...
All admin messages listed below are required to be sent only to Controller broker. Only controller will process such messages. If Admin message is sent to an ordinary broker a special error code is returned (code 22
). In case of other failure during processing message AdminRequestFailedError
is returned [2].
Error | Code | Description |
---|---|---|
| 21 | Unexpected error occurred while processing Admin request. |
NotControllerForAdminRequest | 22 | Target broker (id=<this_broker_id>) is not serving a controller's role. |
ClusterMetadata Schema
Cluster Metadata Request
ClusterMetadataRequest => |
Cluster Metadata Response
ClusterMetadataResponse => ErrorCode [Broker] ?(Controller)
Broker => NodeId Host Port NodeId => int32
Port => int32 Controller => Broker |
ClusteMetadataRequest
is a request with no arguments.
ClusterMetadataResponse
holds error code (0
in case of successful result), list of brokers in cluster and optionally broker serving a Controller's role (returning empty Controller most likely means either error during request processing or cluster being in some intermediate state).
ClusterMetadataRequest
is required for admin clients to get the Kafka brokers, specifically the controller's location, as only controller may execute admin command [2].
Topic Admin Schema
...
CreateTopicResponse => ErrorCode ?(ErrorDescription) ErrorCode => int16 ErrorDescription => string |
CreateTopicRequest
requires topic name and either (partitions+replicas) or replicas assignment to create topic (validation is done on server side). You can also specify topic-level configs to create topic with (to use default set an empty array).
CreateTopicResponse
is fairly simple - you receive error code (0
as always identifies NO_ERROR
) and optionally error description. Usually it will hold the higher level exception that happened during command execution.
Alter Topic Request
AlterTopicRequest => TopicName ?(Partitions) ?(ReplicaAssignment) [AddedConfigEntry] [DeletedConfig] TopicName => string Partitions => int32 ReplicaAssignment => string AddedConfigEntry => ConfigKey ConfigValue ConfigKey => string ConfigValue => string Deleted Config => string |
Alter Topic Response
AlterTopicResponse => ErrorCode ?(ErrorDescription) ErrorCode => int16 ErrorDescription => string
|
AlterTopicRequest
is similar to previous, to specify topic level settings that should be removed, use DeletedConfig
array (just setting keys). User can provide new partitions value, replica assignment or both.AlterTopicResponse
is similar to CreateTopicResponse
.
Delete Topic Request
DeleteTopicRequest => TopicName TopicName => string |
Delete Topic Response
DeleteTopicResponse => ErrorCode ?(ErrorDescription) ErrorCode => int16 ErrorDescription => string
|
DeleteTopicRequest
requires only topic name which should be deleted.
DeleteTopicResponse
is similar to CreateTopicResponse
.
Describe Topic Request
DescribeTopicRequest => TopicNameTopicName => string |
Describe Topic Response
DescribeTopicResponse => ErrorCode ?(ErrorDescription) ?(TopicDescription) ErrorCode => int16 ErrorDescription => string TopicDescription => TopicName TopicConfigDetails [TopicPartitionDetails] TopicName => string TopicConfigDetails => Partitions ReplicationFactor [ConfigEntry] Partitions => int32 ReplicationFactor => int32 ConfigEntry => string string TopicPartitionsDetails => PartitionId ?(Leader) [Replica] [ISR] PartitionId => int32 Leader => int32 Replica => int32 ISR => int32 |
DescribeTopicRequest
requires only topic name.DescribeTopicResponse
besides errorCode and optional errorDescription which are used in the same way as in previous messages, holds optional (non empty if execution was successful) TopicDescription
structure. See table below for details:
Field | Description |
---|---|
TopicName | The name of the topic for which description is provided. |
TopicConfigDetails | A structure that holds basic replication details. |
Partitions | Number of partitions in give topic. |
Config | Topic-level setting and value which was overridden. |
TopicPartitionDetails | List describing replication details for each partition. |
PartitionId | Id of the partition. |
Leader | Optional broekr-leader id for the described partition. |
Replicas | List of broker ids serving a replica's role for the partition. |
ISR | Same as replicas but includes only brokers that are known to be "in-sync" |
List Topics Request
ListTopicsRequest => |
List Topics Response
ListTopicsResponse => ErrorCode ?(ErrorDescription) ?(TopicsList) ErrorCode => int16 ErrorDescription => string TopicsList => [TopicName] TopicName => string |
ListTopicsRequest
is a request with no arguments.ListTopicsResponse
besides errorCode and optional errorDescription which are used in the same way as in previous messages, holds optional (non empty if execution was successful) two list of topic names - one for deleted topics (marked for deletion) and the second one for ordinary, alive topics.
