patroni.dcs.raft module

class patroni.dcs.raft.DynMemberSyncObj(selfAddress: str | None, partnerAddrs: Collection[str], conf: SyncObjConf, retry_timeout: int = 10)View on GitHub 

Bases: SyncObj

__init__(selfAddress: str | None, partnerAddrs: Collection[str], conf: SyncObjConf, retry_timeout: int = 10) → NoneView on GitHub 

Main SyncObj class, you should inherit your own class from it.

Parameters:

selfNode (Node or str) – object representing the self-node or address of the current node server ‘host:port’
otherNodes (iterable of Node or iterable of str) – objects representing the other nodes or addresses of partner nodes [‘host1:port1’, ‘host2:port2’, …]
conf (SyncObjConf) – configuration object
consumers (list of SyncObjConsumer inherited objects) – objects to be replicated
nodeClass (class) – class used for representation of nodes
transport (Transport or None) – transport object; if None, transportClass is used to initialise such an object
transportClass (class) – the Transport subclass to be used for transferring messages to and from other nodes

_onTick(timeToWait: float = 0.0)View on GitHub 

getMembers(args: Any, callback: Callable[[Any, Any], Any]) → NoneView on GitHub 

class patroni.dcs.raft.KVStoreTTL(on_ready: Callable[[...], Any] | None, on_set: Callable[[str, Dict[str, Any]], None] | None, on_delete: Callable[[str], None] | None, **config: Any)View on GitHub 

Bases: DynMemberSyncObj

__check_requirements(**kwargs: Any) → bool

__expire_keys() → None

__init__(on_ready: Callable[[...], Any] | None, on_set: Callable[[str, Dict[str, Any]], None] | None, on_delete: Callable[[str], None] | None, **config: Any) → NoneView on GitHub 

Main SyncObj class, you should inherit your own class from it.

Parameters:

selfNode (Node or str) – object representing the self-node or address of the current node server ‘host:port’
otherNodes (iterable of Node or iterable of str) – objects representing the other nodes or addresses of partner nodes [‘host1:port1’, ‘host2:port2’, …]
conf (SyncObjConf) – configuration object
consumers (list of SyncObjConsumer inherited objects) – objects to be replicated
nodeClass (class) – class used for representation of nodes
transport (Transport or None) – transport object; if None, transportClass is used to initialise such an object
transportClass (class) – the Transport subclass to be used for transferring messages to and from other nodes

__pop(key: str) → None

__values_match(new: Dict[str, Any]) → bool

_autoTickThread() → NoneView on GitHub 

_delete(key: str, recursive: bool = False, **kwargs: Any) → boolView on GitHub 

_delete_v0(key: str, recursive: bool = False, **kwargs: Any) → boolView on GitHub 

_expire(key: str, value: Dict[str, Any], callback: Callable[[...], Any] | None = None) → NoneView on GitHub 

_expire_v0(key: str, value: Dict[str, Any], callback: Callable[[...], Any] | None = None) → NoneView on GitHub 

_onTick(timeToWait: float = 0.0) → NoneView on GitHub 

_set(key: str, value: Dict[str, Any], **kwargs: Any) → bool | Dict[str, Any]View on GitHub 

_set_v0(key: str, value: Dict[str, Any], **kwargs: Any) → bool | Dict[str, Any]View on GitHub 

delete(key: str, recursive: bool = False, **kwargs: Any) → boolView on GitHub 

destroy() → NoneView on GitHub : Correctly destroy SyncObj. Stop autoTickThread, close connections, etc.

get(key: str, recursive: bool = False) → None | Dict[str, Any] | Dict[str, Dict[str, Any]]View on GitHub 

retry(func: Callable[[...], Any], *args: Any, **kwargs: Any) → AnyView on GitHub 

set(key: str, value: str, ttl: int | None = None, handle_raft_error: bool = True, **kwargs: Any) → bool | Dict[str, Any]View on GitHub 

set_retry_timeout(retry_timeout: int) → NoneView on GitHub 

startAutoTick() → NoneView on GitHub 

class patroni.dcs.raft.Raft(config: Dict[str, Any], mpp: AbstractMPP)View on GitHub 

Bases: AbstractDCS

__init__(config: Dict[str, Any], mpp: AbstractMPP) → NoneView on GitHub 

Prepare DCS paths, MPP object, initial values for state information and processing dependencies.

Variables:: config – dict, reference to config section of selected DCS. i.e.: zookeeper for zookeeper, etcd for etcd, etc…

_abc_impl = <_abc._abc_data object>

_cluster_from_nodes(nodes: Dict[str, Any]) → ClusterView on GitHub 

_delete_leader(leader: Leader) → boolView on GitHub 

Remove leader key from DCS.

This method should remove leader key if current instance is the leader.

Parameters:: leader – Leader object with information about the leader.
Returns:: True if successfully committed to DCS.

_load_cluster(path: str, loader: Callable[[str], Cluster | Dict[int, Cluster]]) → Cluster | Dict[int, Cluster]View on GitHub 

Main abstract method that implements the loading of Cluster instance.

Note

Internally this method should call the loader method that will build Cluster object which represents current state and topology of the cluster in DCS. This method supposed to be called only by the get_cluster() method.

Parameters:

path – the path in DCS where to load Cluster(s) from.
loader – one of _postgresql_cluster_loader() or _mpp_cluster_loader().

