Allow to specify a source address for metallb peerings, and target only some...

Allow to specify a source address for metallb peerings, and target only some nodes using node selectors (#8534)

roles/kubernetes-apps/metallb/templates/metallb-config.yml.j2

@@ -12,6 +12,13 @@ data:
     - peer-address: {{ peer.peer_address }}
       peer-asn: {{ peer.peer_asn }}
       my-asn: {{ peer.my_asn }}
+{% if peer.source_address is defined %}
+      source-address: {{ peer.source_address }}
+{% endif %}
+{% if peer.node_selectors is defined %}
+      node-selectors:
+        {{ peer.node_selectors | to_yaml(indent=2, width=1337) | indent(8) }}
+{% endif %}
 {% endfor %}
 {% endif %}
     address-pools: