def match(self):
        """ Makes a union of all the pods matching any of the policy criteria.
        """
        mapping = {
            "namespace": self.match_namespace,
            "deployment": self.match_deployment,
            "labels": self.match_labels,
        }
        selected = set()
        criteria = self.schema.get("matches", [])
        self.logger.debug("Criteria %r ",criteria)
        for criterion in criteria:
            for action_name, action_method in mapping.items():
                if action_name in criterion:
                    self.logger.info("Matching %r %r", action_name, criterion)
                    params = criterion.get(action_name)
                    for pod in action_method(params):
                        self.logger.debug("Matching %r", pod)
                        selected.add(pod)
        if len(selected) == 0:
            self.metric_collector.add_matched_to_empty_set_metric(POD_SOURCE)
        return list(selected)
 Makes a union of all the pods matching any of the policy criteria.
        
powerfulseal/policy/action_pods.py