patroni.dcs.raft module¶
- class patroni.dcs.raft.DynMemberSyncObj(selfAddress: Optional[str], partnerAddrs: Collection[str], conf: pysyncobj.config.SyncObjConf, retry_timeout: int = 10)¶
Bases:
pysyncobj.syncobj.SyncObj
- __init__(selfAddress: Optional[str], partnerAddrs: Collection[str], conf: pysyncobj.config.SyncObjConf, retry_timeout: int = 10) None ¶
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
- class patroni.dcs.raft.KVStoreTTL(on_ready: Optional[Callable[[...], Any]], on_set: Optional[Callable[[str, Dict[str, Any]], None]], on_delete: Optional[Callable[[str], None]], **config: Any)¶
Bases:
patroni.dcs.raft.DynMemberSyncObj
- __init__(on_ready: Optional[Callable[[...], Any]], on_set: Optional[Callable[[str, Dict[str, Any]], None]], on_delete: Optional[Callable[[str], None]], **config: Any) None ¶
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
- retry(func: Callable[[...], Any], *args: Any, **kwargs: Any) Any ¶
- class patroni.dcs.raft.Raft(config: Dict[str, Any], mpp: patroni.postgresql.mpp.AbstractMPP)¶
Bases:
patroni.dcs.AbstractDCS
- __init__(config: Dict[str, Any], mpp: patroni.postgresql.mpp.AbstractMPP) None ¶
Prepare DCS paths, MPP object, initial values for state information and processing dependencies.
- Parameters
config –
dict
, reference to config section of selected DCS. i.e.:zookeeper
for zookeeper,etcd
for etcd, etc…mpp – an object implementing
AbstractMPP
interface.
- _abc_impl = <_abc._abc_data object>¶
- _cluster_from_nodes(nodes: Dict[str, Any]) patroni.dcs.Cluster ¶
- _delete_leader(leader: patroni.dcs.Leader) bool ¶
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], Union[patroni.dcs.Cluster, Dict[int, patroni.dcs.Cluster]]]) Union[patroni.dcs.Cluster, Dict[int, patroni.dcs.Cluster]] ¶
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 theget_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, patroni.dcs.Cluster] ¶
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 andCluster
objects as values.
- _postgresql_cluster_loader(path: str) patroni.dcs.Cluster ¶
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: patroni.dcs.Leader) bool ¶
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
ifleader
key (or session) has been updated successfully.
- _write_failsafe(value: str) bool ¶
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) bool ¶
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) bool ¶
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() 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.
- 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.
- static member(key: str, value: Dict[str, Any]) 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.
- 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.
- 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.raft.RaftError(value: Any)¶
Bases:
patroni.exceptions.DCSError
- class patroni.dcs.raft.SyncObjUtility(otherNodes: Collection[Union[str, pysyncobj.node.TCPNode]], conf: pysyncobj.config.SyncObjConf, retry_timeout: int = 10)¶
Bases:
object
- __init__(otherNodes: Collection[Union[str, pysyncobj.node.TCPNode]], conf: pysyncobj.config.SyncObjConf, retry_timeout: int = 10) None ¶
- executeCommand(command: List[Any]) Any ¶
- class patroni.dcs.raft._TCPTransport(syncObj: patroni.dcs.raft.DynMemberSyncObj, selfNode: Optional[pysyncobj.node.TCPNode], otherNodes: Collection[pysyncobj.node.TCPNode])¶
Bases:
pysyncobj.transport.TCPTransport
- __init__(syncObj: patroni.dcs.raft.DynMemberSyncObj, selfNode: Optional[pysyncobj.node.TCPNode], otherNodes: Collection[pysyncobj.node.TCPNode]) None ¶
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