Allow to omit the RAFT port (zalando#1759)

If no ports are specified for self_addr, bind_addr and/or partner_addrs, then
Patroni will self-assign the startup API port + 10000 as RAFT port.

docs/SETTINGS.rst

@@ -241,6 +241,9 @@ Raft
 
  A: Yes, on the third node you can run ``patroni_raft_controller`` (without Patroni and PostgreSQL). In such a setup, one can temporarily lose one node without affecting the primary.
 
+ - Q: Do I need to specify a port?
+
+ A: No, if you omit the port, Patroni will prepend the startup API port with 1 (i.e. add 10000 to it).
 
 .. _postgresql_settings:
 

patroni/dcs/__init__.py

@@ -93,7 +93,7 @@ def get_dcs(config):
  if key.lower() == name and inspect.isclass(item) and issubclass(item, AbstractDCS):
  # propagate some parameters
  config[name].update({p: config[p] for p in ('namespace', 'name', 'scope', 'loop_wait',
- 'patronictl', 'ttl', 'retry_timeout') if p in config})
+ 'patronictl', 'ttl', 'retry_timeout', 'restapi') if p in config})
  return item(config[name])
  except ImportError:
  logger.debug('Failed to import %s', module_name)

patroni/dcs/raft.py

@@ -265,6 +265,9 @@ def __init__(self, config):
  super(Raft, self).__init__(config)
  self._ttl = int(config.get('ttl') or 30)
 
+ # Set a default port if no ports were specified in config
+ self._default_port(config)
+
  ready_event = threading.Event()
  self._sync_obj = KVStoreTTL(ready_event.set, self._on_set, self._on_delete, commandsWaitLeader=False, **config)
  self._sync_obj.startAutoTick()
@@ -277,6 +280,19 @@ def __init__(self, config):
  logger.info('waiting on raft')
  self.set_retry_timeout(int(config.get('retry_timeout') or 10))
 
+ def _default_port(self, config):
+ # Prepend '1' to the API port, i.e. use '18008' if the API port is '8008'
+ port = '1' + config['restapi']['listen'].rsplit(':', 1)[1]
+ n = 0
+ for addr in config['partner_addrs']:
+ if ":" not in addr:
+ config['partner_addrs'][n] = addr + ':' + port
+ n += 1
+ if ":" not in config['self_addr']:
+ config['self_addr'] = config['self_addr'] + ':' + port
+ if ":" not in config['bind_addr']:
+ config['bind_addr'] = config['bind_addr'] + ':' + port
+
  def _on_set(self, key, value):
  leader = (self._sync_obj.get(self.leader_path) or {}).get('value')
  if key == value['created'] == value['updated'] and \