  iptables -t nat -A OUTPUT -p tcp -d {{ ansible_default_ipv4.address }} --dport 80 -j DNAT --to $frontend_ipv4:8080 -m comment --comment "${local_access_comment}"
+  iptables -t nat -A PREROUTING -p tcp -d {{ ansible_default_ipv4.address }} --dport 80 -j DNAT --to-destination $frontend_ipv4:8080 -m comment --comment "${remote_access_comment}"
 fi