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class
bootstrap_servers
– ‘host[:port]’ string (or list of ‘host[:port]’
strings) that the consumer should contact to bootstrap initial
cluster metadata. This does not have to be the full node list.
It just needs to have at least one broker that will respond to a
Metadata API Request. Default port is 9092. If no servers are
specified, will default to localhost:9092.
client_id
(
str
) – A name for this client. This string is passed in
each request to servers and can be used to identify specific
server-side log entries that correspond to this client. Also
submitted to GroupCoordinator for logging with respect to
consumer group administration. Default: ‘kafka-python-{version}’
group_id
(
str
or
None
) – The name of the consumer group to join for dynamic
partition assignment (if enabled), and to use for fetching and
committing offsets. If None, auto-partition assignment (via
group coordinator) and offset commits are disabled.
Default: None
key_deserializer
(
callable
) – Any callable that takes a
raw message key and returns a deserialized key.
value_deserializer
(
callable
) – Any callable that takes a
raw message value and returns a deserialized value.
fetch_min_bytes
(
int
) – Minimum amount of data the server should
return for a fetch request, otherwise wait up to
fetch_max_wait_ms for more data to accumulate. Default: 1.
fetch_max_wait_ms
(
int
) – The maximum amount of time in milliseconds
the server will block before answering the fetch request if
there isn’t sufficient data to immediately satisfy the
requirement given by fetch_min_bytes. Default: 500.
fetch_max_bytes
(
int
) – The maximum amount of data the server should
return for a fetch request. This is not an absolute maximum, if the
first message in the first non-empty partition of the fetch is
larger than this value, the message will still be returned to
ensure that the consumer can make progress. NOTE: consumer performs
fetches to multiple brokers in parallel so memory usage will depend
on the number of brokers containing partitions for the topic.
Supported Kafka version >= 0.10.1.0. Default: 52428800 (50 MB).
max_partition_fetch_bytes
(
int
) – The maximum amount of data
per-partition the server will return. The maximum total memory
used for a request = #partitions * max_partition_fetch_bytes.
This size must be at least as large as the maximum message size
the server allows or else it is possible for the producer to
send messages larger than the consumer can fetch. If that
happens, the consumer can get stuck trying to fetch a large
message on a certain partition. Default: 1048576.
request_timeout_ms
(
int
) – Client request timeout in milliseconds.
Default: 305000.
retry_backoff_ms
(
int
) – Milliseconds to backoff when retrying on
errors. Default: 100.
reconnect_backoff_ms
(
int
) – The amount of time in milliseconds to
wait before attempting to reconnect to a given host.
Default: 50.
reconnect_backoff_max_ms
(
int
) – The maximum amount of time in
milliseconds to backoff/wait when reconnecting to a broker that has
repeatedly failed to connect. If provided, the backoff per host
will increase exponentially for each consecutive connection
failure, up to this maximum. Once the maximum is reached,
reconnection attempts will continue periodically with this fixed
rate. To avoid connection storms, a randomization factor of 0.2
will be applied to the backoff resulting in a random range between
20% below and 20% above the computed value. Default: 1000.
max_in_flight_requests_per_connection
(
int
) – Requests are pipelined
to kafka brokers up to this number of maximum requests per
broker connection. Default: 5.
auto_offset_reset
(
str
) – A policy for resetting offsets on
OffsetOutOfRange errors: ‘earliest’ will move to the oldest
available message, ‘latest’ will move to the most recent. Any
other value will raise the exception. Default: ‘latest’.
enable_auto_commit
(
bool
) – If True , the consumer’s offset will be
periodically committed in the background. Default: True.
auto_commit_interval_ms
(
int
) – Number of milliseconds between automatic
offset commits, if enable_auto_commit is True. Default: 5000.
default_offset_commit_callback
(
callable
) – Called as
callback(offsets, response) response will be either an Exception
or an OffsetCommitResponse struct. This callback can be used to
trigger custom actions when a commit request completes.
check_crcs
(
bool
) – Automatically check the CRC32 of the records
consumed. This ensures no on-the-wire or on-disk corruption to
the messages occurred. This check adds some overhead, so it may
be disabled in cases seeking extreme performance. Default: True
metadata_max_age_ms
(
int
) – The period of time in milliseconds after
which we force a refresh of metadata, even if we haven’t seen any
partition leadership changes to proactively discover any new
brokers or partitions. Default: 300000
partition_assignment_strategy
(
list
) – List of objects to use to
distribute partition ownership amongst consumer instances when
group management is used.