Raise:

DCSError in case of communication problems with DCS. If the current node was running as a primary and exception raised, instance would be demoted.

_mpp_cluster_loader(path: str) → Dict[int, Cluster]View on GitHub 

Load and build all PostgreSQL clusters from a single MPP cluster.

Parameters:: path – the path in DCS where to load Cluster(s) from.
Returns:: all MPP groups as dict, with group IDs as keys and Cluster objects as values.

_on_delete(key: str) → NoneView on GitHub 

_on_set(key: str, value: Dict[str, Any]) → NoneView on GitHub 

_postgresql_cluster_loader(path: str) → ClusterView on GitHub 

Load and build the Cluster object from DCS, which represents a single PostgreSQL cluster.

Parameters:: path – the path in DCS where to load Cluster from.
Returns:: Cluster instance.

_update_leader(leader: Leader) → boolView on GitHub 

Update leader key (or session) ttl.

Note

You have to use CAS (Compare And Swap) operation in order to update leader key, for example for etcd prevValue parameter must be used.

If update fails due to DCS not being accessible or because it is not able to process requests (hopefully temporary), the DCSError exception should be raised.

Parameters:: leader – a reference to a current leader object.
Returns:: True if leader key (or session) has been updated successfully.

_write_failsafe(value: str) → boolView on GitHub 

Write current cluster topology to DCS that will be used by failsafe mechanism (if enabled).

Parameters:: value – failsafe topology serialized in JSON format.
Returns:: True if successfully committed to DCS.

_write_leader_optime(last_lsn: str) → boolView on GitHub 

Write current WAL LSN into /optime/leader key in DCS.

Parameters:: last_lsn – absolute WAL LSN in bytes.
Returns:: True if successfully committed to DCS.

_write_status(value: str) → boolView on GitHub 

Write current WAL LSN and confirmed_flush_lsn of permanent slots into the /status key in DCS.

Parameters:: value – status serialized in JSON format.
Returns:: True if successfully committed to DCS.

attempt_to_acquire_leader() → boolView on GitHub 

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() → boolView on GitHub 

Removes the initialize key for a cluster.

Returns:: True if successfully committed to DCS.

delete_cluster() → boolView on GitHub 

Delete cluster from DCS.

Returns:: True if successfully committed to DCS.

delete_sync_state(version: int | None = None) → boolView on GitHub 

Delete the synchronous state from DCS.

Parameters:: version – for conditional deletion of the key/object.
Returns:: True if delete successful.

initialize(create_new: bool = True, sysid: str = '') → boolView on GitHub 

Race for cluster initialization.

This method should atomically create initialize key and return True, otherwise it should return False.

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.

static member(key: str, value: Dict[str, Any]) → MemberView on GitHub 

reload_config(config: Config | Dict[str, Any]) → NoneView on GitHub 

Load and set relevant values from configuration.

Sets loop_wait, ttl and retry_timeout properties.

Parameters:: config – Loaded configuration information object or dictionary of key value pairs.

set_config_value(value: str, version: int | None = None) → boolView on GitHub 

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: int | None = None) → boolView on GitHub 

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) → boolView on GitHub 

Set value for history in DCS.

Parameters:: value – new value of history key/object.
Returns:: True if successfully committed to DCS.

set_retry_timeout(retry_timeout: int) → NoneView on GitHub : Set the new value for retry_timeout.

set_sync_state_value(value: str, version: int | None = None) → int | boolView on GitHub 

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) → bool | NoneView on GitHub : Set the new ttl value for DCS keys.

take_leader() → boolView on GitHub 

Establish a new leader in DCS.

Note

This method should create leader key with value of _name and ttl of ttl.

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]) → boolView on GitHub 

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: int: Get current ttl value.

watch(leader_version: int | None, timeout: float) → boolView on GitHub 

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.raft.RaftError(value: Any)View on GitHub : Bases: DCSError

class patroni.dcs.raft.SyncObjUtility(otherNodes: Collection[str | TCPNode], conf: SyncObjConf, retry_timeout: int = 10)View on GitHub 

Bases: object

__init__(otherNodes: Collection[str | TCPNode], conf: SyncObjConf, retry_timeout: int = 10) → NoneView on GitHub 

executeCommand(command: List[Any]) → AnyView on GitHub 

getMembers() → List[str] | NoneView on GitHub 

class patroni.dcs.raft._TCPTransport(syncObj: DynMemberSyncObj, selfNode: TCPNode | None, otherNodes: Collection[TCPNode])View on GitHub 

Bases: TCPTransport

__init__(syncObj: DynMemberSyncObj, selfNode: TCPNode | None, otherNodes: Collection[TCPNode]) → NoneView on GitHub 

Initialise the TCP transport. On normal (non-read-only) nodes, this will start a TCP server. On all nodes, it will initiate relevant connections to other nodes.

Parameters:

syncObj (SyncObj) – SyncObj
selfNode (TCPNode or None) – current node (None if this is a read-only node)
otherNodes (iterable of TCPNode) – partner nodes

_connectIfNecessarySingle(node: TCPNode) → boolView on GitHub 

Connect to a node if necessary.

Parameters:: node (Node) – node to connect to

patroni.dcs.raft.resolve_host(self: TCPNode) → str | NoneView on GitHub 