patroni.dcs.etcd module¶
- class patroni.dcs.etcd.AbstractEtcd(config: Dict[str, Any], client_cls: Type[AbstractEtcdClientWithFailover], retry_errors_cls: Union[Type[Exception], Tuple[Type[Exception], ...]])¶
Bases:
AbstractDCS
- get_etcd_client(config: Dict[str, Any], client_cls: Type[AbstractEtcdClientWithFailover]) AbstractEtcdClientWithFailover ¶
- class patroni.dcs.etcd.AbstractEtcdClientWithFailover(config: Dict[str, Any], dns_resolver: DnsCachingResolver, cache_ttl: int = 300)¶
Bases:
ABC
,Client
- api_execute(path: str, method: str, params: Optional[Dict[str, Any]] = None, timeout: Optional[float] = None) Any ¶
Executes the query.
- property machines: List[str]¶
Original machines method(property) of etcd.Client class raise exception when it failed to get list of etcd cluster members. This method is being called only when request failed on one of the etcd members during api_execute call. For us it’s more important to execute original request rather then get new topology of etcd cluster. So we will catch this exception and return empty list of machines. Later, during next api_execute call we will forcefully update machines_cache.
Also this method implements the same timeout-retry logic as api_execute, because the original method was retrying 2 times with the read_timeout on each node.
After the next refactoring the whole logic was moved to the _get_machines_list() method.
- class patroni.dcs.etcd.DnsCachingResolver(cache_time: float = 600.0, cache_fail_time: float = 30.0)¶
Bases:
Thread
- resolve(host: str, port: int) List[Tuple[AddressFamily, SocketKind, int, str, Union[Tuple[str, int], Tuple[str, int, int, int]]]] ¶
- run() None ¶
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.
- class patroni.dcs.etcd.Etcd(config: Dict[str, Any])¶
Bases:
AbstractEtcd
- attempt_to_acquire_leader(**kwargs: Any)¶
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 ¶
Removes the
initialize
key for a cluster.- Returns:
True
if successfully committed to DCS.
- delete_cluster(*args: Any, **kwargs: Any) Any ¶
Delete cluster from DCS.
- Returns:
True
if successfully committed to DCS.
- delete_sync_state(*args: Any, **kwargs: Any) Any ¶
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 ¶
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.
- set_config_value(*args: Any, **kwargs: Any) Any ¶
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 ¶
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 ¶
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(*args: Any, **kwargs: Any) Any ¶
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(*args: Any, **kwargs: Any) Any ¶
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(*args: Any, **kwargs: Any) Any ¶
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.
- class patroni.dcs.etcd.EtcdClient(config: Dict[str, Any], dns_resolver: DnsCachingResolver, cache_ttl: int = 300)¶
- exception patroni.dcs.etcd.EtcdRaftInternal(message=None, payload=None)¶
Bases:
EtcdException
Raft Internal Error