patroni.dcs.etcd module¶

class patroni.dcs.etcd.AbstractEtcd(config: Dict[str, Any], client_cls: Type[patroni.dcs.etcd.AbstractEtcdClientWithFailover], retry_errors_cls: Union[Type[Exception], Tuple[Type[Exception], ...]])¶

Bases: patroni.dcs.AbstractDCS

get_etcd_client(config: Dict[str, Any], client_cls: Type[patroni.dcs.etcd.AbstractEtcdClientWithFailover]) → patroni.dcs.etcd.AbstractEtcdClientWithFailover¶

handle_etcd_exceptions(func: Callable[[...], Any], *args: Any, **kwargs: Any) → Any¶

reload_config(config: Union[Config, Dict[str, Any]]) → None¶

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.

retry(method: Callable[[...], Any], *args: Any, **kwargs: Any) → Any¶

set_retry_timeout(retry_timeout: int) → None¶: Set the new value for retry_timeout.

set_socket_options(sock: socket.socket, socket_options: Optional[Collection[Tuple[int, int, int]]]) → None¶

set_ttl(ttl: int) → Optional[bool]¶: Set the new ttl value for DCS keys.

property ttl: int¶: Get current ttl value.

class patroni.dcs.etcd.AbstractEtcdClientWithFailover(config: Dict[str, Any], dns_resolver: patroni.dcs.etcd.DnsCachingResolver, cache_ttl: int = 300)¶

Bases: abc.ABC, etcd.client.Client

ERROR_CLS: Type[Exception]¶

api_execute(path: str, method: str, params: Optional[Dict[str, Any]] = None, timeout: Optional[float] = None) → Any¶: Executes the query.

static get_srv_record(host: str) → List[Tuple[str, int]]¶

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.

property machines_cache: List[str]¶

reload_config(config: Dict[str, Any]) → None¶

set_base_uri(value: str) → None¶

set_machines_cache_ttl(cache_ttl: int) → None¶

set_read_timeout(timeout: float) → None¶

class patroni.dcs.etcd.DnsCachingResolver(cache_time: float = 600.0, cache_fail_time: float = 30.0)¶

Bases: threading.Thread

remove(host: str, port: int) → None¶

resolve(host: str, port: int) → List[Tuple[socket.AddressFamily, socket.SocketKind, int, str, Union[Tuple[str, int], Tuple[str, int, int, int]]]]¶

resolve_async(host: str, port: int, attempt: int = 0) → None¶

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: patroni.dcs.etcd.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 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: etcd.EtcdResult) → patroni.dcs.Member¶

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.

set_ttl(ttl: int) → Optional[bool]¶: Set the new ttl value for DCS keys.

take_leader(*args: Any, **kwargs: Any) → Any¶

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¶

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: patroni.dcs.etcd.DnsCachingResolver, cache_ttl: int = 300)¶

Bases: patroni.dcs.etcd.AbstractEtcdClientWithFailover

ERROR_CLS¶: alias of patroni.dcs.etcd.EtcdError

exception patroni.dcs.etcd.EtcdError(value: Any)¶: Bases: patroni.exceptions.DCSError

exception patroni.dcs.etcd.EtcdRaftInternal(message=None, payload=None)¶

Bases: etcd.EtcdException

Raft Internal Error

patroni.dcs.etcd.catch_etcd_errors(func: Callable[[...], Any]) → Any¶