Default: [RangePartitionAssignor, RoundRobinPartitionAssignor]
max_poll_records
(
int
) – The maximum number of records returned in a
single call to
max_poll_interval_ms
(
int
) – The maximum delay between invocations of
session_timeout_ms
(
int
) – The timeout used to detect failures when
using Kafka’s group management facilities. The consumer sends
periodic heartbeats to indicate its liveness to the broker. If
no heartbeats are received by the broker before the expiration of
this session timeout, then the broker will remove this consumer
from the group and initiate a rebalance. Note that the value must
be in the allowable range as configured in the broker configuration
by group.min.session.timeout.ms and group.max.session.timeout.ms.
Default: 10000
heartbeat_interval_ms
(
int
) – The expected time in milliseconds
between heartbeats to the consumer coordinator when using
Kafka’s group management facilities. Heartbeats are used to ensure
that the consumer’s session stays active and to facilitate
rebalancing when new consumers join or leave the group. The
value must be set lower than session_timeout_ms, but typically
should be set no higher than 1/3 of that value. It can be
adjusted even lower to control the expected time for normal
rebalances. Default: 3000
receive_buffer_bytes
(
int
) – The size of the TCP receive buffer
(SO_RCVBUF) to use when reading data. Default: None (relies on
system defaults). The java client defaults to 32768.
send_buffer_bytes
(
int
) – The size of the TCP send buffer
(SO_SNDBUF) to use when sending data. Default: None (relies on
system defaults). The java client defaults to 131072.
socket_options
(
list
) – List of tuple-arguments to socket.setsockopt
to apply to broker connection sockets. Default:
[(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)]
consumer_timeout_ms
(
int
) – number of milliseconds to block during
message iteration before raising StopIteration (i.e., ending the
iterator). Default block forever [float(‘inf’)].
security_protocol
(
str
) – Protocol used to communicate with brokers.
Valid values are: PLAINTEXT, SSL, SASL_PLAINTEXT, SASL_SSL.
Default: PLAINTEXT.
ssl_context
(
ssl.SSLContext
) – Pre-configured SSLContext for wrapping
socket connections. If provided, all other ssl_* configurations
will be ignored. Default: None.
ssl_check_hostname
(
bool
) – Flag to configure whether ssl handshake
should verify that the certificate matches the brokers hostname.
Default: True.
ssl_cafile
(
str
) – Optional filename of ca file to use in certificate
verification. Default: None.
ssl_certfile
(
str
) – Optional filename of file in pem format containing
the client certificate, as well as any ca certificates needed to
establish the certificate’s authenticity. Default: None.
ssl_keyfile
(
str
) – Optional filename containing the client private key.
Default: None.
ssl_password
(
str
) – Optional password to be used when loading the
certificate chain. Default: None.
ssl_crlfile
(
str
) – Optional filename containing the CRL to check for
certificate expiration. By default, no CRL check is done. When
providing a file, only the leaf certificate will be checked against
this CRL. The CRL can only be checked with Python 3.4+ or 2.7.9+.
Default: None.
ssl_ciphers
(
str
) – optionally set the available ciphers for ssl
connections. It should be a string in the OpenSSL cipher list
format. If no cipher can be selected (because compile-time options
or other configuration forbids use of all the specified ciphers),
an ssl.SSLError will be raised. See ssl.SSLContext.set_ciphers
api_version
(
tuple
) –
(0, 9) enables full group coordination features with automatic
partition assignment and rebalancing,
(0, 8, 2) enables kafka-storage offset commits with manual
partition assignment only,
(0, 8, 1) enables zookeeper-storage offset commits with manual
partition assignment only,
(0, 8, 0) enables basic functionality but requires manual
partition assignment and offset management.
api_version_auto_timeout_ms
(
int
) – number of milliseconds to throw a
timeout exception from the constructor when checking the broker
api version. Only applies if api_version set to None.
connections_max_idle_ms
– Close idle connections after the number of
milliseconds specified by this config. The broker closes idle
connections after connections.max.idle.ms, so this avoids hitting
unexpected socket disconnected errors on the client.
