Consumer Configs

Tags:

Below is the consumer and share consumer configuration:

key.deserializer
Deserializer class for key that implements the org.apache.kafka.common.serialization.Deserializer interface.
Type: class
Default:
Valid Values:
Importance: high
value.deserializer
Deserializer class for value that implements the org.apache.kafka.common.serialization.Deserializer interface.
Type: class
Default:
Valid Values:
Importance: high
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: non-null string
Importance: high
fetch.min.bytes
The minimum amount of data the server should return for a fetch request. If insufficient data is available the request will wait for that much data to accumulate before answering the request. The default setting of 1 byte means that fetch requests are answered as soon as that many byte(s) of data is available or the fetch request times out waiting for data to arrive. Setting this to a larger value will cause the server to wait for larger amounts of data to accumulate which can improve server throughput a bit at the cost of some additional latency.
Type: int
Default: 1
Valid Values: [0,...]
Importance: high
group.id
A unique string that identifies the consumer group this consumer belongs to. This property is required if the consumer uses either the group management functionality by using subscribe(topic) or the Kafka-based offset management strategy.
Type: string
Default: null
Valid Values:
Importance: high
group.protocol
The group protocol consumer should use. We currently support "classic" or "consumer". If "consumer" is specified, then the consumer group protocol will be used. Otherwise, the classic group protocol will be used.
Type: string
Default: classic
Valid Values: (case insensitive) [CONSUMER, CLASSIC]
Importance: high
heartbeat.interval.ms
The expected time 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. This config is only supported if group.protocol is set to "classic". In that case, 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.If group.protocol is set to "consumer", this config is not supported, as the heartbeat interval is controlled by the broker with group.consumer.heartbeat.interval.ms.
Type: int
Default: 3000 (3 seconds)
Valid Values:
Importance: high
max.partition.fetch.bytes
The maximum amount of data per-partition the server will return. Records are fetched in batches by the consumer. If the first record batch in the first non-empty partition of the fetch is larger than this limit, the batch will still be returned to ensure that the consumer can make progress. The maximum record batch size accepted by the broker is defined via message.max.bytes (broker config) or max.message.bytes (topic config). See fetch.max.bytes for limiting the consumer request size. Consider increasing max.partition.fetch.bytes especially in the cases of remote storage reads (KIP-405), because currently only one partition per fetch request is served from the remote store (KAFKA-14915).
Type: int
Default: 1048576 (1 mebibyte)
Valid Values: [0,...]
Importance: high
session.timeout.ms
The timeout used to detect client failures when using Kafka's group management facility. The client 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 client 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. Note that this client configuration is not supported when group.protocol is set to "consumer". In that case, session timeout is controlled by the broker config group.consumer.session.timeout.ms.
Type: int
Default: 45000 (45 seconds)
Valid Values:
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
allow.auto.create.topics
Allow automatic topic creation on the broker when subscribing to or assigning a topic. A topic being subscribed to will be automatically created only if the broker allows for it using `auto.create.topics.enable` broker configuration.
Type: boolean
Default: true
Valid Values:
Importance: medium
auto.offset.reset
What to do when there is no initial offset in Kafka or if the current offset does not exist any more on the server (e.g. because that data has been deleted):
- earliest: automatically reset the offset to the earliest offset
- latest: automatically reset the offset to the latest offset
- by_duration:<duration>: automatically reset the offset to a configured <duration> from the current timestamp. <duration> must be specified in ISO8601 format (PnDTnHnMn.nS). Negative duration is not allowed.
- none: throw exception to the consumer if no previous offset is found for the consumer's group
- anything else: throw exception to the consumer.
Note that altering partition numbers while setting this config to latest may cause message delivery loss since producers could start to send messages to newly added partitions (i.e. no initial offsets exist yet) before consumers reset their offsets.
Type: string
Default: latest
Valid Values: [latest, earliest, none, by_duration:PnDTnHnMn.nS]
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
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
default.api.timeout.ms
Specifies the timeout (in milliseconds) for client APIs. This configuration is used as the default timeout for all client operations that do not specify a timeout parameter.
Type: int
Default: 60000 (1 minute)
Valid Values: [0,...]
Importance: medium
enable.auto.commit
If true the consumer's offset will be periodically committed in the background.
Type: boolean
Default: true
Valid Values:
Importance: medium
exclude.internal.topics
Whether internal topics matching a subscribed pattern should be excluded from the subscription. It is always possible to explicitly subscribe to an internal topic.
Type: boolean
Default: true
Valid Values:
Importance: medium
fetch.max.bytes
The maximum amount of data the server should return for a fetch request. Records are fetched in batches by the consumer, and if the first record batch in the first non-empty partition of the fetch is larger than this value, the record batch will still be returned to ensure that the consumer can make progress. As such, this is not a absolute maximum. The maximum record batch size accepted by the broker is defined via message.max.bytes (broker config) or max.message.bytes (topic config). A fetch request consists of many partitions, and there is another setting that controls how much data is returned for each partition in a fetch request - see max.partition.fetch.bytes. Note that there is a current limitation when performing remote reads from tiered storage (KIP-405) - only one partition out of the fetch request is fetched from the remote store (KAFKA-14915). Note also that the consumer performs multiple fetches in parallel.
Type: int
Default: 52428800 (50 mebibytes)
Valid Values: [0,...]
Importance: medium
group.instance.id
A unique identifier of the consumer instance provided by the end user. Only non-empty strings are permitted. If set, the consumer is treated as a static member, which means that only one instance with this ID is allowed in the consumer group at any time. This can be used in combination with a larger session timeout to avoid group rebalances caused by transient unavailability (e.g. process restarts). If not set, the consumer will join the group as a dynamic member, which is the traditional behavior.
Type: string
Default: null
Valid Values: non-empty string
Importance: medium
group.remote.assignor
The name of the server-side assignor to use. If not specified, the group coordinator will pick the first assignor defined in the broker config group.consumer.assignors.This configuration is applied only if group.protocol is set to "consumer".
