Kafka Producer Configuration Reference for Confluent Platform

Confluent Platform is a data-streaming platform that completes Kafka with advanced capabilities designed to help accelerate application development and connectivity for enterprise use cases.

This topic provides Kafka and Confluent Platform producer configuration parameters. The configuration parameters are organized by order of importance, ranked from high to low.

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To learn more about producers in Kafka, see Kafka Producer for Confluent Platform or Course: Apache Kafka 101: Producers. You can find code samples for producers in different languages in these guides.

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bootstrap.servers

A list of host/port pairs used to establish the initial connection to the Kafka cluster. Clients use this list to bootstrap and discover the full set of Kafka brokers. While the order of servers in the list does not matter, we recommend including more than one server to ensure resilience if any servers are down. This list does not need to contain the entire set of brokers, as Kafka clients automatically manage and update connections to the cluster efficiently. This list must be in the form host1:port1,host2:port2,....

Type:	list
Default:
Valid Values:
Importance:	high

key.serializer

Serializer class for key that implements the org.apache.kafka.common.serialization.Serializer interface.

Type:	class
Default:
Valid Values:
Importance:	high

value.serializer

Serializer class for value that implements the org.apache.kafka.common.serialization.Serializer interface.

Type:	class
Default:
Valid Values:
Importance:	high

buffer.memory

The total bytes of memory the producer can use to buffer records waiting to be sent to the server. If records are sent faster than they can be delivered to the server the producer will block for max.block.ms after which it will fail with an exception.

This setting should correspond roughly to the total memory the producer will use, but is not a hard bound since not all memory the producer uses is used for buffering. Some additional memory will be used for compression (if compression is enabled) as well as for maintaining in-flight requests.

Type:	long
Default:	33554432
Valid Values:	[0,…]
Importance:	high

compression.type

The compression type for all data generated by the producer. The default is none (i.e. no compression). Valid values are none, gzip, snappy, lz4, or zstd. Compression is of full batches of data, so the efficacy of batching will also impact the compression ratio (more batching means better compression).

Type:	string
Default:	none
Valid Values:	[none, gzip, snappy, lz4, zstd]
Importance:	high

retries

Number of times to retry a request that fails with a transient error. Setting a value greater than zero will cause the client to resend any record whose send fails with a potentially transient error. Requests will be retried this many times until they succeed, fail with a non-transient error, or the delivery.timeout.ms expires. Note that this automatic retry will simply resend the same record upon receiving the error. Setting a value of zero will disable this automatic retry behaviour, so that the transient errors will be propagated to the application to be handled. Users should generally prefer to leave this config unset and instead use delivery.timeout.ms to control retry behavior.

Enabling idempotence requires this config value to be greater than 0. If conflicting configurations are set and idempotence is not explicitly enabled, idempotence is disabled.

Allowing retries while setting enable.idempotence to false and max.in.flight.requests.per.connection to greater than 1 will potentially change the ordering of records because if two batches are sent to a single partition, and the first fails and is retried but the second succeeds, then the records in the second batch may appear first.

Type:	int
Default:	2147483647
Valid Values:	[0,…,2147483647]
Importance:	high

ssl.key.password

The password of the private key in the key store file or the PEM key specified in ‘ssl.keystore.key’.

Type:	password
Default:	null
Valid Values:
Importance:	high

ssl.keystore.certificate.chain

Certificate chain in the format specified by ‘ssl.keystore.type’. Default SSL engine factory supports only PEM format with a list of X.509 certificates

Type:	password
Default:	null
Valid Values:
Importance:	high

ssl.keystore.key

Private key in the format specified by ‘ssl.keystore.type’. Default SSL engine factory supports only PEM format with PKCS#8 keys. If the key is encrypted, key password must be specified using ‘ssl.key.password’

Type:	password
Default:	null
Valid Values:
Importance:	high

ssl.keystore.location

The location of the key store file. This is optional for client and can be used for two-way authentication for client.

Type:	string
Default:	null
Valid Values:
Importance:	high

ssl.keystore.password

The store password for the key store file. This is optional for client and only needed if ‘ssl.keystore.location’ is configured. Key store password is not supported for PEM format.

Type:	password
Default:	null
Valid Values:
Importance:	high

ssl.truststore.certificates

Trusted certificates in the format specified by ‘ssl.truststore.type’. Default SSL engine factory supports only PEM format with X.509 certificates.

Type:	password
Default:	null
Valid Values:
Importance:	high

ssl.truststore.location

The location of the trust store file.

Type:	string
Default:	null
Valid Values:
Importance:	high

ssl.truststore.password

The password for the trust store file. If a password is not set, trust store file configured will still be used, but integrity checking is disabled. Trust store password is not supported for PEM format.

Type:	password
Default:	null
Valid Values:
Importance:	high

batch.size

The producer will attempt to batch records together into fewer requests whenever multiple records are being sent to the same partition. This helps performance on both the client and the server. This configuration controls the default batch size in bytes.

No attempt will be made to batch records larger than this size.

Requests sent to brokers will contain multiple batches, one for each partition with data available to be sent.

A small batch size will make batching less common and may reduce throughput (a batch size of zero will disable batching entirely). A very large batch size may use memory a bit more wastefully as we will always allocate a buffer of the specified batch size in anticipation of additional records.

Note: This setting gives the upper bound of the batch size to be sent. If we have fewer than this many bytes accumulated for this partition, we will ‘linger’ for the linger.ms time waiting for more records to show up. This linger.ms setting defaults to 5, which means the producer will wait for 5ms or until the record batch is of batch.size (whichever happens first) before sending the record batch. Note that broker backpressure can result in a higher effective linger time than this setting. The default changed from 0 to 5 in Apache Kafka 4.0 as the efficiency gains from larger batches typically result in similar or lower producer latency despite the increased linger.