Default: 540000
metric_reporters
(
list
) – A list of classes to use as metrics reporters.
Implementing the AbstractMetricsReporter interface allows plugging
in classes that will be notified of new metric creation. Default: []
metrics_num_samples
(
int
) – The number of samples maintained to compute
metrics. Default: 2
metrics_sample_window_ms
(
int
) – The maximum age in milliseconds of
samples used to compute metrics. Default: 30000
selector
(
selectors.BaseSelector
) – Provide a specific selector
implementation to use for I/O multiplexing.
Default: selectors.DefaultSelector
exclude_internal_topics
(
bool
) – Whether records from internal topics
(such as offsets) should be exposed to the consumer. If set to True
the only way to receive records from an internal topic is
subscribing to it. Requires 0.10+ Default: True
sasl_mechanism
(
str
) – Authentication mechanism when security_protocol
is configured for SASL_PLAINTEXT or SASL_SSL. Valid values are:
PLAIN, GSSAPI, OAUTHBEARER, SCRAM-SHA-256, SCRAM-SHA-512.
sasl_plain_username
(
str
) – username for sasl PLAIN and SCRAM authentication.
Required if sasl_mechanism is PLAIN or one of the SCRAM mechanisms.
sasl_plain_password
(
str
) – password for sasl PLAIN and SCRAM authentication.
Required if sasl_mechanism is PLAIN or one of the SCRAM mechanisms.
sasl_kerberos_service_name
(
str
) – Service name to include in GSSAPI
sasl mechanism handshake. Default: ‘kafka’
sasl_kerberos_domain_name
(
str
) – kerberos domain name to use in GSSAPI
sasl mechanism handshake. Default: one of bootstrap servers
sasl_oauth_token_provider
(
AbstractTokenProvider
) – OAuthBearer token provider
instance. (See kafka.oauth.abstract). Default: None
kafka.
KafkaConsumer
(
*topics
,
**configs
)
[source]
¶
Consume records from a Kafka cluster.
The consumer will transparently handle the failure of servers in the Kafka cluster, and adapt as topic-partitions are created or migrate between brokers. It also interacts with the assigned kafka Group Coordinator node to allow multiple consumers to load balance consumption of topics (requires kafka >= 0.9.0.0).
The consumer is not thread safe and should not be shared across threads.
Parameters:
*topics
(
str
) – optional list of topics to subscribe to. If not set,
call
subscribe()
or
assign()
before consuming records.
poll()
. Default: 500
poll()
when using consumer group
management. This places an upper bound on the amount of time that
the consumer can be idle before fetching more records. If
poll()
is not called before expiration
of this timeout, then the consumer is considered failed and the
group will rebalance in order to reassign the partitions to another
member. Default 300000
Specify which Kafka API version to use. If set to None, the client will attempt to infer the broker version by probing various APIs. Different versions enable different functionality.
Examples
Default: None
Warning
It is not possible to use both manual partition assignment with
assign()
and group assignment with
subscribe()
.
This interface does not support incremental assignment and will replace the previous assignment (if there was one).
Manual topic assignment through this method does not use the consumer’s group management functionality. As such, there will be no rebalance operation triggered when group membership or cluster and topic metadata change.
assignment
(
)
[source]
¶
Get the TopicPartitions currently assigned to this consumer.
If partitions were directly assigned using
assign()
, then this will simply return the
same partitions that were previously assigned. If topics were
subscribed using
subscribe()
, then this will
give the set of topic partitions currently assigned to the consumer
(which may be None if the assignment hasn’t happened yet, or if the
partitions are in the process of being reassigned).
beginning_offsets
(
partitions
)
[source]
¶
Get the first offset for the given partitions.
This method does not change the current consumer position of the partitions.
This method may block indefinitely if the partition does not exist.
Raises:-
UnsupportedVersionError– If the broker does not support looking up the offsets by timestamp. -
KafkaTimeoutError– If fetch failed in request_timeout_ms.
