Chapter 5. Kafka Connect configuration properties


config.storage.topic

Type: string
Importance: high

The name of the Kafka topic where connector configurations are stored.

group.id

Type: string
Importance: high

A unique string that identifies the Connect cluster group this worker belongs to.

key.converter

Type: class
Importance: high

Converter class used to convert between Kafka Connect format and the serialized form that is written to Kafka. This controls the format of the keys in messages written to or read from Kafka, and since this is independent of connectors it allows any connector to work with any serialization format. Examples of common formats include JSON and Avro.

offset.storage.topic

Type: string
Importance: high

The name of the Kafka topic where source connector offsets are stored.

status.storage.topic

Type: string
Importance: high

The name of the Kafka topic where connector and task status are stored.

value.converter

Type: class
Importance: high

Converter class used to convert between Kafka Connect format and the serialized form that is written to Kafka. This controls the format of the values in messages written to or read from Kafka, and since this is independent of connectors it allows any connector to work with any serialization format. Examples of common formats include JSON and Avro.

bootstrap.servers

Type: list
Default: localhost:9092
Importance: high

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,…​.

exactly.once.source.support

Type: string
Default: disabled
Valid Values: (case insensitive) [DISABLED, ENABLED, PREPARING]
Importance: high

Whether to enable exactly-once support for source connectors in the cluster by using transactions to write source records and their source offsets, and by proactively fencing out old task generations before bringing up new ones. To enable exactly-once source support on a new cluster, set this property to 'enabled'. To enable support on an existing cluster, first set to 'preparing' on every worker in the cluster, then set to 'enabled'. A rolling upgrade may be used for both changes. For more information on this feature, see the exactly-once source support documentation.

heartbeat.interval.ms

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

The expected time between heartbeats to the group coordinator when using Kafka’s group management facilities. Heartbeats are used to ensure that the worker’s session stays active and to facilitate rebalancing when new members join or leave the group. The value must be set lower than session.timeout.ms, but typically should be set no higher than 1/3 of that value. It can be adjusted even lower to control the expected time for normal rebalances.

rebalance.timeout.ms

Type: int
Default: 60000 (1 minute)
Importance: high

The maximum allowed time for each worker to join the group once a rebalance has begun. This is basically a limit on the amount of time needed for all tasks to flush any pending data and commit offsets. If the timeout is exceeded, then the worker will be removed from the group, which will cause offset commit failures.

session.timeout.ms

Type: int
Default: 10000 (10 seconds)
Importance: high

The timeout used to detect worker failures. The worker 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 the worker 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.

ssl.key.password

Type: password
Default: null
Importance: high

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

ssl.keystore.certificate.chain

Type: password
Default: null
Importance: high

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.

ssl.keystore.key

Type: password
Default: null
Importance: high

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'.

ssl.keystore.location

Type: string
Default: null
Importance: high

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

ssl.keystore.password

Type: password
Default: null
Importance: high

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.

ssl.truststore.certificates

Type: password
Default: null
Importance: high

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

ssl.truststore.location

Type: string
Default: null
Importance: high

The location of the trust store file.

ssl.truststore.password

Type: password
Default: null
Importance: high

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.

client.dns.lookup

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

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.

connections.max.idle.ms

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

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

connector.client.config.override.policy

Type: string
Default: All
Importance: medium

Class name or alias of implementation of ConnectorClientConfigOverridePolicy. Defines what client configurations can be overridden by the connector. The default implementation is All, meaning connector configurations can override all client properties. The other possible policies in the framework include None to disallow connectors from overriding client properties, and Principal to allow connectors to override only client principals.

receive.buffer.bytes

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

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.

request.timeout.ms

Type: int
Default: 40000 (40 seconds)
Valid Values: [0,…​]
Importance: medium

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.

sasl.client.callback.handler.class

Type: class
Default: null
Importance: medium

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

sasl.jaas.config

Type: password
Default: null
Importance: medium

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;.