Type:	int
Default:	16384
Valid Values:	[0,…]
Importance:	medium

client.dns.lookup

Controls how the client uses DNS lookups. If set to use_all_dns_ips, connect to each returned IP address in sequence until a successful connection is established. After a disconnection, the next IP is used. Once all IPs have been used once, the client resolves the IP(s) from the hostname again (both the JVM and the OS cache DNS name lookups, however). If set to resolve_canonical_bootstrap_servers_only, resolve each bootstrap address into a list of canonical names. After the bootstrap phase, this behaves the same as use_all_dns_ips.

Type:	string
Default:	use_all_dns_ips
Valid Values:	[use_all_dns_ips, resolve_canonical_bootstrap_servers_only]
Importance:	medium

client.id

An id string to pass to the server when making requests. The purpose of this is to be able to track the source of requests beyond just ip/port by allowing a logical application name to be included in server-side request logging.

Type:	string
Default:	“”
Valid Values:
Importance:	medium

compression.gzip.level

The compression level to use if compression.type is set to gzip.

Type:	int
Default:	-1
Valid Values:	[1,…,9] or -1
Importance:	medium

compression.lz4.level

The compression level to use if compression.type is set to lz4.

Type:	int
Default:	9
Valid Values:	[1,…,17]
Importance:	medium

compression.zstd.level

The compression level to use if compression.type is set to zstd.

Type:	int
Default:	3
Valid Values:	[-131072,…,22]
Importance:	medium

connections.max.idle.ms

Close idle connections after the number of milliseconds specified by this config.

Type:	long
Default:	540000 (9 minutes)
Valid Values:
Importance:	medium

delivery.timeout.ms

An upper bound on the time to report success or failure after a call to send() returns. This limits the total time that a record will be delayed prior to sending, the time to await acknowledgement from the broker (if expected), and the time allowed for retriable send failures. The producer may report failure to send a record earlier than this config if either an unrecoverable error is encountered, the retries have been exhausted, or the record is added to a batch which reached an earlier delivery expiration deadline. The value of this config should be greater than or equal to the sum of request.timeout.ms and linger.ms.

Type:	int
Default:	120000 (2 minutes)
Valid Values:	[0,…]
Importance:	medium

linger.ms

The producer groups together any records that arrive in between request transmissions into a single batched request. Normally this occurs only under load when records arrive faster than they can be sent out. However in some circumstances the client may want to reduce the number of requests even under moderate load. This setting accomplishes this by adding a small amount of artificial delay—that is, rather than immediately sending out a record, the producer will wait for up to the given delay to allow other records to be sent so that the sends can be batched together. This can be thought of as analogous to Nagle’s algorithm in TCP. This setting gives the upper bound on the delay for batching: once we get batch.size worth of records for a partition it will be sent immediately regardless of this setting, however if we have fewer than this many bytes accumulated for this partition we will ‘linger’ for the specified time waiting for more records to show up. This setting defaults to 5 (i.e. 5ms delay). Increasing linger.ms=50, for example, would have the effect of reducing the number of requests sent but would add up to 50ms of latency to records sent in the absence of load.The default changed from 0 to 5 in Apache Kafka 4.0 as the efficiency gains from larger batches typically result in similar or lower producer latency despite the increased linger.

Type:	long
Default:	5
Valid Values:	[0,…]
Importance:	medium

max.block.ms

The configuration controls how long the KafkaProducer’s send(), partitionsFor(), initTransactions(), sendOffsetsToTransaction(), commitTransaction() and abortTransaction() methods will block. For send() this timeout bounds the total time waiting for both metadata fetch and buffer allocation (blocking in the user-supplied serializers or partitioner is not counted against this timeout). For partitionsFor() this timeout bounds the time spent waiting for metadata if it is unavailable. The transaction-related methods always block, but may timeout if the transaction coordinator could not be discovered or did not respond within the timeout.

Type:	long
Default:	60000 (1 minute)
Valid Values:	[0,…]
Importance:	medium

max.request.size

The maximum size of a request in bytes. This setting will limit the number of record batches the producer will send in a single request to avoid sending huge requests. This is also effectively a cap on the maximum uncompressed record batch size. Note that the server has its own cap on the record batch size (after compression if compression is enabled) which may be different from this.

Type:	int
Default:	1048576
Valid Values:	[0,…]
Importance:	medium

partitioner.class

Determines which partition to send a record to when records are produced. Available options are:

• If not set, the default partitioning logic is used. This strategy send records to a partition until at least batch.size bytes is produced to the partition. It works with the strategy:If no partition is specified but a key is present, choose a partition based on a hash of the key.If no partition or key is present, choose the sticky partition that changes when at least batch.size bytes are produced to the partition.

• org.apache.kafka.clients.producer.RoundRobinPartitioner: A partitioning strategy where each record in a series of consecutive records is sent to a different partition, regardless of whether the ‘key’ is provided or not, until partitions run out and the process starts over again. Note: There’s a known issue that will cause uneven distribution when a new batch is created. See KAFKA-9965 for more detail.

Implementing the org.apache.kafka.clients.producer.Partitioner interface allows you to plug in a custom partitioner.

Type:	class
Default:	null
Valid Values:
Importance:	medium

partitioner.ignore.keys

When set to ‘true’ the producer won’t use record keys to choose a partition. If ‘false’, producer would choose a partition based on a hash of the key when a key is present. Note: this setting has no effect if a custom partitioner is used.

Type:	boolean
Default:	false
Valid Values:
Importance:	medium

receive.buffer.bytes

The size of the TCP receive buffer (SO_RCVBUF) to use when reading data. If the value is -1, the OS default will be used.

Type:	int
Default:	32768 (32 kibibytes)
Valid Values:	[-1,…]
Importance:	medium

request.timeout.ms

The configuration controls the maximum amount of time the client will wait for the response of a request. If the response is not received before the timeout elapses the client will resend the request if necessary or fail the request if retries are exhausted. This should be larger than replica.lag.time.max.ms (a broker configuration) to reduce the possibility of message duplication due to unnecessary producer retries.