Replication Commands Schema
Reassign Partitions
Reassign Partitions Request
ReassignPartitionRequest => ManualAssignment ManualAssignment => string |
Reassign Partitions Response
ReassignPartitionResponse => ErrorCode ?(ErrorDescription) ErrorCode => int16 ErrorDescription => string
|
ReassignPartitionsRequest
requires manual partition assignment string. Parsing / validation is done on server. This request will only initiate partition reassignment and return immediately. It is client's responsibility to block the user continually sending VerifyReassignPartitionsRequest
to check reassignment status. The format is the following:
{
"partitions": [
{"topic": "foo",
"partition": 1,
"replicas": [1,2,3] }
],
"version":1
}
ReassignPartitionResponse
is similar to CreateTopicResponse
.
Verify Reassign Partitions Request
VerifyReassignPartitionRequest => ManualAssignment ManualAssignment => string |
Verify Reassign Partitions Response
VerifyReassignPartitionResponse => [ReasignmnetResult] ErrorCode ?(ErrorDescription) ReasignmnetResult => TopicAndPartition ResultCode TopicAndPartition => string int32 ResultCode => int16 ErrorCode => int16 ErrorDescription => string |
VerifyReassignPartitionsRequest
requires manual partition assignment string as with ReassignPartitionsRequest
which status is verified by this request.
VerifyReassignPartitionResponse
as with other Admin request may return error code and optional error description in case of failure. Otherwise a reassignment result map is returned. It holds reassignment status (-1
- reassignment failed, 0
- in progress, 1
- completed successfully).
Preferred Replica Leader Election
Preferred Replica Leader Election Request
PreferredReplicaLeaderElectionRequest => PartitionsSerialized PartitionsSerialized => string |
Preferred Replica Leader Election Response
PreferredReplicaLeaderElectionResponse => ErrorCode ?(ErrorDescription) ErrorCode => int16 ErrorDescription => string
|
PreferredReplicaLeaderEleactionRequest
initiates preferred replica leader election procedure, similar to ReassignPartitionsRequest
this request in intended to be non-blocking. The schema consist of one optional field - partitions in serialized form (json) for which procedure should be started. The format is the following:{"partitions":
[
{"topic": "foo", "partition": 1},
{"topic": "foobar", "partition": 2}
]
}
PreferredReplicaLeaderElectionResponse
is similar to CreateTopicResponse
.
Status of the procedure may be checked with DescribeTopicRequest
- the head of replicas
list field and leader
broker should be the same.
2. Server-side Admin Request handlers
All incoming request will be handled by specific helper classes called from KafkaApis
- TopicCommandHelper
for topic admin commands, ReassignPartitionsCommandHelper
and PreferredReplicaLeaderElectionCommandHelper
.
All these commands are already implemented as standalone CLI tools, so there is no need to re-implement them. Unfortunately most of command classes are strongly coupled with CLI logic and can hardly be refactored, so for now (before we remove standalone CLI commands) most likely the logic from those classes will be extracted and copied to separate classes (as proposed - TopicCommandHelper
etc).
3. Admin Client
This component is intended to be a Kafka out-of-box client implementation for Admin commands.