sasl.kerberos.service.name

Type: string
Default: null
Importance: medium

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

sasl.login.callback.handler.class

Type: class
Default: null
Importance: medium

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.

sasl.login.class

Type: class
Default: null
Importance: medium

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.

sasl.mechanism

Type: string
Default: GSSAPI
Importance: medium

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

sasl.oauthbearer.jwks.endpoint.url

Type: string
Default: null
Importance: medium

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.

sasl.oauthbearer.token.endpoint.url

Type: string
Default: null
Importance: medium

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.jaas.config. 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.

security.protocol

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

Protocol used to communicate with brokers.

send.buffer.bytes

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

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.

ssl.enabled.protocols

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

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.

ssl.keystore.type

Type: string
Default: JKS
Importance: medium

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].

ssl.protocol

Type: string
Default: TLSv1.3
Importance: medium

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'.

ssl.provider

Type: string
Default: null
Importance: medium

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

ssl.truststore.type

Type: string
Default: JKS
Importance: medium

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

worker.sync.timeout.ms

Type: int
Default: 3000 (3 seconds)
Importance: medium

When the worker is out of sync with other workers and needs to resynchronize configurations, wait up to this amount of time before giving up, leaving the group, and waiting a backoff period before rejoining.

worker.unsync.backoff.ms

Type: int
Default: 300000 (5 minutes)
Importance: medium

When the worker is out of sync with other workers and fails to catch up within worker.sync.timeout.ms, leave the Connect cluster for this long before rejoining.

access.control.allow.methods

Type: string
Default: ""
Importance: low

Sets the methods supported for cross origin requests by setting the Access-Control-Allow-Methods header. The default value of the Access-Control-Allow-Methods header allows cross origin requests for GET, POST and HEAD.

access.control.allow.origin

Type: string
Default: ""
Importance: low

Value to set the Access-Control-Allow-Origin header to for REST API requests.To enable cross origin access, set this to the domain of the application that should be permitted to access the API, or '*' to allow access from any domain. The default value only allows access from the domain of the REST API.

admin.listeners

Type: list
Default: null
Valid Values: List of comma-separated URLs, ex: http://localhost:8080,https://localhost:8443.
Importance: low

List of comma-separated URIs the Admin REST API will listen on. The supported protocols are HTTP and HTTPS. An empty or blank string will disable this feature. The default behavior is to use the regular listener (specified by the 'listeners' property).

client.id

Type: string
Default: ""
Importance: low

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.

config.providers

Type: list
Default: ""
Importance: low

Comma-separated names of ConfigProvider classes, loaded and used in the order specified. Implementing the interface ConfigProvider allows you to replace variable references in connector configurations, such as for externalized secrets.

config.storage.replication.factor

Type: short
Default: 3
Valid Values: Positive number not larger than the number of brokers in the Kafka cluster, or -1 to use the broker’s default
Importance: low

Replication factor used when creating the configuration storage topic.

connect.protocol

Type: string
Default: sessioned
Valid Values: [eager, compatible, sessioned]
Importance: low

Compatibility mode for Kafka Connect Protocol.

header.converter

Type: class
Default: org.apache.kafka.connect.storage.SimpleHeaderConverter
Importance: low

HeaderConverter class used to convert between Kafka Connect format and the serialized form that is written to Kafka. This controls the format of the header values in messages written to or read from Kafka, and since this is independent of connectors it allows any connector to work with any serialization format. Examples of common formats include JSON and Avro. By default, the SimpleHeaderConverter is used to serialize header values to strings and deserialize them by inferring the schemas.

inter.worker.key.generation.algorithm

Type: string
Default: HmacSHA256
Valid Values: Any KeyGenerator algorithm supported by the worker JVM
Importance: low

The algorithm to use for generating internal request keys. The algorithm 'HmacSHA256' will be used as a default on JVMs that support it; on other JVMs, no default is used and a value for this property must be manually specified in the worker config.