Keyword Arguments:
autocommit
(
bool
) – If auto-commit is configured for this consumer,
this optional flag causes the consumer to attempt to commit any
pending consumed offsets prior to close. Default: True
-
Commit offsets to kafka, blocking until success or error.
This commits offsets only to Kafka. The offsets committed using this API will be used on the first fetch after every rebalance and also on startup. As such, if you need to store offsets in anything other than Kafka, this API should not be used. To avoid re-processing the last message read if a consumer is restarted, the committed offset should be the next message your application should consume, i.e.: last_offset + 1.
Blocks until either the commit succeeds or an unrecoverable error is encountered (in which case it is thrown to the caller).
Currently only supports kafka-topic offset storage (not zookeeper).
Parameters: offsets ( dict , optional ) – {TopicPartition: OffsetAndMetadata} dict to commit with the configured group_id. Defaults to currently consumed offsets for all subscribed partitions.commit_async( offsets=None , callback=None ) [source] ¶ -
Commit offsets to kafka asynchronously, optionally firing callback.
This commits offsets only to Kafka. The offsets committed using this API will be used on the first fetch after every rebalance and also on startup. As such, if you need to store offsets in anything other than Kafka, this API should not be used. To avoid re-processing the last message read if a consumer is restarted, the committed offset should be the next message your application should consume, i.e.: last_offset + 1.
This is an asynchronous call and will not block. Any errors encountered are either passed to the callback (if provided) or discarded.
Parameters:- offsets ( dict , optional ) – {TopicPartition: OffsetAndMetadata} dict to commit with the configured group_id. Defaults to currently consumed offsets for all subscribed partitions.
- callback ( callable , optional ) – Called as callback(offsets, response) with response as either an Exception or an OffsetCommitResponse struct. This callback can be used to trigger custom actions when a commit request completes. Returns:
-
Get the last committed offset for the given partition.
This offset will be used as the position for the consumer in the event of a failure.
This call may block to do a remote call if the partition in question isn’t assigned to this consumer or if the consumer hasn’t yet initialized its cache of committed offsets.
Parameters:- partition ( TopicPartition ) – The partition to check.
- metadata ( bool , optional ) – If True, return OffsetAndMetadata struct instead of offset int. Default: False. Returns:
-
Get the last offset for the given partitions. The last offset of a partition is the offset of the upcoming message, i.e. the offset of the last available message + 1.
This method does not change the current consumer position of the partitions.
This method may block indefinitely if the partition does not exist.
Raises:-
UnsupportedVersionError– If the broker does not support looking up the offsets by timestamp. -
KafkaTimeoutError– If fetch failed in request_timeout_ms -
Last known highwater offset for a partition.
A highwater offset is the offset that will be assigned to the next message that is produced. It may be useful for calculating lag, by comparing with the reported position. Note that both position and highwater refer to the next offset – i.e., highwater offset is one greater than the newest available message.
Highwater offsets are returned in FetchResponse messages, so will not be available if no FetchRequests have been sent for this partition Parameters: partition ( TopicPartition ) – Partition to check Returns:Offset if available Return type:int or None
metrics( raw=False ) [source] ¶ -
Get metrics on consumer performance.
This is ported from the Java Consumer, for details see: https://kafka.apache.org/documentation/#consumer_monitoring
Warning
This is an unstable interface. It may change in future releases without warning.
offsets_for_times( timestamps ) [source] ¶ -
Look up the offsets for the given partitions by timestamp. The returned offset for each partition is the earliest offset whose timestamp is greater than or equal to the given timestamp in the corresponding partition.
This is a blocking call. The consumer does not have to be assigned the partitions.
If the message format version in a partition is before 0.10.0, i.e. the messages do not have timestamps,
Nonewill be returned for that partition.Nonewill also be returned for the partition if there are no messages in it.This method may block indefinitely if the partition does not exist.
Parameters:timestamps ( dict ) –
Returns:{TopicPartition: int}mapping from partition to the timestamp to look up. Unit should be milliseconds since beginning of the epoch (midnight Jan 1, 1970 (UTC))OffsetAndTimestamp}``: mapping from partition to the timestamp and offset of the first message with timestamp greater than or equal to the target timestamp.
