Zookeeper
- By Canonical Data Platform
- Databases
| Channel | Revision | Published | Runs on |
|---|---|---|---|
| latest/stable | 53 | 29 Nov 2021 | |
| latest/candidate | 56 | 29 Nov 2021 | |
| latest/beta | 56 | 29 Nov 2021 | |
| latest/edge | 98 | 20 Apr 2023 | |
| 3/stable | 126 | 27 Feb 2024 | |
| 3/candidate | 126 | 27 Feb 2024 | |
| 3/beta | 126 | 27 Feb 2024 | |
| 3/edge | 131 | 24 Apr 2024 |
juju deploy zookeeper --channel 3/stable
Deploy universal operators easily with Juju, the Universal Operator Lifecycle Manager.
Platform:
charms.zookeeper.v0.client
-
- Last updated 11 Aug 2023
- Revision Library version 0.6
ZooKeeperManager and ZooKeeperClient classes
ZooKeeperManager provides an interface for performing actions that requires
a connection to the current ZK quorum leader, e.g updating zNodes, ACLs and quorum members.
On __init__, it loops through all passed hosts, attempts a ZooKeeperClient connection, and
checks leadership of each unit, storing the current quorum leader host as an attribute.
In most cases, custom Exceptions raised by ZooKeeperManager should trigger an event.defer(),
as they indicate that the servers are not ready to have actions performed upon them just yet.
ZooKeeperClient serves as a handler for managing a ZooKeeper client connection to a
single unit. It's methods contain common 4lw commands, and functionality to read/write
to specific zNodes.
It is not expected to use this class from directly from charm code,
but to instead use the ZooKeeperManager class to perform it's actions on the ZK servers.
Instances of ZooKeeperManager are to be created by methods in either the Charm itself,
or from another library.
Example usage for ZooKeeperManager:
def update_cluster(new_members: List[str], event: EventBase) -> None:
try:
zk = ZooKeeperManager(
hosts=["10.141.73.20", "10.141.73.21"],
client_port=2181,
username="super",
password="password"
)
current_quorum_members = zk.server_members
servers_to_remove = list(current_quorum_members - new_members)
zk.remove_members(servers_to_remove)
servers_to_add = sorted(new_members - current_quorum_members)
zk.add_members(servers_to_add)
except (
MembersSyncingError,
MemberNotReadyError,
QuorumLeaderNotFoundError,
) as e:
logger.info(str(e))
event.defer()
return
Index
class MembersSyncingError
Description
Generic exception for when quorum members are syncing data. None
class MemberNotReadyError
Description
Generic exception for when a zk unit can't be connected to or is not broadcasting. None
class QuorumLeaderNotFoundError
Description
Generic exception for when there are no zk leaders in the app. None
class ZooKeeperManager
Description
Handler for performing ZK commands. None
Methods
ZooKeeperManager. __init__( self , hosts , username: str , password: str , client_port: int , use_ssl: bool , keyfile_path , keyfile_password , certfile_path )
ZooKeeperManager. get_leader( self )
Attempts to find the current ZK quorum leader.
Returns
String of the host for the quorum leader
Description
In the case when there is a leadership election, this may fail. When this happens, we attempt 1 retry after 3 seconds.
ZooKeeperManager. server_members( self )
The current members within the ZooKeeper quorum.
Returns
A set of ZK member strings e.g {"server.1=10.141.78.207:2888:3888:participant;0.0.0.0:2181"}
ZooKeeperManager. config_version( self )
The current config version for ZooKeeper.
Returns
The zookeeper config version decoded from base16
ZooKeeperManager. members_syncing( self )
Flag to check if any quorum members are currently syncing data.
Returns
True if any members are syncing. Otherwise False.
ZooKeeperManager. members_broadcasting( self )
Flag to check if any quorum members are currently broadcasting.
Returns
True if any members are currently broadcasting. Otherwise False.
ZooKeeperManager. add_members( self , members )
Adds new members to the members' dynamic config.
ZooKeeperManager. remove_members( self , members )
Removes members from the members' dynamic config.
ZooKeeperManager. leader_znodes( self , path: str )
Grabs all children zNodes for a path on the current quorum leader.
Arguments
the 'root' path to search from
Returns
Set of all nested child zNodes
ZooKeeperManager. create_znode_leader( self , path: str , acls )
Creates a new zNode on the current quorum leader with given ACLs.
Arguments
the zNode path to set
the ACLs to be set on that path
ZooKeeperManager. set_acls_znode_leader( self , path: str , acls )
Updates ACLs for an existing zNode on the current quorum leader.
Arguments
the zNode path to update
the new ACLs to be set on that path
ZooKeeperManager. delete_znode_leader( self , path: str )
Deletes a zNode path from the current quorum leader.
Arguments
the zNode path to delete
ZooKeeperManager. get_version( self )
Get ZooKeeper service version from srvr 4lw.
Returns
String of ZooKeeper service version
class ZooKeeperClient
Description
Handler for ZooKeeper connections and running 4lw client commands. None
Methods
ZooKeeperClient. __init__( self , host: str , client_port: int , username: str , password: str , use_ssl: bool , keyfile_path , keyfile_password , certfile_path )
ZooKeeperClient. __enter__( self )
ZooKeeperClient. __exit__( self , object_type , value , traceback )
ZooKeeperClient. config( self )
Retrieves the dynamic config for a ZooKeeper service.
Returns
Tuple of the decoded config list, and decoded config version
ZooKeeperClient. srvr( self )
Retrieves attributes returned from the 'srvr' 4lw command.
Returns
Mapping of field and setting returned from srvr
ZooKeeperClient. mntr( self )
Retrieves attributes returned from the 'mntr' 4lw command.
Returns
Mapping of field and setting returned from mntr
ZooKeeperClient. is_ready( self )
Flag to confirm connected ZooKeeper server is connected and broadcasting.
Returns
True if server is broadcasting. Otherwise False.
ZooKeeperClient. get_all_znode_children( self , path: str )
Recursively gets all children for a given parent znode path.
Arguments
the desired parent znode path to recurse
Returns
Set of all nested children znode paths for the given parent
ZooKeeperClient. delete_znode( self , path: str )
Drop znode and all it's children from ZK tree.
Arguments
the desired znode path to delete
ZooKeeperClient. create_znode( self , path: str , acls )
Create new znode.
Arguments
the desired znode path to create
the acls for the new znode
ZooKeeperClient. get_acls( self , path: str )
Gets acls for a desired znode path.
Arguments
the desired znode path
Returns
List of the acls set for the given znode
ZooKeeperClient. set_acls( self , path: str , acls )
Sets acls for a desired znode path.
Arguments
the desired znode path
the acls to set to the given znode