inter.worker.key.size

Type: int
Default: null
Importance: low

The size of the key to use for signing internal requests, in bits. If null, the default key size for the key generation algorithm will be used.

inter.worker.key.ttl.ms

Type: int
Default: 3600000 (1 hour)
Valid Values: [0,…​,2147483647]
Importance: low

The TTL of generated session keys used for internal request validation (in milliseconds).

inter.worker.signature.algorithm

Type: string
Default: HmacSHA256
Valid Values: Any MAC algorithm supported by the worker JVM
Importance: low

The algorithm used to sign internal requestsThe algorithm 'inter.worker.signature.algorithm' will be used as a default on JVMs that support it; on other JVMs, no default is used and a value for this property must be manually specified in the worker config.

inter.worker.verification.algorithms

Type: list
Default: HmacSHA256
Valid Values: A list of one or more MAC algorithms, each supported by the worker JVM
Importance: low

A list of permitted algorithms for verifying internal requests, which must include the algorithm used for the inter.worker.signature.algorithm property. The algorithm(s) '[HmacSHA256]' will be used as a default on JVMs that provide them; on other JVMs, no default is used and a value for this property must be manually specified in the worker config.

listeners

Type: list
Default: http://:8083
Valid Values: List of comma-separated URLs, ex: http://localhost:8080,https://localhost:8443.
Importance: low

List of comma-separated URIs the REST API will listen on. The supported protocols are HTTP and HTTPS. Specify hostname as 0.0.0.0 to bind to all interfaces. Leave hostname empty to bind to default interface. Examples of legal listener lists: HTTP://myhost:8083,HTTPS://myhost:8084.

metadata.max.age.ms

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

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.

metadata.recovery.rebootstrap.trigger.ms

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

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.

metadata.recovery.strategy

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

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.

metric.reporters

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

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.

metrics.num.samples

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

The number of samples maintained to compute metrics.

metrics.recording.level

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

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.

metrics.sample.window.ms

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

The window of time a metrics sample is computed over.

offset.flush.interval.ms

Type: long
Default: 60000 (1 minute)
Importance: low

Interval at which to try committing offsets for tasks.

offset.flush.timeout.ms

Type: long
Default: 5000 (5 seconds)
Importance: low

Maximum number of milliseconds to wait for records to flush and partition offset data to be committed to offset storage before cancelling the process and restoring the offset data to be committed in a future attempt. This property has no effect for source connectors running with exactly-once support.

offset.storage.partitions

Type: int
Default: 25
Valid Values: Positive number, or -1 to use the broker’s default
Importance: low

The number of partitions used when creating the offset storage topic.

offset.storage.replication.factor

Type: short
Default: 3
Valid Values: Positive number not larger than the number of brokers in the Kafka cluster, or -1 to use the broker’s default
Importance: low

Replication factor used when creating the offset storage topic.

plugin.discovery

Type: string
Default: hybrid_warn
Valid Values: (case insensitive) [ONLY_SCAN, SERVICE_LOAD, HYBRID_WARN, HYBRID_FAIL]
Importance: low

Method to use to discover plugins present in the classpath and plugin.path configuration. This can be one of multiple values with the following meanings: * only_scan: Discover plugins only by reflection. Plugins which are not discoverable by ServiceLoader will not impact worker startup. * hybrid_warn: Discover plugins reflectively and by ServiceLoader. Plugins which are not discoverable by ServiceLoader will print warnings during worker startup. * hybrid_fail: Discover plugins reflectively and by ServiceLoader. Plugins which are not discoverable by ServiceLoader will cause worker startup to fail. * service_load: Discover plugins only by ServiceLoader. Faster startup than other modes. Plugins which are not discoverable by ServiceLoader may not be usable.