Type:	int
Default:	30000 (30 seconds)
Valid Values:	[0,…]
Importance:	medium

sasl.client.callback.handler.class

The fully qualified name of a SASL client callback handler class that implements the AuthenticateCallbackHandler interface.

Type:	class
Default:	null
Valid Values:
Importance:	medium

sasl.jaas.config

JAAS login context parameters for SASL connections in the format used by JAAS configuration files. JAAS configuration file format is described here. The format for the value is: loginModuleClass controlFlag (optionName=optionValue)*;. For brokers, the config must be prefixed with listener prefix and SASL mechanism name in lower-case. For example, listener.name.sasl_ssl.scram-sha-256.sasl.jaas.config=com.example.ScramLoginModule required;

Type:	password
Default:	null
Valid Values:
Importance:	medium

sasl.jaas.config.jndi.allowlist

This system property is used to allow list the JNDI properties that can be configured in the SASL JAAS configuration. This property accepts comma-separated list of JNDI properties. By default, all of the properties prefixed with java.naming are denied.If users want to use any of the java.naming JNDI properties, they need to explicitly set the system property as shown below to allow list the same. We advise the users to validate configurations and only allow trusted JNDI properties. For more details`CVE-2023-25194 <https://kafka.apache.org/cve-list#CVE-2023-25194>`__ To add more JNDI properties, explicitly update the system property with comma-separated values. For example, to allow java.naming.factory.initial and java.naming.provider.url, set the property as follows: -Dsasl.jaas.config.jndi.allowlist=java.naming.factory.initial,java.naming.provider.url

Type:	string
Default:	null
Valid Values:
Importance:	medium

sasl.kerberos.service.name

The Kerberos principal name that Kafka runs as. This can be defined either in Kafka’s JAAS config or in Kafka’s config.

Type:	string
Default:	null
Valid Values:
Importance:	medium

sasl.login.callback.handler.class

The fully qualified name of a SASL login callback handler class that implements the AuthenticateCallbackHandler interface. For brokers, login callback handler config must be prefixed with listener prefix and SASL mechanism name in lower-case. For example, listener.name.sasl_ssl.scram-sha-256.sasl.login.callback.handler.class=com.example.CustomScramLoginCallbackHandler

Type:	class
Default:	null
Valid Values:
Importance:	medium

sasl.login.class

The fully qualified name of a class that implements the Login interface. For brokers, login config must be prefixed with listener prefix and SASL mechanism name in lower-case. For example, listener.name.sasl_ssl.scram-sha-256.sasl.login.class=com.example.CustomScramLogin

Type:	class
Default:	null
Valid Values:
Importance:	medium

sasl.mechanism

SASL mechanism used for client connections. This may be any mechanism for which a security provider is available. GSSAPI is the default mechanism.

Type:	string
Default:	GSSAPI
Valid Values:
Importance:	medium

sasl.oauthbearer.assertion.algorithm

The algorithm the Apache Kafka client should use to sign the assertion sent to the identity provider. It is also used as the value of the OAuth alg (Algorithm) header in the JWT assertion.

Note: If a value for sasl.oauthbearer.assertion.file is provided, this configuration will be ignored.

Type:	string
Default:	RS256
Valid Values:	(case insensitive) [ES256, RS256]
Importance:	medium

sasl.oauthbearer.assertion.claim.aud

The JWT aud (Audience) claim which will be included in the client JWT assertion created locally.

Note: If a value for sasl.oauthbearer.assertion.file is provided, this configuration will be ignored.

Type:	string
Default:	null
Valid Values:
Importance:	medium

sasl.oauthbearer.assertion.claim.iss

The value to be used as the iss (Issuer) claim which will be included in the client JWT assertion created locally.

Note: If a value for sasl.oauthbearer.assertion.file is provided, this configuration will be ignored.

Type:	string
Default:	null
Valid Values:
Importance:	medium

sasl.oauthbearer.assertion.claim.jti.include

Flag that determines if the JWT assertion should generate a unique ID for the JWT and include it in the jti (JWT ID) claim.

Note: If a value for sasl.oauthbearer.assertion.file is provided, this configuration will be ignored.

Type:	boolean
Default:	false
Valid Values:
Importance:	medium

sasl.oauthbearer.assertion.claim.sub

The value to be used as the sub (Subject) claim which will be included in the client JWT assertion created locally.

Note: If a value for sasl.oauthbearer.assertion.file is provided, this configuration will be ignored.

Type:	string
Default:	null
Valid Values:
Importance:	medium

sasl.oauthbearer.assertion.file

File that contains a pre-generated JWT assertion.

The underlying implementation caches the file contents to avoid the performance hit of loading the file on each access. The caching mechanism will detect whenthe file changes to allow for the file to be reloaded on modifications. This allows for “live” assertion rotation without restarting the Kafka client.

The file contains the assertion in the serialized, three part JWT format:

See RFC 7519 and RFC 7515 for more details on the JWT and JWS formats.

Note: If a value for sasl.oauthbearer.assertion.file is provided, all other sasl.oauthbearer.assertion.* configurations are ignored.

Type:	string
Default:	null
Valid Values:
Importance:	medium

sasl.oauthbearer.assertion.private.key.file

File that contains a private key in the standard PEM format which is used to sign the JWT assertion sent to the identity provider.

The underlying implementation caches the file contents to avoid the performance hit of loading the file on each access. The caching mechanism will detect when the file changes to allow for the file to be reloaded on modifications. This allows for “live” private key rotation without restarting the Kafka client.

Note: If a value for sasl.oauthbearer.assertion.file is provided, this configuration will be ignored.

Type:	string
Default:	null
Valid Values:
Importance:	medium

sasl.oauthbearer.assertion.private.key.passphrase

The optional passphrase to decrypt the private key file specified by sasl.oauthbearer.assertion.private.key.file.

