Consul is another key-value layer we can use instead of etcd. As with ZooKeeper, it's possible that an infrastructure department has already decided on the official software for several dedicated roles. If this is the case and Consul is the chosen key-value store within the company, it would be silly to maintain another without some overriding reason.
There may be reason to prefer one key-value layer over another, but that conversation is far beyond the scope of this book. Instead of initiating an argument on the fine points of leader election algorithms, let's convert our stack to Consul in place of etcd.
Please note that installing Consul itself is beyond the scope of this recipe. The intention here is to make changes to Patroni that make it compatible with an existing Consul installation. This can happen when an infrastructure already incorporates Consul, allowing us to leverage it as well.