Return type:`` {TopicPartition
Raises:-
ValueError– If the target timestamp is negative -
UnsupportedVersionError– If the broker does not support looking up the offsets by timestamp. -
KafkaTimeoutError– If fetch failed in request_timeout_ms -
This method first checks the local metadata cache for information about the topic. If the topic is not found (either because the topic does not exist, the user is not authorized to view the topic, or the metadata cache is not populated), then it will issue a metadata update call to the cluster.
pause( *partitions ) [source] ¶ -
Suspend fetching from the requested partitions.
Future calls to
poll()will not return any records from these partitions until they have been resumed usingresume().Note: This method does not affect partition subscription. In particular, it does not cause a group rebalance when automatic assignment is used.
poll( timeout_ms=0 , max_records=None , update_offsets=True ) [source] ¶ -
Fetch data from assigned topics / partitions.
Records are fetched and returned in batches by topic-partition. On each poll, consumer will try to use the last consumed offset as the starting offset and fetch sequentially. The last consumed offset can be manually set through
seek()or automatically set as the last committed offset for the subscribed list of partitions.Incompatible with iterator interface – use one or the other, not both.
Parameters:- timeout_ms ( int , optional ) – Milliseconds spent waiting in poll if data is not available in the buffer. If 0, returns immediately with any records that are available currently in the buffer, else returns empty. Must not be negative. Default: 0
-
max_records
(
int
,
optional
) – The maximum number of records returned
in a single call to
poll(). Default: Inherit value from max_poll_records.
Returns:
- Topic to list of records since the last fetch for the
-
subscribed list of topics and partitions.
seek( partition , offset ) [source] ¶ -
Manually specify the fetch offset for a TopicPartition.
Overrides the fetch offsets that the consumer will use on the next
poll(). If this API is invoked for the same partition more than once, the latest offset will be used on the nextpoll().Note: You may lose data if this API is arbitrarily used in the middle of consumption to reset the fetch offsets.
Parameters: *partitions – Optionally provide specific TopicPartitions, otherwise default to all assigned partitions. Raises:AssertionError– If any partition is not currently assigned, or if no partitions are assigned. Parameters: *partitions – Optionally provide specific TopicPartitions, otherwise default to all assigned partitions. Raises:AssertionError– If any partition is not currently assigned, or if no partitions are assigned.subscribe( topics=() , pattern=None , listener=None ) [source] ¶ -
Subscribe to a list of topics, or a topic regex pattern.
Partitions will be dynamically assigned via a group coordinator. Topic subscriptions are not incremental: this list will replace the current assignment (if there is one).
This method is incompatible with
Parameters:assign().- topics ( list ) – List of topics for subscription.
- pattern ( str ) – Pattern to match available topics. You must provide either topics or pattern, but not both.
-
listener
(
ConsumerRebalanceListener
) –
Optionally include listener callback, which will be called before and after each rebalance operation.
As part of group management, the consumer will keep track of the list of consumers that belong to a particular group and will trigger a rebalance operation if one of the following events trigger:
- Number of partitions change for any of the subscribed topics
- Topic is created or deleted
- An existing member of the consumer group dies
- A new member is added to the consumer group
-
IllegalStateError– If called after previously callingassign(). -
AssertionError– If neither topics or pattern is provided. -
TypeError– If listener is not a ConsumerRebalanceListener. -
Get all topics the user is authorized to view. This will always issue a remote call to the cluster to fetch the latest information.
When any of these events are triggered, the provided listener will be invoked first to indicate that the consumer’s assignment has been revoked, and then again when the new assignment has been received. Note that this listener will immediately override any listener set in a previous call to subscribe. It is guaranteed, however, that the partitions revoked/assigned through this interface are from topics subscribed in this call.
topics( ) [source] ¶
partitions_for_topic( topic ) [source] ¶ -
highwater( partition ) [source] ¶ -
The last committed offset (int or OffsetAndMetadata), or None if there was no prior commit.
end_offsets( partitions ) [source] ¶
kafka.future.Future
committed( partition , metadata=False ) [source] ¶
commit
(
offsets=None
)
[source]
¶
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