patroni.dcs.consul module

class patroni.dcs.consul.Consul(config: Dict[str, Any], mpp: AbstractMPP)

Bases: AbstractDCS

__init__(config: Dict[str, Any], mpp: AbstractMPP) None

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

Parameters:
  • configdict, 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]) Cluster
property _consistency: str
_delete_leader(**kwargs: Any) Any

Remove leader key from DCS.

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

Parameters:

leaderLeader object with information about the leader.

Returns:

True if successfully committed to DCS.

_do_attempt_to_acquire_leader(retry: Retry) bool
_do_refresh_session(force: bool = False) bool
Returns:

!True if it had to create new session

_load_cluster(path: str, loader: Callable[[str], Cluster | Dict[int, Cluster]]) Cluster | Dict[int, 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 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]

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

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.

static _run_and_handle_exceptions(method: Callable[[...], Any], *args: Any, **kwargs: Any) Any
_set_service_name() None
_update_leader(**kwargs: Any)

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.

_update_service(data: Dict[str, Any]) bool | None
_write_failsafe(**kwargs: Any) Any

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(**kwargs: Any) Any

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(**kwargs: Any) Any

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.

adjust_ttl() None
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(**kwargs: Any) Any

Removes the initialize key for a cluster.

Returns:

True if successfully committed to DCS.

create_session() None
delete_cluster(**kwargs: Any) Any

Delete cluster from DCS.

Returns:

True if successfully committed to DCS.

delete_sync_state(**kwargs: Any) Any

Delete the synchronous state from DCS.

Parameters:

version – for conditional deletion of the key/object.

Returns:

True if delete successful.

deregister_service(**kwargs: Any) Any
initialize(**kwargs: Any) Any

Race for cluster initialization.

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

Parameters:
  • create_newFalse 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
refresh_session() bool
register_service(**kwargs: Any) Any
reload_config(config: 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_config_value(**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(**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(**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_retry_timeout(retry_timeout: int) None

Set the new value for retry_timeout.

set_sync_state_value(**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) bool | None

Set the new ttl value for DCS keys.

take_leader() bool

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(**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.

property ttl: int

Get current ttl value.

update_service(**kwargs: Any) Any
watch(leader_version: int | None, 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.consul.ConsulClient(*args: Any, **kwargs: Any)

Bases: Consul

__init__(*args: Any, **kwargs: Any) None

Consul client with Patroni customisations.

Note

Parameters, token, cert and ca_cert are not passed to the parent class consul.base.Consul.

Original class documentation,

token is an optional ACL token. If supplied it will be used by default for all requests made with this client session. It’s still possible to override this token by passing a token explicitly for a request.

consistency sets the consistency mode to use by default for all reads that support the consistency option. It’s still possible to override this by passing explicitly for a given request. consistency can be either ‘default’, ‘consistent’ or ‘stale’.

dc is the datacenter that this agent will communicate with. By default, the datacenter of the host is used.

verify is whether to verify the SSL certificate for HTTPS requests

cert client side certificates for HTTPS requests

Parameters:
  • args – positional arguments to pass to consul.base.Consul

  • kwargs – keyword arguments, with cert, ca_cert and token removed, passed to consul.base.Consul

connect(*args: Any, **kwargs: Any) HTTPClient
http_connect(*args: Any, **kwargs: Any) HTTPClient
reload_config(config: Dict[str, Any]) None
exception patroni.dcs.consul.ConsulError(value: Any)

Bases: DCSError

exception patroni.dcs.consul.ConsulInternalError

Bases: ConsulException

An internal Consul server error occurred

class patroni.dcs.consul.HTTPClient(host: str = '127.0.0.1', port: int = 8500, token: str | None = None, scheme: str = 'http', verify: bool = True, cert: str | None = None, ca_cert: str | None = None)

Bases: object

__init__(host: str = '127.0.0.1', port: int = 8500, token: str | None = None, scheme: str = 'http', verify: bool = True, cert: str | None = None, ca_cert: str | None = None) None
static response(response: HTTPResponse) Response
set_read_timeout(timeout: float) None
set_ttl(ttl: int) bool
property ttl: int
uri(path: str, params: None | Dict[str, Any] | List[Tuple[str, Any]] | Tuple[Tuple[str, Any], ...] = None) str
exception patroni.dcs.consul.InvalidSession

Bases: ConsulException

invalid session

exception patroni.dcs.consul.InvalidSessionTTL

Bases: ConsulException

Session TTL is too small or too big

class patroni.dcs.consul.Response(code, headers, body, content)

Bases: NamedTuple

_asdict()

Return a new dict which maps field names to their values.

_field_defaults = {}
_fields = ('code', 'headers', 'body', 'content')
classmethod _make(iterable)

Make a new Response object from a sequence or iterable

_replace(**kwds)

Return a new Response object replacing specified fields with new values

body: str

Alias for field number 2

code: int

Alias for field number 0

content: bytes

Alias for field number 3

headers: Mapping[str, str] | Mapping[bytes, bytes] | None

Alias for field number 1

patroni.dcs.consul.catch_consul_errors(func: Callable[[...], Any]) Callable[[...], Any]
patroni.dcs.consul.force_if_last_failed(func: Callable[[...], Any]) Callable[[...], Any]
patroni.dcs.consul.service_name_from_scope_name(scope_name: str) str

Translate scope name to service name which can be used in dns.

230 = 253 - len(‘replica.’) - len(‘.service.consul’)