plugin.path

Type: list
Default: null
Importance: low

List of paths separated by commas (,) that contain plugins (connectors, converters, transformations). The list should consist of top level directories that include any combination of: a) directories immediately containing jars with plugins and their dependencies b) uber-jars with plugins and their dependencies c) directories immediately containing the package directory structure of classes of plugins and their dependencies Note: symlinks will be followed to discover dependencies or plugins. Examples: plugin.path=/usr/local/share/java,/usr/local/share/kafka/plugins,/opt/connectors Do not use config provider variables in this property, since the raw path is used by the worker’s scanner before config providers are initialized and used to replace variables.

reconnect.backoff.max.ms

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

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.

reconnect.backoff.ms

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

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.

response.http.headers.config

Type: string
Default: ""
Valid Values: Comma-separated header rules, where each header rule is of the form '[action] [header name]:[header value]' and optionally surrounded by double quotes if any part of a header rule contains a comma
Importance: low

Rules for REST API HTTP response headers.

rest.advertised.host.name

Type: string
Default: null
Importance: low

If this is set, this is the hostname that will be given out to other workers to connect to.

rest.advertised.listener

Type: string
Default: null
Importance: low

Sets the advertised listener (HTTP or HTTPS) which will be given to other workers to use.

rest.advertised.port

Type: int
Default: null
Importance: low

If this is set, this is the port that will be given out to other workers to connect to.

rest.extension.classes

Type: list
Default: ""
Importance: low

Comma-separated names of ConnectRestExtension classes, loaded and called in the order specified. Implementing the interface ConnectRestExtension allows you to inject into Connect’s REST API user defined resources like filters. Typically used to add custom capability like logging, security, etc.

retry.backoff.max.ms

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

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.

retry.backoff.ms

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

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.

sasl.kerberos.kinit.cmd

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

Kerberos kinit command path.

sasl.kerberos.min.time.before.relogin

Type: long
Default: 60000
Importance: low

Login thread sleep time between refresh attempts.

sasl.kerberos.ticket.renew.jitter

Type: double
Default: 0.05
Importance: low

Percentage of random jitter added to the renewal time.

sasl.kerberos.ticket.renew.window.factor

Type: double
Default: 0.8
Importance: low

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.

sasl.login.connect.timeout.ms

Type: int
Default: null
Importance: low

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

sasl.login.read.timeout.ms

Type: int
Default: null
Importance: low

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

sasl.login.refresh.buffer.seconds

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

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.

sasl.login.refresh.min.period.seconds

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

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.

sasl.login.refresh.window.factor

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

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.

sasl.login.refresh.window.jitter

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

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.

sasl.login.retry.backoff.max.ms

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

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.

sasl.login.retry.backoff.ms

Type: long
Default: 100
Importance: low

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.

sasl.oauthbearer.clock.skew.seconds

Type: int
Default: 30
Importance: low

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

sasl.oauthbearer.expected.audience

Type: list
Default: null
Importance: low

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.

sasl.oauthbearer.expected.issuer

Type: string
Default: null
Importance: low

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.

sasl.oauthbearer.header.urlencode

Type: boolean
Default: false
Importance: low

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.

sasl.oauthbearer.jwks.endpoint.refresh.ms

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

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.

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

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

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.

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

Type: long
Default: 100
Importance: low

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.

sasl.oauthbearer.scope.claim.name

Type: string
Default: scope
Importance: low

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.

sasl.oauthbearer.sub.claim.name

Type: string
Default: sub
Importance: low

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.

scheduled.rebalance.max.delay.ms

Type: int
Default: 300000 (5 minutes)
Valid Values: [0,…​,2147483647]
Importance: low

The maximum delay that is scheduled in order to wait for the return of one or more departed workers before rebalancing and reassigning their connectors and tasks to the group. During this period the connectors and tasks of the departed workers remain unassigned.

socket.connection.setup.timeout.max.ms

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

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.

socket.connection.setup.timeout.ms

Type: long
Default: 10000 (10 seconds)
Valid Values: [0,…​]
Importance: low

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.

ssl.cipher.suites

Type: list
Default: null
Importance: low

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.