Note: If the file referred to by sasl.oauthbearer.assertion.private.key.file is modified on the file system at runtime and it was created with a different passphrase than it was previously, the client will not be able to access the private key file because the passphrase is now out of date. For that reason, when using private key passphrases, either use the same passphrase each time, or—for improved security—restart the Kafka client using the new passphrase configuration.

Note: If a value for sasl.oauthbearer.assertion.file is provided, this configuration will be ignored.

Type:	password
Default:	null
Valid Values:
Importance:	medium

sasl.oauthbearer.assertion.template.file

This optional configuration specifies the file containing the JWT headers and/or payload claims to be used when creating the JWT assertion.

Not all identity providers require the same set of claims; some may require a given claim while others may prohibit it. In order to provide the most flexibility, this configuration allows the user to provide the static header values and claims that are to be included in the JWT.

Note: If a value for sasl.oauthbearer.assertion.file is provided, this configuration will be ignored.

Type:	string
Default:	null
Valid Values:
Importance:	medium

sasl.oauthbearer.client.credentials.client.id

The ID (defined in/by the OAuth identity provider) to identify the client requesting the token.

The client ID was previously stored as part of the sasl.jaas.config configuration with the key clientId. For backward compatibility, the clientId JAAS option can still be used, but it is deprecated and will be removed in a future version.

Order of precedence:

Type:	string
Default:	null
Valid Values:
Importance:	medium

sasl.oauthbearer.client.credentials.client.secret

The secret (defined by either the user or preassigned, depending on the identity provider) of the client requesting the token.

The client secret was previously stored as part of the sasl.jaas.config configuration with the key clientSecret. For backward compatibility, the clientSecret JAAS option can still be used, but it is deprecated and will be removed in a future version.

Order of precedence:

Type:	password
Default:	null
Valid Values:
Importance:	medium

sasl.oauthbearer.jwks.endpoint.url

The OAuth/OIDC provider URL from which the provider’s JWKS (JSON Web Key Set) can be retrieved. The URL can be HTTP(S)-based or file-based. If the URL is HTTP(S)-based, the JWKS data will be retrieved from the OAuth/OIDC provider via the configured URL on broker startup. All then-current keys will be cached on the broker for incoming requests. If an authentication request is received for a JWT that includes a “kid” header claim value that isn’t yet in the cache, the JWKS endpoint will be queried again on demand. However, the broker polls the URL every sasl.oauthbearer.jwks.endpoint.refresh.ms milliseconds to refresh the cache with any forthcoming keys before any JWT requests that include them are received. If the URL is file-based, the broker will load the JWKS file from a configured location on startup. In the event that the JWT includes a “kid” header value that isn’t in the JWKS file, the broker will reject the JWT and authentication will fail.

Type:	string
Default:	null
Valid Values:
Importance:	medium

sasl.oauthbearer.jwt.retriever.class

The fully-qualified class name of a JwtRetriever implementation used to request tokens from the identity provider.

The default configuration value represents a class that maintains backward compatibility with previous versions of Apache Kafka. The default implementation uses the configuration to determine which concrete implementation to create.

Other implementations that are provided include:

Type:	class
Default:	org.apache.kafka.common.security.oauthbearer.DefaultJwtRetriever
Valid Values:
Importance:	medium

sasl.oauthbearer.jwt.validator.class

The fully-qualified class name of a JwtValidator implementation used to validate the JWT from the identity provider.

The default validator (org.apache.kafka.common.security.oauthbearer.DefaultJwtValidator) maintains backward compatibility with previous versions of Apache Kafka. The default validator uses configuration to determine which concrete implementation to create.

The built-in JwtValidator implementations are:

Type:	class
Default:	org.apache.kafka.common.security.oauthbearer.DefaultJwtValidator
Valid Values:
Importance:	medium

sasl.oauthbearer.scope

This is the level of access a client application is granted to a resource or API which is included in the token request. If provided, it should match one or more scopes configured in the identity provider.

The scope was previously stored as part of the sasl.jaas.config configuration with the key scope. For backward compatibility, the scope JAAS option can still be used, but it is deprecated and will be removed in a future version.

Order of precedence:

Type:	string
Default:	null
Valid Values:
Importance:	medium

sasl.oauthbearer.token.endpoint.url

The URL for the OAuth/OIDC identity provider. If the URL is HTTP(S)-based, it is the issuer’s token endpoint URL to which requests will be made to login based on the configuration in sasl.oauthbearer.jwt.retriever.class. If the URL is file-based, it specifies a file containing an access token (in JWT serialized form) issued by the OAuth/OIDC identity provider to use for authorization.

Type:	string
Default:	null
Valid Values:
Importance:	medium

security.protocol

Protocol used to communicate with brokers.

Type:	string
Default:	PLAINTEXT
Valid Values:	(case insensitive) [SASL_SSL, PLAINTEXT, SSL, SASL_PLAINTEXT]
Importance:	medium

send.buffer.bytes

The size of the TCP send buffer (SO_SNDBUF) to use when sending data. If the value is -1, the OS default will be used.

Type:	int
Default:	131072 (128 kibibytes)
Valid Values:	[-1,…]
Importance:	medium

socket.connection.setup.timeout.max.ms

The maximum amount of time the client will wait for the socket connection to be established. The connection setup timeout will increase exponentially for each consecutive connection failure up to this maximum. To avoid connection storms, a randomization factor of 0.2 will be applied to the timeout resulting in a random range between 20% below and 20% above the computed value.

Type:	long
Default:	30000 (30 seconds)
Valid Values:
Importance:	medium

socket.connection.setup.timeout.ms

The amount of time the client will wait for the socket connection to be established. If the connection is not built before the timeout elapses, clients will close the socket channel. This value is the initial backoff value and will increase exponentially for each consecutive connection failure, up to the socket.connection.setup.timeout.max.ms value.

