patroni.dcs.etcd3 module

Bases: AbstractEtcd

__init__ ( config : Dict [ str , Any ] , mpp : AbstractMPP ) → None View on GitHub

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>

property _client : PatroniEtcd3Client View on GitHub

return correct type of etcd client

_cluster_from_nodes ( nodes : Dict [ str , Any ] ) → Cluster View on GitHub

_delete_leader ( * args : Any , ** kwargs : Any ) → Any View 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.

_do_attempt_to_acquire_leader ( retry : Retry ) → bool View on GitHub

_do_refresh_lease ( force : bool = False , retry : Retry | None = None ) → bool View on GitHub

_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.

_postgresql_cluster_loader ( path : str ) → Cluster View 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 ( ** kwargs : Any ) View 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 ( * args : Any , ** kwargs : Any ) → Any View 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 ( * args : Any , ** kwargs : Any ) → Any View 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 ( * args : Any , ** kwargs : Any ) → Any View 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 ( ** kwargs : Any ) View 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 ( * args : Any , ** kwargs : Any ) → Any View on GitHub

Removes the initialize key for a cluster.

Returns :

True if successfully committed to DCS.

property cluster_prefix : str View on GitHub

Construct the cluster prefix for the cluster.

Returns :

path in the DCS under which we store information about this Patroni cluster.

create_lease ( ) → None View on GitHub

delete_cluster ( * args : Any , ** kwargs : Any ) → Any View on GitHub

Delete cluster from DCS.

Returns :

True if successfully committed to DCS.

delete_sync_state ( * args : Any , ** kwargs : Any ) → Any View on GitHub

Delete the synchronous state from DCS.

Parameters :

version – for conditional deletion of the key/object.

Returns :

True if delete successful.

initialize ( * args : Any , ** kwargs : Any ) → Any View 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 ( node : Dict [ str , str ] ) → Member View on GitHub

refresh_lease ( ) → bool View on GitHub

set_config_value ( * args : Any , ** kwargs : Any ) → Any View 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 ( * args : Any , ** kwargs : Any ) → Any View 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 ( * args : Any , ** kwargs : Any ) → Any View on GitHub

Set value for history in DCS.

Parameters :

value – new value of history key/object.

Returns :

True if successfully committed to DCS.

set_socket_options ( sock : socket , socket_options : Collection [ Tuple [ int , int , int ] ] | None ) → None View on GitHub

set_sync_state_value ( * args : Any , ** kwargs : Any ) → Any View 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 | None View on GitHub

Set the new ttl value for DCS keys.

take_leader ( * args : Any , ** kwargs : Any ) → Any View 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 ( * args : Any , ** kwargs : Any ) → Any View 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.

watch ( leader_version : str | None , timeout : float ) → bool View 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.

Bases: AbstractEtcdClientWithFailover

ERROR_CLS View on GitHub

alias of Etcd3Error

__init__ ( config : Dict [ str , Any ] , dns_resolver : DnsCachingResolver , cache_ttl : int = 300 ) → None View on GitHub

_abc_impl = <_abc._abc_data object>

_ensure_version_prefix ( base_uri : str , ** kwargs : Any ) → None View on GitHub

_get_headers ( ) → Dict [ str , str ] View on GitHub

_get_members ( base_uri : str , ** kwargs : Any ) → List [ str ] View on GitHub

returns: list of clientURLs

_handle_server_response ( response : HTTPResponse ) → Dict [ str , Any ] View on GitHub

Handles the server response

_prepare_get_members ( etcd_nodes : int ) → Dict [ str , Any ] View on GitHub

returns: request parameters

_prepare_request ( kwargs : Dict [ str , Any ] , params : Dict [ str , Any ] | None = None , method : str | None = None ) → Callable [ [ ... ] , HTTPResponse ] View on GitHub

returns: request_executor

authenticate ( * , retry : Retry | None = None ) → bool View on GitHub

call_rpc ( method : str , fields : Dict [ str , Any ] , retry : Retry | None = None ) → Dict [ str , Any ] View on GitHub

deleteprefix ( key : str , * , retry : Retry | None = None ) → Dict [ str , Any ] View on GitHub