ssl.client.auth

Type: string
Default: none
Valid Values: [required, requested, none]
Importance: low

Configures kafka broker to request client authentication. The following settings are common:

  • ssl.client.auth=required If set to required client authentication is required.
  • ssl.client.auth=requested This means client authentication is optional. unlike required, if this option is set client can choose not to provide authentication information about itself
  • ssl.client.auth=none This means client authentication is not needed.
ssl.endpoint.identification.algorithm

Type: string
Default: https
Importance: low

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

ssl.engine.factory.class

Type: class
Default: null
Importance: low

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.

ssl.keymanager.algorithm

Type: string
Default: SunX509
Importance: low

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

ssl.secure.random.implementation

Type: string
Default: null
Importance: low

The SecureRandom PRNG implementation to use for SSL cryptography operations.

ssl.trustmanager.algorithm

Type: string
Default: PKIX
Importance: low

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

status.storage.partitions

Type: int
Default: 5
Valid Values: Positive number, or -1 to use the broker’s default
Importance: low

The number of partitions used when creating the status storage topic.

status.storage.replication.factor

Type: short
Default: 3
Valid Values: Positive number not larger than the number of brokers in the Kafka cluster, or -1 to use the broker’s default
Importance: low

Replication factor used when creating the status storage topic.

task.shutdown.graceful.timeout.ms

Type: long
Default: 5000 (5 seconds)
Importance: low

Amount of time to wait for tasks to shutdown gracefully. This is the total amount of time, not per task. All task have shutdown triggered, then they are waited on sequentially.

topic.creation.enable

Type: boolean
Default: true
Importance: low

Whether to allow automatic creation of topics used by source connectors, when source connectors are configured with topic.creation. properties. Each task will use an admin client to create its topics and will not depend on the Kafka brokers to create topics automatically.

topic.tracking.allow.reset

Type: boolean
Default: true
Importance: low

If set to true, it allows user requests to reset the set of active topics per connector.

topic.tracking.enable

Type: boolean
Default: true
Importance: low

Enable tracking the set of active topics per connector during runtime.

5.1. Source Connector configuration properties

name

Type: string
Valid Values: non-empty string without ISO control characters
Importance: high

Globally unique name to use for this connector.

connector.class

Type: string
Importance: high

Name or alias of the class for this connector. Must be a subclass of org.apache.kafka.connect.connector.Connector. If the connector is org.apache.kafka.connect.file.FileStreamSinkConnector, you can either specify this full name, or use "FileStreamSink" or "FileStreamSinkConnector" to make the configuration a bit shorter.

tasks.max

Type: int
Default: 1
Valid Values: [1,…​]
Importance: high

Maximum number of tasks to use for this connector.

tasks.max.enforce

Type: boolean
Default: true
Importance: low

(Deprecated) Whether to enforce that the tasks.max property is respected by the connector. By default, connectors that generate too many tasks will fail, and existing sets of tasks that exceed the tasks.max property will also be failed. If this property is set to false, then connectors will be allowed to generate more than the maximum number of tasks, and existing sets of tasks that exceed the tasks.max property will be allowed to run. This property is deprecated and will be removed in an upcoming major release.

key.converter

Type: class
Default: null
Valid Values: A concrete subclass of org.apache.kafka.connect.storage.Converter, A class with a public, no-argument constructor
Importance: low

Converter class used to convert between Kafka Connect format and the serialized form that is written to Kafka. This controls the format of the keys in messages written to or read from Kafka, and since this is independent of connectors it allows any connector to work with any serialization format. Examples of common formats include JSON and Avro.

value.converter

Type: class
Default: null
Valid Values: A concrete subclass of org.apache.kafka.connect.storage.Converter, A class with a public, no-argument constructor
Importance: low

Converter class used to convert between Kafka Connect format and the serialized form that is written to Kafka. This controls the format of the values in messages written to or read from Kafka, and since this is independent of connectors it allows any connector to work with any serialization format. Examples of common formats include JSON and Avro.