Type:	long
Default:	10000 (10 seconds)
Valid Values:
Importance:	medium

ssl.enabled.protocols

The list of protocols enabled for SSL connections. The default is ‘TLSv1.2,TLSv1.3’. This means that clients and servers will prefer TLSv1.3 if both support it and fallback to TLSv1.2 otherwise (assuming both support at least TLSv1.2). This default should be fine for most use cases. If this configuration is set to an empty list, Kafka will use the protocols enabled by default in the underlying SSLEngine, which may include additional protocols depending on the JVM version. Also see the config documentation for ssl.protocol to understand how it can impact the TLS version negotiation behavior.

Type:	list
Default:	TLSv1.2,TLSv1.3
Valid Values:
Importance:	medium

ssl.keystore.type

The file format of the key store file. This is optional for client. The values currently supported by the default ssl.engine.factory.class are [JKS, PKCS12, PEM].

Type:	string
Default:	JKS
Valid Values:
Importance:	medium

ssl.protocol

The SSL protocol used to generate the SSLContext. The default is ‘TLSv1.3’, which should be fine for most use cases. A typical alternative to the default is ‘TLSv1.2’. Allowed values for this config are dependent on the JVM. Clients using the defaults for this config and ‘ssl.enabled.protocols’ will downgrade to ‘TLSv1.2’ if the server does not support ‘TLSv1.3’. If this config is set to ‘TLSv1.2’, however, clients will not use ‘TLSv1.3’ even if it is one of the values in ssl.enabled.protocols and the server only supports ‘TLSv1.3’.

Type:	string
Default:	TLSv1.3
Valid Values:
Importance:	medium

ssl.provider

The name of the security provider used for SSL connections. Default value is the default security provider of the JVM.

Type:	string
Default:	null
Valid Values:
Importance:	medium

ssl.truststore.type

The file format of the trust store file. The values currently supported by the default ssl.engine.factory.class are [JKS, PKCS12, PEM].

Type:	string
Default:	JKS
Valid Values:
Importance:	medium

acks

The number of acknowledgments the producer requires the leader to have received before considering a request complete. This controls the durability of records that are sent. The following settings are allowed:

• acks=0 If set to zero then the producer will not wait for any acknowledgment from the server at all. The record will be immediately added to the socket buffer and considered sent. No guarantee can be made that the server has received the record in this case, and the retries configuration will not take effect (as the client won’t generally know of any failures). The offset given back for each record will always be set to -1.

• acks=1 This will mean the leader will write the record to its local log but will respond without awaiting full acknowledgement from all followers. In this case should the leader fail immediately after acknowledging the record but before the followers have replicated it then the record will be lost.

• acks=all This means the leader will wait for the full set of in-sync replicas to acknowledge the record. This guarantees that the record will not be lost as long as at least one in-sync replica remains alive. This is the strongest available guarantee. This is equivalent to the acks=-1 setting.

Note that enabling idempotence requires this config value to be ‘all’. If conflicting configurations are set and idempotence is not explicitly enabled, idempotence is disabled.

Type:	string
Default:	all
Valid Values:	[all, -1, 0, 1]
Importance:	low

config.providers

Comma-separated alias names for classes implementing the ConfigProvider interface. This enables loading configuration data (such as passwords, API keys, and other credentials) from external sources. For example, see Configuration Providers.

Type:	list
Default:	“”
Valid Values:
Importance:	low

confluent.selectable.plugin.class

The plugin class to use to create a Selector to use with NetworkClient. We currently have two selectors, one TCP based and one HTTP/2 based. An empty value for this config will default to TCP based Selector.

Type:	class
Default:	null
Valid Values:
Importance:	low

enable.idempotence

When set to ‘true’, the producer will ensure that exactly one copy of each message is written in the stream. If ‘false’, producer retries due to broker failures, etc., may write duplicates of the retried message in the stream. Note that enabling idempotence requires max.in.flight.requests.per.connection to be less than or equal to 5 (with message ordering preserved for any allowable value), retries to be greater than 0, and acks must be ‘all’.

Idempotence is enabled by default if no conflicting configurations are set. If conflicting configurations are set and idempotence is not explicitly enabled, idempotence is disabled. If idempotence is explicitly enabled and conflicting configurations are set, a ConfigException is thrown.

Type:	boolean
Default:	true
Valid Values:
Importance:	low

enable.metrics.push

Whether to enable pushing of client metrics to the cluster, if the cluster has a client metrics subscription which matches this client.

Type:	boolean
Default:	true
Valid Values:
Importance:	low

interceptor.classes

A list of classes to use as interceptors. Implementing the org.apache.kafka.clients.producer.ProducerInterceptor interface allows you to intercept (and possibly mutate) the records received by the producer before they are published to the Kafka cluster. By default, there are no interceptors.

Type:	list
Default:	“”
Valid Values:
Importance:	low

max.in.flight.requests.per.connection

The maximum number of unacknowledged requests the client will send on a single connection before blocking. Note that if this configuration is set to be greater than 1 and enable.idempotence is set to false, there is a risk of message reordering after a failed send due to retries (i.e., if retries are enabled); if retries are disabled or if enable.idempotence is set to true, ordering will be preserved. Additionally, enabling idempotence requires the value of this configuration to be less than or equal to 5, because broker only retains at most 5 batches for each producer. If the value is more than 5, previous batches may be removed on broker side.

Type:	int
Default:	5
Valid Values:	[1,…]
Importance:	low

metadata.max.age.ms

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.

Type:	long
Default:	300000 (5 minutes)
Valid Values:	[0,…]
Importance:	low

metadata.max.idle.ms

Controls how long the producer will cache metadata for a topic that’s idle. If the elapsed time since a topic was last produced to exceeds the metadata idle duration, then the topic’s metadata is forgotten and the next access to it will force a metadata fetch request.

Type:	long
Default:	300000 (5 minutes)
Valid Values:	[5000,…]
Importance:	low

metadata.recovery.rebootstrap.trigger.ms

If a client configured to rebootstrap using metadata.recovery.strategy=rebootstrap is unable to obtain metadata from any of the brokers in the last known metadata for this interval, client repeats the bootstrap process using bootstrap.servers configuration.

