derive a list of dicts from ansible groups and hostvars

playbook.yaml.jinja2

vars:
  zookeeper_nodes: "\
    {% set _zookeeper_servers = [] %}\
    {% for host in groups.zookeeper %}\
      {% set _zookeeper_client_port_address = hostvars[host]['zookeeper_client_port_address'] | default('0.0.0.0', true) %}\
      {% set _zookeeper_client_port = hostvars[host]['zookeeper_client_port'] | default(2181, true) %}\
      {% if _zookeeper_servers.append(dict(['host', 'port'] | zip([_zookeeper_client_port_address, _zookeeper_client_port]))) %}{% endif %}\
    {% endfor %}\
    {{ _zookeeper_servers }}"    

#  debug:
#
#  "zookeeper_nodes": [
#      {
#          "host": "192.168.1.27",
#          "port": 2181
#      },
#      {
#          "host": "192.168.1.115",
#          "port": 2181
#      },
#      {
#          "host": "192.168.1.13",
#          "port": 2181
#      }
#  ]