header.converter

Type: class
Default: null
Valid Values: A concrete subclass of org.apache.kafka.connect.storage.HeaderConverter, A class with a public, no-argument constructor
Importance: low

HeaderConverter class used to convert between Kafka Connect format and the serialized form that is written to Kafka. This controls the format of the header values in messages written to or read from Kafka, and since this is independent of connectors it allows any connector to work with any serialization format. Examples of common formats include JSON and Avro. By default, the SimpleHeaderConverter is used to serialize header values to strings and deserialize them by inferring the schemas.

config.action.reload

Type: string
Default: restart
Valid Values: [none, restart]
Importance: low

The action that Connect should take on the connector when changes in external configuration providers result in a change in the connector’s configuration properties. A value of 'none' indicates that Connect will do nothing. A value of 'restart' indicates that Connect should restart/reload the connector with the updated configuration properties.The restart may actually be scheduled in the future if the external configuration provider indicates that a configuration value will expire in the future.

transforms

Type: list
Default: ""
Valid Values: non-null string, unique transformation aliases
Importance: low

Aliases for the transformations to be applied to records.

predicates

Type: list
Default: ""
Valid Values: non-null string, unique predicate aliases
Importance: low

Aliases for the predicates used by transformations.

errors.retry.timeout

Type: long
Default: 0
Importance: medium

The maximum duration in milliseconds that a failed operation will be reattempted. The default is 0, which means no retries will be attempted. Use -1 for infinite retries.

errors.retry.delay.max.ms

Type: long
Default: 60000 (1 minute)
Importance: medium

The maximum duration in milliseconds between consecutive retry attempts. Jitter will be added to the delay once this limit is reached to prevent thundering herd issues.

errors.tolerance

Type: string
Default: none
Valid Values: [none, all]
Importance: medium

Behavior for tolerating errors during connector operation. 'none' is the default value and signals that any error will result in an immediate connector task failure; 'all' changes the behavior to skip over problematic records.

errors.log.enable

Type: boolean
Default: false
Importance: medium

If true, write each error and the details of the failed operation and problematic record to the Connect application log. This is 'false' by default, so that only errors that are not tolerated are reported.

errors.log.include.messages

Type: boolean
Default: false
Importance: medium

Whether to include in the log the Connect record that resulted in a failure. For sink records, the topic, partition, offset, and timestamp will be logged. For source records, the key and value (and their schemas), all headers, and the timestamp, Kafka topic, Kafka partition, source partition, and source offset will be logged. This is 'false' by default, which will prevent record keys, values, and headers from being written to log files.

topic.creation.groups

Type: list
Default: ""
Valid Values: non-null string, unique topic creation groups
Importance: low

Groups of configurations for topics created by source connectors.

exactly.once.support

Type: string
Default: requested
Valid Values: (case insensitive) [REQUIRED, REQUESTED]
Importance: medium

Permitted values are requested, required. If set to "required", forces a preflight check for the connector to ensure that it can provide exactly-once semantics with the given configuration. Some connectors may be capable of providing exactly-once semantics but not signal to Connect that they support this; in that case, documentation for the connector should be consulted carefully before creating it, and the value for this property should be set to "requested". Additionally, if the value is set to "required" but the worker that performs preflight validation does not have exactly-once support enabled for source connectors, requests to create or validate the connector will fail.

transaction.boundary

Type: string
Default: poll
Valid Values: (case insensitive) [INTERVAL, POLL, CONNECTOR]
Importance: medium

Permitted values are: poll, interval, connector. If set to 'poll', a new producer transaction will be started and committed for every batch of records that each task from this connector provides to Connect. If set to 'connector', relies on connector-defined transaction boundaries; note that not all connectors are capable of defining their own transaction boundaries, and in that case, attempts to instantiate a connector with this value will fail. Finally, if set to 'interval', commits transactions only after a user-defined time interval has passed.