Type:	long
Default:	300000 (5 minutes)
Valid Values:	[0,…]
Importance:	low

metadata.recovery.strategy

Controls how the client recovers when none of the brokers known to it is available. If set to none, the client fails. If set to rebootstrap, the client repeats the bootstrap process using bootstrap.servers. Rebootstrapping is useful when a client communicates with brokers so infrequently that the set of brokers may change entirely before the client refreshes metadata. Metadata recovery is triggered when all last-known brokers appear unavailable simultaneously. Brokers appear unavailable when disconnected and no current retry attempt is in-progress. Consider increasing reconnect.backoff.ms and reconnect.backoff.max.ms and decreasing socket.connection.setup.timeout.ms and socket.connection.setup.timeout.max.ms for the client. Rebootstrap is also triggered if connection cannot be established to any of the brokers for metadata.recovery.rebootstrap.trigger.ms milliseconds or if server requests rebootstrap.

Type:	string
Default:	rebootstrap
Valid Values:	(case insensitive) [REBOOTSTRAP, NONE]
Importance:	low

metric.reporters

A list of classes to use as metrics reporters. Implementing the org.apache.kafka.common.metrics.MetricsReporter interface allows plugging in classes that will be notified of new metric creation. When custom reporters are set and org.apache.kafka.common.metrics.JmxReporter is needed, it has to be explicitly added to the list.

Type:	list
Default:	org.apache.kafka.common.metrics.JmxReporter
Valid Values:
Importance:	low

metrics.num.samples

The number of samples maintained to compute metrics.

Type:	int
Default:	2
Valid Values:	[1,…]
Importance:	low

metrics.recording.level

The highest recording level for metrics. It has three levels for recording metrics - info, debug, and trace. INFO level records only essential metrics necessary for monitoring system performance and health. It collects vital data without gathering too much detail, making it suitable for production environments where minimal overhead is desired.DEBUG level records most metrics, providing more detailed information about the system’s operation. It’s useful for development and testing environments where you need deeper insights to debug and fine-tune the application.TRACE level records all possible metrics, capturing every detail about the system’s performance and operation. It’s best for controlled environments where in-depth analysis is required, though it can introduce significant overhead.

Type:	string
Default:	INFO
Valid Values:	[INFO, DEBUG, TRACE]
Importance:	low

metrics.sample.window.ms

The window of time a metrics sample is computed over.

Type:	long
Default:	30000 (30 seconds)
Valid Values:	[0,…]
Importance:	low

partitioner.adaptive.partitioning.enable

When set to ‘true’, the producer will try to adapt to broker performance and produce more messages to partitions hosted on faster brokers. If ‘false’, the producer will try to distribute messages uniformly. Note: this setting has no effect if a custom partitioner is used.

Type:	boolean
Default:	true
Valid Values:
Importance:	low

partitioner.availability.timeout.ms

If a broker cannot process produce requests from a partition for partitioner.availability.timeout.ms time, the partitioner treats that partition as not available. If the value is 0, this logic is disabled. Note: this setting has no effect if a custom partitioner is used or partitioner.adaptive.partitioning.enable is set to ‘false’.

Type:	long
Default:	0
Valid Values:	[0,…]
Importance:	low

reconnect.backoff.max.ms

The maximum amount of time in milliseconds to 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. After calculating the backoff increase, 20% random jitter is added to avoid connection storms.

Type:	long
Default:	1000 (1 second)
Valid Values:	[0,…]
Importance:	low

reconnect.backoff.ms

The base amount of time to wait before attempting to reconnect to a given host. This avoids repeatedly connecting to a host in a tight loop. This backoff applies to all connection attempts by the client to a broker. This value is the initial backoff value and will increase exponentially for each consecutive connection failure, up to the reconnect.backoff.max.ms value.

Type:	long
Default:	50
Valid Values:	[0,…]
Importance:	low

retry.backoff.max.ms

The maximum amount of time in milliseconds to wait when retrying a request to the broker that has repeatedly failed. If provided, the backoff per client will increase exponentially for each failed request, up to this maximum. To prevent all clients from being synchronized upon retry, a randomized jitter with a factor of 0.2 will be applied to the backoff, resulting in the backoff falling within a range between 20% below and 20% above the computed value. If retry.backoff.ms is set to be higher than retry.backoff.max.ms, then retry.backoff.max.ms will be used as a constant backoff from the beginning without any exponential increase

Type:	long
Default:	1000 (1 second)
Valid Values:	[0,…]
Importance:	low

retry.backoff.ms

The amount of time to wait before attempting to retry a failed request to a given topic partition. This avoids repeatedly sending requests in a tight loop under some failure scenarios. This value is the initial backoff value and will increase exponentially for each failed request, up to the retry.backoff.max.ms value.

Type:	long
Default:	100
Valid Values:	[0,…]
Importance:	low

sasl.kerberos.kinit.cmd

Kerberos kinit command path.

Type:	string
Default:	/usr/bin/kinit
Valid Values:
Importance:	low

sasl.kerberos.min.time.before.relogin

Login thread sleep time between refresh attempts.

Type:	long
Default:	60000
Valid Values:
Importance:	low

sasl.kerberos.ticket.renew.jitter

Percentage of random jitter added to the renewal time.

Type:	double
Default:	0.05
Valid Values:
Importance:	low

sasl.kerberos.ticket.renew.window.factor

Login thread will sleep until the specified window factor of time from last refresh to ticket’s expiry has been reached, at which time it will try to renew the ticket.

Type:	double
Default:	0.8
Valid Values:
Importance:	low

sasl.login.connect.timeout.ms

The (optional) value in milliseconds for the external authentication provider connection timeout. Currently applies only to OAUTHBEARER.