Type: string
Default: null
Valid Values:
Importance: medium
isolation.level
Controls how to read messages written transactionally. If set to read_committed, consumer.poll() will only return transactional messages which have been committed. If set to read_uncommitted (the default), consumer.poll() will return all messages, even transactional messages which have been aborted. Non-transactional messages will be returned unconditionally in either mode.
Messages will always be returned in offset order. Hence, in read_committed mode, consumer.poll() will only return messages up to the last stable offset (LSO), which is the one less than the offset of the first open transaction. In particular any messages appearing after messages belonging to ongoing transactions will be withheld until the relevant transaction has been completed. As a result, read_committed consumers will not be able to read up to the high watermark when there are in flight transactions.
Further, when in read_committed the seekToEnd method will return the LSO
Type: string
Default: read_uncommitted
Valid Values: [read_committed, read_uncommitted]
Importance: medium
max.poll.interval.ms
The maximum delay between invocations of 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. For consumers using a non-null group.instance.id which reach this timeout, partitions will not be immediately reassigned. Instead, the consumer will stop sending heartbeats and partitions will be reassigned after expiration of the session timeout (defined by the client config session.timeout.ms if using the Classic rebalance protocol, or by the broker config group.consumer.session.timeout.ms if using the Consumer protocol). This mirrors the behavior of a static consumer which has shutdown.
Type: int
Default: 300000 (5 minutes)
Valid Values: [1,...]
Importance: medium
max.poll.records
The maximum number of records returned in a single call to poll(). Note, that max.poll.records does not impact the underlying fetching behavior. The consumer will cache the records from each fetch request and returns them incrementally from each poll.
Type: int
Default: 500
Valid Values: [1,...]
Importance: medium
partition.assignment.strategy
A list of class names or class types, ordered by preference, of supported partition assignment strategies that the client will use to distribute partition ownership amongst consumer instances when group management is used. Available options are:
- org.apache.kafka.clients.consumer.RangeAssignor: Assigns partitions on a per-topic basis.
- org.apache.kafka.clients.consumer.RoundRobinAssignor: Assigns partitions to consumers in a round-robin fashion.
- org.apache.kafka.clients.consumer.StickyAssignor: Guarantees an assignment that is maximally balanced while preserving as many existing partition assignments as possible.
- org.apache.kafka.clients.consumer.CooperativeStickyAssignor: Follows the same StickyAssignor logic, but allows for cooperative rebalancing.
The default assignor is [RangeAssignor, CooperativeStickyAssignor], which will use the RangeAssignor by default, but allows upgrading to the CooperativeStickyAssignor with just a single rolling bounce that removes the RangeAssignor from the list.
Implementing the org.apache.kafka.clients.consumer.ConsumerPartitionAssignor interface allows you to plug in a custom assignment strategy.
Type: list
Default: class org.apache.kafka.clients.consumer.RangeAssignor,class org.apache.kafka.clients.consumer.CooperativeStickyAssignor
Valid Values: non-null string
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: 65536 (64 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.
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.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:
1. The header section is a base 64-encoded JWT header that contains values like alg (Algorithm), typ (Type, always the literal value JWT), etc.
2. The payload section includes the base 64-encoded set of JWT claims, such as aud (Audience), iss (Issuer), sub (Subject), etc.
3. The signature section is the concatenated header and payload sections that was signed using a private key
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:
- sasl.oauthbearer.client.credentials.client.id from configuration
- clientId from JAAS
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:
- sasl.oauthbearer.client.credentials.client.secret from configuration
- clientSecret from JAAS
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:
- org.apache.kafka.common.security.oauthbearer.ClientCredentialsJwtRetriever
- org.apache.kafka.common.security.oauthbearer.DefaultJwtRetriever
- org.apache.kafka.common.security.oauthbearer.FileJwtRetriever
- org.apache.kafka.common.security.oauthbearer.JwtBearerJwtRetriever
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:
- org.apache.kafka.common.security.oauthbearer.BrokerJwtValidator
- org.apache.kafka.common.security.oauthbearer.ClientJwtValidator
- org.apache.kafka.common.security.oauthbearer.DefaultJwtValidator
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:
- sasl.oauthbearer.scope from configuration
- scope from JAAS
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
share.acknowledgement.mode
Controls the acknowledgement mode for a share consumer. If set to implicit, the acknowledgement mode of the consumer is implicit and it must not use org.apache.kafka.clients.consumer.ShareConsumer.acknowledge() to acknowledge delivery of records. Instead, delivery is acknowledged implicitly on the next call to poll or commit. If set to explicit, the acknowledgement mode of the consumer is explicit and it must use org.apache.kafka.clients.consumer.ShareConsumer.acknowledge() to acknowledge delivery of records.
Type: string
Default: implicit
Valid Values: [implicit, explicit]
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. 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
auto.commit.interval.ms
The frequency in milliseconds that the consumer offsets are auto-committed to Kafka if enable.auto.commit is set to true.
Type: int
Default: 5000 (5 seconds)
Valid Values: [0,...]
Importance: low
check.crcs
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.
Type: boolean
Default: true
Valid Values:
Importance: low
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: low
client.rack
A rack identifier for this client. This can be any string value which indicates where this client is physically located. It corresponds with the broker config 'broker.rack'
Type: string
Default: ""
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
fetch.max.wait.ms
The maximum amount of time the server will block before answering the fetch request there isn't sufficient data to immediately satisfy the requirement given by fetch.min.bytes. This config is used only for local log fetch. To tune the remote fetch maximum wait time, please refer to 'remote.fetch.max.wait.ms' broker config
Type: int
Default: 500
Valid Values: [0,...]
Importance: low
interceptor.classes
A list of classes to use as interceptors. Implementing the org.apache.kafka.clients.consumer.ConsumerInterceptor interface allows you to intercept (and possibly mutate) records received by the consumer. By default, there are no interceptors.
Type: list
Default: ""
Valid Values: non-null string
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.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: non-null string
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
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.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:

  x = the current timestamp in seconds, on client
  y = the value of this configuration

Then:

  exp = x + y
```
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.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:

  x = the current timestamp in seconds, on client
  y = the value of this configuration

Then:

  nbf = x - y
```
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: null
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.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: null
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

Type:	class
Default:
Valid Values:
Importance:	high

Type:	class
Default:
Valid Values:
Importance:	high

Type:	list
Default:	""
Valid Values:	non-null string
Importance:	high

Type:	int
Default:	1
Valid Values:	[0,...]
Importance:	high

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

Type:	string
Default:	classic
Valid Values:	(case insensitive) [CONSUMER, CLASSIC]
Importance:	high

Type:	int
Default:	3000 (3 seconds)
Valid Values:
Importance:	high

Type:	int
Default:	1048576 (1 mebibyte)
Valid Values:	[0,...]
Importance:	high

Type:	int
Default:	45000 (45 seconds)
Valid Values:
Importance:	high

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

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

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

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

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

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

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

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

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

Type:	string
Default:	latest
Valid Values:	[latest, earliest, none, by_duration:PnDTnHnMn.nS]
Importance:	medium

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

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

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

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

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

Type:	int
Default:	52428800 (50 mebibytes)
Valid Values:	[0,...]
Importance:	medium

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

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

Type:	string
Default:	read_uncommitted
Valid Values:	[read_committed, read_uncommitted]
Importance:	medium

Type:	int
Default:	300000 (5 minutes)
Valid Values:	[1,...]
Importance:	medium

Type:	int
Default:	500
Valid Values:	[1,...]
Importance:	medium

Type:	list
Default:	class org.apache.kafka.clients.consumer.RangeAssignor,class org.apache.kafka.clients.consumer.CooperativeStickyAssignor
Valid Values:	non-null string
Importance:	medium

Type:	int
Default:	65536 (64 kibibytes)
Valid Values:	[-1,...]
Importance:	medium

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Last modified November 7, 2025: Multiple updates and site refresh (#739) (8c3540c99)

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

Type:	int
Default:	5000 (5 seconds)
Valid Values:	[0,...]
Importance:	low

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

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