Admin client will use Kafka NetworkClient
facility from /clients
for cluster communication. Besides Admin commands, client will handle cluster metadata cache and will provide user with a convenient way of handling long running commands (as e.g. reassign partitions).
Proposed API:
Code Block | ||||||
---|---|---|---|---|---|---|
| ||||||
public class AdminClient {
/**
* A producer is instantiated by providing a set of key-value pairs as configuration
*
* @param properties settings related to Network client and at least one broker from KafkaCluster to connect to
*/
public AdminClient(Properties properties)
/**
* Create topic with given number of partitions and replication factor, replica assignment will be handled by Kafka cluster
*
* @throws ApiException
*/
public void createTopic(String topicName, int partitions, int replicationFactor, List<ConfigEntry> configs) throws ApiException;
/**
* Create topic with specified replica assignment (number of partitions and replication factor will be taken
* from replica assignment string)
*
* @throws ApiException
*/
public void createTopic(String topicName, String replicaAssignment, List<ConfigEntry> configs) throws ApiException;
/**
* Alter existing topic partitions and/or replica assignment among Kafka brokers
*
* @throws ApiException
*/
public abstract void alterTopic(String topicName, Integer partitions, String replicaAssignment,
List<ConfigEntry> addedConfigs, List<String> deletedConfigs) throws ApiException;
/**
* Delete Kafka topic by name
*
* @throws ApiException
*/
public abstract void deleteTopic(String topicName) throws ApiException;
/**
* List all existing topics in Kafka cluster
*
* @throws ApiException
*/
public abstract List<String> listTopics() throws ApiException;
/**
* Request replication information about Kafka topic
*
* @throws ApiException
*/
public abstract DescribeTopicOutput describeTopic(String topicName) throws ApiException;
/**
* Initiate long-running reassign partitions procedure
*
* @param partitionsReassignment manual partitions assignment string (according to ReassignPartitionsCommand)
* @return future of the reassignment result which is completed once server-side partitions reassignment has succeeded or
* an error occurred so that partitions reassignment cannot be started
* @throws ApiException
*/
public abstract Future<ReassignPartitionsResponse> reassignPartitions(String partitionsReassignment) throws ApiException;
/**
* Check the interim status of the partitions reassignment
*
* @param partitionsReassignment manual partitions assignment string (according to ReassignPartitionsCommand)
* @return partition to reassignment result code (completed, in-progress, failed)
* @throws ApiException
*/
public abstract Map<TopicPartition, Short> verifyReassignPartitions(String partitionsReassignment) throws ApiException;
/**
* Initiate long-running preferred replica leader election procedure
*
* @param partitions serialized partitions for which preferred replica leader election will be started
* (according to PreferredReplicaLeaderElectionCommand)
* @return future of the election result which is completed once server-side preferred replica is elected for provided partitions or
* an error has occurred
* @throws ApiException
*/
public abstract Future<PreferredReplicaLeaderElectionResponse> preferredReplicaLeaderElection(String partitions) throws ApiException;
/**
* Check the interim status of the preferred replica leader election
*
* @param partitions for which preferred replica leader election was started (according to PreferredReplicaLeaderElectionCommand)
* @return partition to reassignment result code (completed, in-progress, failed)
* @throws ApiException
*/
public abstract VerifyPreferredReplicaLeaderElectionResponse verifyPreferredReplicaLeaderElection(String partitions)
throws ApiException;
/**
* Send Admin request and return response counterpart
*
* @param adminRequest AbstractAdminRequest subtype
* @param <T> concrete AdminRequestType
* @return response counterpart
* @throws ApiException
*/
private <T extends AbstractAdminResponse> T sendAdminRequest(AbstractAdminRequest<T> adminRequest) throws ApiException;
private void updateClusterMetadata() throws Exception;
} |
Installation
This is an instruction how to build and start Kafka Command Line Tool (hereinafter - Shell). The implementation is in progress under KAFKA-1694.
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