Type:	int
Default:	null
Valid Values:
Importance:	low

sasl.login.read.timeout.ms

The (optional) value in milliseconds for the external authentication provider read timeout. Currently applies only to OAUTHBEARER.

Type:	int
Default:	null
Valid Values:
Importance:	low

sasl.login.refresh.buffer.seconds

The amount of buffer time before credential expiration to maintain when refreshing a credential, in seconds. If a refresh would otherwise occur closer to expiration than the number of buffer seconds then the refresh will be moved up to maintain as much of the buffer time as possible. Legal values are between 0 and 3600 (1 hour); a default value of 300 (5 minutes) is used if no value is specified. This value and sasl.login.refresh.min.period.seconds are both ignored if their sum exceeds the remaining lifetime of a credential. Currently applies only to OAUTHBEARER.

Type:	short
Default:	300
Valid Values:	[0,…,3600]
Importance:	low

sasl.login.refresh.min.period.seconds

The desired minimum time for the login refresh thread to wait before refreshing a credential, in seconds. Legal values are between 0 and 900 (15 minutes); a default value of 60 (1 minute) is used if no value is specified. This value and sasl.login.refresh.buffer.seconds are both ignored if their sum exceeds the remaining lifetime of a credential. Currently applies only to OAUTHBEARER.

Type:	short
Default:	60
Valid Values:	[0,…,900]
Importance:	low

sasl.login.refresh.window.factor

Login refresh thread will sleep until the specified window factor relative to the credential’s lifetime has been reached, at which time it will try to refresh the credential. Legal values are between 0.5 (50%) and 1.0 (100%) inclusive; a default value of 0.8 (80%) is used if no value is specified. Currently applies only to OAUTHBEARER.

Type:	double
Default:	0.8
Valid Values:	[0.5,…,1.0]
Importance:	low

sasl.login.refresh.window.jitter

The maximum amount of random jitter relative to the credential’s lifetime that is added to the login refresh thread’s sleep time. Legal values are between 0 and 0.25 (25%) inclusive; a default value of 0.05 (5%) is used if no value is specified. Currently applies only to OAUTHBEARER.

Type:	double
Default:	0.05
Valid Values:	[0.0,…,0.25]
Importance:	low

sasl.login.retry.backoff.max.ms

The (optional) value in milliseconds for the maximum wait between login attempts to the external authentication provider. Login uses an exponential backoff algorithm with an initial wait based on the sasl.login.retry.backoff.ms setting and will double in wait length between attempts up to a maximum wait length specified by the sasl.login.retry.backoff.max.ms setting. Currently applies only to OAUTHBEARER.

Type:	long
Default:	10000 (10 seconds)
Valid Values:
Importance:	low

sasl.login.retry.backoff.ms

The (optional) value in milliseconds for the initial wait between login attempts to the external authentication provider. Login uses an exponential backoff algorithm with an initial wait based on the sasl.login.retry.backoff.ms setting and will double in wait length between attempts up to a maximum wait length specified by the sasl.login.retry.backoff.max.ms setting. Currently applies only to OAUTHBEARER.

Type:	long
Default:	100
Valid Values:
Importance:	low

sasl.oauthbearer.assertion.claim.exp.minutes

The (Optional) expiration time for the client assertion in minutesThe default value is 5 minutes

Type:	int
Default:	5
Valid Values:
Importance:	low

sasl.oauthbearer.assertion.claim.exp.seconds

The number of seconds in the future for which the JWT is valid. The value is used to determine the JWT exp (Expiration) claim based on the current system time when the JWT is created.

The formula to generate the exp claim is very simple:

Let:<br><br>  x = the current timestamp in seconds, on client<br>  y = the value of this configuration<br><br>Then:<br><br>  exp = x + y<br>

Note: If a value for sasl.oauthbearer.assertion.file is provided, this configuration will be ignored.

Type:	int
Default:	300
Valid Values:	[0,…,86400]
Importance:	low

sasl.oauthbearer.assertion.claim.nbf.include

The (optional) setting for specifying whether to include “not before” (nbf) claim or notIf set to true, nbf claim with (current time - 1 minute) will be included in the client assertion

Type:	boolean
Default:	false
Valid Values:
Importance:	low

sasl.oauthbearer.assertion.claim.nbf.seconds

The number of seconds in the past from which the JWT is valid. The value is used to determine the JWT nbf (Not Before) claim based on the current system time when the JWT is created.

The formula to generate the nbf claim is very simple:

Let:<br><br>  x = the current timestamp in seconds, on client<br>  y = the value of this configuration<br><br>Then:<br><br>  nbf = x - y<br>

Note: If a value for sasl.oauthbearer.assertion.file is provided, this configuration will be ignored.

Type:	int
Default:	60
Valid Values:	[0,…,3600]
Importance:	low

sasl.oauthbearer.clock.skew.seconds

The (optional) value in seconds to allow for differences between the time of the OAuth/OIDC identity provider and the broker.

Type:	int
Default:	30
Valid Values:
Importance:	low

sasl.oauthbearer.expected.audience

The (optional) comma-delimited setting for the broker to use to verify that the JWT was issued for one of the expected audiences. The JWT will be inspected for the standard OAuth “aud” claim and if this value is set, the broker will match the value from JWT’s “aud” claim to see if there is an exact match. If there is no match, the broker will reject the JWT and authentication will fail.

Type:	list
Default:	“”
Valid Values:
Importance:	low

sasl.oauthbearer.expected.issuer

The (optional) setting for the broker to use to verify that the JWT was created by the expected issuer. The JWT will be inspected for the standard OAuth “iss” claim and if this value is set, the broker will match it exactly against what is in the JWT’s “iss” claim. If there is no match, the broker will reject the JWT and authentication will fail.