deleterange ( * args : Any , ** kwargs : Any ) → Any View on GitHub

handle_auth_errors ( func : Callable [ [ ... ] , Any ] , * args : Any , retry : Retry | None = None , ** kwargs : Any ) → Any View on GitHub

lease_grant ( * args : Any , ** kwargs : Any ) → Any View on GitHub

lease_keepalive ( ID : str , * , retry : Retry | None = None ) → str | None View on GitHub

prefix ( key : str , serializable : bool = True , * , retry : Retry | None = None ) → Dict [ str , Any ] View on GitHub

put ( * args : Any , ** kwargs : Any ) → Any View on GitHub

range ( * args : Any , ** kwargs : Any ) → Any View on GitHub

txn ( * args : Any , ** kwargs : Any ) → Any View on GitHub

watchprefix ( key : str , start_revision : str | None = None , filters : List [ Dict [ str , Any ] ] | None = None , read_timeout : float | None = None ) → HTTPResponse View on GitHub

watchrange ( key : str , range_end : bytes | str | None = None , start_revision : str | None = None , filters : List [ Dict [ str , Any ] ] | None = None , read_timeout : float | None = None ) → HTTPResponse View on GitHub

returns: response object

Bases: IntEnum

An enumeration.

Aborted = 10

AlreadyExists = 6

Canceled = 1

DataLoss = 15

DeadlineExceeded = 4

FailedPrecondition = 9

Internal = 13

InvalidArgument = 3

NotFound = 5

OK = 0

OutOfRange = 11

PermissionDenied = 7

ResourceExhausted = 8

Unauthenticated = 16

Unavailable = 14

Unimplemented = 12

Unknown = 2

Bases: Thread

__init__ ( dcs : Etcd3 , client : PatroniEtcd3Client ) → None View on GitHub

This constructor should always be called with keyword arguments. Arguments are:

group should be None; reserved for future extension when a ThreadGroup class is implemented.

target is the callable object to be invoked by the run() method. Defaults to None, meaning nothing is called.

name is the thread name. By default, a unique name is constructed of the form "Thread-N" where N is a small decimal number.

args is the argument tuple for the target invocation. Defaults to ().

kwargs is a dictionary of keyword arguments for the target invocation. Defaults to {}.

If a subclass overrides the constructor, it must make sure to invoke the base class constructor (Thread.__init__()) before doing anything else to the thread.

_build_cache ( ) → None View on GitHub

_do_watch ( revision : str ) → None View on GitHub

static _finish_response ( response : HTTPResponse ) → None View on GitHub

_process_event ( event : Dict [ str , Any ] ) → None View on GitHub

_process_message ( message : Dict [ str , Any ] ) → None View on GitHub

copy ( ) → List [ Dict [ str , Any ] ] View on GitHub

delete ( name : str , mod_revision : str ) → Tuple [ bool , Dict [ str , Any ] | None ] View on GitHub

get ( name : str ) → Dict [ str , Any ] | None View on GitHub

is_ready ( ) → bool View on GitHub

Must be called only when holding the lock on condition

kill_stream ( ) → None View on GitHub

run ( ) → None View on GitHub

Method representing the thread’s activity.

You may override this method in a subclass. The standard run() method invokes the callable object passed to the object’s constructor as the target argument, if any, with sequential and keyword arguments taken from the args and kwargs arguments, respectively.

set ( value : Dict [ str , Any ] , overwrite : bool = False ) → Tuple [ bool , Dict [ str , Any ] | None ] View on GitHub

Bases: Etcd3Client

__init__ ( * args : Any , ** kwargs : Any ) → None View on GitHub

_abc_impl = <_abc._abc_data object>

_restart_watcher ( ) → None View on GitHub

_wait_cache ( timeout : float ) → None View on GitHub

call_rpc ( method : str , fields : Dict [ str , Any ] , retry : Retry | None = None ) → Dict [ str , Any ] View on GitHub

configure ( etcd3 : Etcd3 ) → None View on GitHub

get_cluster ( path : str ) → List [ Dict [ str , Any ] ] View on GitHub

set_base_uri ( value : str ) → None View on GitHub

start_watcher ( ) → None View on GitHub

txn ( compare : Dict [ str , Any ] , success : Dict [ str , Any ] , failure : Dict [ str , Any ] | None = None , * , retry : Retry | None = None ) → Dict [ str , Any ] View on GitHub