patroni.dcs.zookeeper module¶
-
class
patroni.dcs.zookeeper.
PatroniKazooClient
(hosts='127.0.0.1:2181', timeout=10.0, client_id=None, handler=None, default_acl=None, auth_data=None, sasl_options=None, read_only=None, randomize_hosts=True, connection_retry=None, command_retry=None, logger=None, keyfile=None, keyfile_password=None, certfile=None, ca=None, use_ssl=False, verify_certs=True, **kwargs)¶ Bases:
kazoo.client.KazooClient
-
class
patroni.dcs.zookeeper.
PatroniSequentialThreadingHandler
(connect_timeout: Union[int, float])¶ Bases:
kazoo.handlers.threading.SequentialThreadingHandler
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create_connection
(*args: Any, **kwargs: Any) → socket.socket¶ - This method is trying to establish connection with one of the zookeeper nodes.
Somehow strategy “fail earlier and retry more often” works way better comparing to the original strategy “try to connect with specified timeout”. Since we want to try connect to zookeeper more often (with the smaller connect_timeout), he have to override create_connection method in the SequentialThreadingHandler class (which is used by kazoo.Client).
- Parameters
args – always contains tuple(host, port) as the first element and could contain connect_timeout (negotiated session timeout) as the second element.
-
select
(*args: Any, **kwargs: Any) → Any¶ Python 3.XY may raise following exceptions if select/poll are called with an invalid socket: - ValueError: because fd == -1 - TypeError: Invalid file descriptor: -1 (starting from kazoo 2.9) Python 2.7 may raise the IOError instead of socket.error (starting from kazoo 2.9)
When it is appropriate we map these exceptions to socket.error.
-
-
class
patroni.dcs.zookeeper.
ZooKeeper
(config: Dict[str, Any])¶ Bases:
patroni.dcs.AbstractDCS
-
attempt_to_acquire_leader
() → bool¶ Attempt to acquire leader lock.
Note
This method should create
/leader
key with the value_name
.The key must be created atomically. In case the key already exists it should not be overwritten and
False
must be returned.If key creation fails due to DCS not being accessible or because it is not able to process requests (hopefully temporary), the
DCSError
exception should be raised.- Returns
True
if key has been created successfully.
-
cancel_initialization
() → bool¶ Removes the
initialize
key for a cluster.- Returns
True
if successfully committed to DCS.
-
delete_sync_state
(version: Optional[int] = None) → bool¶ Delete the synchronous state from DCS.
- Parameters
version – for conditional deletion of the key/object.
- Returns
True
if delete successful.
-
get_children
(key: str, watch: Optional[Callable[[kazoo.protocol.states.WatchedEvent], None]] = None) → List[str]¶
-
get_node
(key: str, watch: Optional[Callable[[kazoo.protocol.states.WatchedEvent], None]] = None) → Optional[Tuple[str, kazoo.protocol.states.ZnodeStat]]¶
-
initialize
(create_new: bool = True, sysid: str = '') → bool¶ Race for cluster initialization.
This method should atomically create
initialize
key and returnTrue
, otherwise it should returnFalse
.- Parameters
create_new –
False
if the key should already exist (in the case we are setting the system_id).sysid – PostgreSQL cluster system identifier, if specified, is written to the key.
- Returns
True
if key has been created successfully.
-
load_members
(path: str) → List[patroni.dcs.Member]¶
-
static
member
(name: str, value: str, znode: kazoo.protocol.states.ZnodeStat) → patroni.dcs.Member¶
-
reload_config
(config: Union[Config, Dict[str, Any]]) → None¶ Load and set relevant values from configuration.
Sets
loop_wait
,ttl
andretry_timeout
properties.- Parameters
config – Loaded configuration information object or dictionary of key value pairs.
-
set_config_value
(value: str, version: Optional[int] = None) → bool¶ Create or update
/config
key in DCS.- Parameters
value – new value to set in the
config
key.version – for conditional update of the key/object.
- Returns
True
if successfully committed to DCS.
-
set_failover_value
(value: str, version: Optional[int] = None) → bool¶ Create or update
/failover
key.- Parameters
value – value to set.
version – for conditional update of the key/object.
- Returns
True
if successfully committed to DCS.
-
set_history_value
(value: str) → bool¶ Set value for
history
in DCS.- Parameters
value – new value of
history
key/object.- Returns
True
if successfully committed to DCS.
-
set_sync_state_value
(value: str, version: Optional[int] = None) → Union[int, bool]¶ Set synchronous state in DCS.
- Parameters
value – the new value of
/sync
key.version – for conditional update of the key/object.
- Returns
version of the new object or
False
in case of error.
-
set_ttl
(ttl: int) → Optional[bool]¶ It is not possible to change ttl (session_timeout) in zookeeper without destroying old session and creating the new one. This method returns !True if session_timeout has been changed (restart() has been called).
-
take_leader
() → bool¶ Establish a new leader in DCS.
Note
This method should create leader key with value of
_name
andttl
ofttl
.Since it could be called only on initial cluster bootstrap it could create this key regardless, overwriting the key if necessary.
- Returns
True
if successfully committed to DCS.
-
touch_member
(data: Dict[str, Any]) → bool¶ Update member key in DCS.
Note
This method should create or update key with the name with
/members/
+_name
and the value of data in a given DCS.- Parameters
data – information about an instance (including connection strings).
- Returns
True
if successfully committed to DCS.
-
property
ttl
¶ Get current
ttl
value.
-
watch
(leader_version: Optional[int], timeout: float) → bool¶ Sleep if the current node is a leader, otherwise, watch for changes of leader key with a given timeout.
- Parameters
leader_version – version of a leader key.
timeout – timeout in seconds.
- Returns
if
True
this will reschedule the next run of the HA cycle.
-
-
exception
patroni.dcs.zookeeper.
ZooKeeperError
(value: Any)¶ Bases:
patroni.exceptions.DCSError