Type:	string
Default:	null
Valid Values:
Importance:	low

sasl.oauthbearer.header.urlencode

The (optional) setting to enable the OAuth client to URL-encode the client_id and client_secret in the authorization header in accordance with RFC6749, see here for more details. The default value is set to ‘false’ for backward compatibility

Type:	boolean
Default:	false
Valid Values:
Importance:	low

sasl.oauthbearer.iat.validation.enabled

Setting this flag true, would mandate the presence of iat (Issued At) claim in the token.However, there is no validation on the value of this field

Type:	boolean
Default:	false
Valid Values:
Importance:	low

sasl.oauthbearer.jti.validation.enabled

Setting this flag true, would mandate the presence of jti (JWT ID) claim in the token.However, there is no validation on the value of this field

Type:	boolean
Default:	false
Valid Values:
Importance:	low

sasl.oauthbearer.jwks.endpoint.refresh.ms

The (optional) value in milliseconds for the broker to wait between refreshing its JWKS (JSON Web Key Set) cache that contains the keys to verify the signature of the JWT.

Type:	long
Default:	3600000 (1 hour)
Valid Values:
Importance:	low

sasl.oauthbearer.jwks.endpoint.retry.backoff.max.ms

The (optional) value in milliseconds for the maximum wait between attempts to retrieve the JWKS (JSON Web Key Set) from the external authentication provider. JWKS retrieval uses an exponential backoff algorithm with an initial wait based on the sasl.oauthbearer.jwks.endpoint.retry.backoff.ms setting and will double in wait length between attempts up to a maximum wait length specified by the sasl.oauthbearer.jwks.endpoint.retry.backoff.max.ms setting.

Type:	long
Default:	10000 (10 seconds)
Valid Values:
Importance:	low

sasl.oauthbearer.jwks.endpoint.retry.backoff.ms

The (optional) value in milliseconds for the initial wait between JWKS (JSON Web Key Set) retrieval attempts from the external authentication provider. JWKS retrieval uses an exponential backoff algorithm with an initial wait based on the sasl.oauthbearer.jwks.endpoint.retry.backoff.ms setting and will double in wait length between attempts up to a maximum wait length specified by the sasl.oauthbearer.jwks.endpoint.retry.backoff.max.ms setting.

Type:	long
Default:	100
Valid Values:
Importance:	low

sasl.oauthbearer.scope.claim.name

The OAuth claim for the scope is often named “scope”, but this (optional) setting can provide a different name to use for the scope included in the JWT payload’s claims if the OAuth/OIDC provider uses a different name for that claim.

Type:	string
Default:	scope
Valid Values:
Importance:	low

sasl.oauthbearer.sub.claim.name

The OAuth claim for the subject is often named “sub”, but this (optional) setting can provide a different name to use for the subject included in the JWT payload’s claims if the OAuth/OIDC provider uses a different name for that claim.

Type:	string
Default:	sub
Valid Values:
Importance:	low

security.providers

A list of configurable creator classes each returning a provider implementing security algorithms. These classes should implement the org.apache.kafka.common.security.auth.SecurityProviderCreator interface.

Type:	string
Default:	null
Valid Values:
Importance:	low

ssl.cipher.suites

A list of cipher suites. This is a named combination of authentication, encryption, MAC and key exchange algorithm used to negotiate the security settings for a network connection using TLS or SSL network protocol. By default all the available cipher suites are supported.

Type:	list
Default:	“”
Valid Values:
Importance:	low

ssl.endpoint.identification.algorithm

The endpoint identification algorithm to validate server hostname using server certificate.

Type:	string
Default:	https
Valid Values:
Importance:	low

ssl.engine.factory.class

The class of type org.apache.kafka.common.security.auth.SslEngineFactory to provide SSLEngine objects. Default value is org.apache.kafka.common.security.ssl.DefaultSslEngineFactory. Alternatively, setting this to org.apache.kafka.common.security.ssl.CommonNameLoggingSslEngineFactory will log the common name of expired SSL certificates used by clients to authenticate at any of the brokers with log level INFO. Note that this will cause a tiny delay during establishment of new connections from mTLS clients to brokers due to the extra code for examining the certificate chain provided by the client. Note further that the implementation uses a custom truststore based on the standard Java truststore and thus might be considered a security risk due to not being as mature as the standard one.

Type:	class
Default:	null
Valid Values:
Importance:	low

ssl.keymanager.algorithm

The algorithm used by key manager factory for SSL connections. Default value is the key manager factory algorithm configured for the Java Virtual Machine.

Type:	string
Default:	SunX509
Valid Values:
Importance:	low

ssl.secure.random.implementation

The SecureRandom PRNG implementation to use for SSL cryptography operations.

Type:	string
Default:	null
Valid Values:
Importance:	low

ssl.trustmanager.algorithm

The algorithm used by trust manager factory for SSL connections. Default value is the trust manager factory algorithm configured for the Java Virtual Machine.

Type:	string
Default:	PKIX
Valid Values:
Importance:	low

transaction.timeout.ms

The maximum amount of time in milliseconds that a transaction will remain open before the coordinator proactively aborts it. The start of the transaction is set at the time that the first partition is added to it. If this value is larger than the transaction.max.timeout.ms setting in the broker, the request will fail with a InvalidTxnTimeoutException error.

Type:	int
Default:	60000 (1 minute)
Valid Values:
Importance:	low

transaction.two.phase.commit.enable

If set to true, then the broker is informed that the client is participating in two phase commit protocol and transactions that this client starts never expire.

Type:	boolean
Default:	false
Valid Values:
Importance:	low

transactional.id

The TransactionalId to use for transactional delivery. This enables reliability semantics which span multiple producer sessions since it allows the client to guarantee that transactions using the same TransactionalId have been completed prior to starting any new transactions. If no TransactionalId is provided, then the producer is limited to idempotent delivery. If a TransactionalId is configured, enable.idempotence is implied. By default the TransactionId is not configured, which means transactions cannot be used. Note that, by default, transactions require a cluster of at least three brokers which is the recommended setting for production; for development you can change this, by adjusting broker setting transaction.state.log.replication.factor.

Type:	string
Default:	null
Valid Values:	non-empty string
Importance:	low

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