transaction.boundary.interval.ms

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

If 'transaction.boundary' is set to 'interval', determines the interval for producer transaction commits by connector tasks. If unset, defaults to the value of the worker-level 'offset.flush.interval.ms' property. It has no effect if a different transaction.boundary is specified.

offsets.storage.topic

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

The name of a separate offsets topic to use for this connector. If empty or not specified, the worker’s global offsets topic name will be used. If specified, the offsets topic will be created if it does not already exist on the Kafka cluster targeted by this connector (which may be different from the one used for the worker’s global offsets topic if the bootstrap.servers property of the connector’s producer has been overridden from the worker’s). Only applicable in distributed mode; in standalone mode, setting this property will have no effect.

5.2. Sink Connector configuration properties

name

Type: string
Valid Values: non-empty string without ISO control characters
Importance: high

Globally unique name to use for this connector.

connector.class

Type: string
Importance: high

Name or alias of the class for this connector. Must be a subclass of org.apache.kafka.connect.connector.Connector. If the connector is org.apache.kafka.connect.file.FileStreamSinkConnector, you can either specify this full name, or use "FileStreamSink" or "FileStreamSinkConnector" to make the configuration a bit shorter.

tasks.max

Type: int
Default: 1
Valid Values: [1,…​]
Importance: high

Maximum number of tasks to use for this connector.

topics

Type: list
Default: ""
Importance: high

List of topics to consume, separated by commas.

topics.regex

Type: string
Default: ""
Valid Values: valid regex
Importance: high

Regular expression giving topics to consume. Under the hood, the regex is compiled to a java.util.regex.Pattern. Only one of topics or topics.regex should be specified.

tasks.max.enforce

Type: boolean
Default: true
Importance: low

(Deprecated) Whether to enforce that the tasks.max property is respected by the connector. By default, connectors that generate too many tasks will fail, and existing sets of tasks that exceed the tasks.max property will also be failed. If this property is set to false, then connectors will be allowed to generate more than the maximum number of tasks, and existing sets of tasks that exceed the tasks.max property will be allowed to run. This property is deprecated and will be removed in an upcoming major release.

key.converter

Type: class
Default: null
Valid Values: A concrete subclass of org.apache.kafka.connect.storage.Converter, A class with a public, no-argument constructor
Importance: low

Converter class used to convert between Kafka Connect format and the serialized form that is written to Kafka. This controls the format of the keys in messages written to or read from Kafka, and since this is independent of connectors it allows any connector to work with any serialization format. Examples of common formats include JSON and Avro.

value.converter

Type: class
Default: null
Valid Values: A concrete subclass of org.apache.kafka.connect.storage.Converter, A class with a public, no-argument constructor
Importance: low

Converter class used to convert between Kafka Connect format and the serialized form that is written to Kafka. This controls the format of the values in messages written to or read from Kafka, and since this is independent of connectors it allows any connector to work with any serialization format. Examples of common formats include JSON and Avro.

header.converter

Type: class
Default: null
Valid Values: A concrete subclass of org.apache.kafka.connect.storage.HeaderConverter, A class with a public, no-argument constructor
Importance: low

HeaderConverter class used to convert between Kafka Connect format and the serialized form that is written to Kafka. This controls the format of the header values in messages written to or read from Kafka, and since this is independent of connectors it allows any connector to work with any serialization format. Examples of common formats include JSON and Avro. By default, the SimpleHeaderConverter is used to serialize header values to strings and deserialize them by inferring the schemas.

config.action.reload

Type: string
Default: restart
Valid Values: [none, restart]
Importance: low

The action that Connect should take on the connector when changes in external configuration providers result in a change in the connector’s configuration properties. A value of 'none' indicates that Connect will do nothing. A value of 'restart' indicates that Connect should restart/reload the connector with the updated configuration properties.The restart may actually be scheduled in the future if the external configuration provider indicates that a configuration value will expire in the future.

transforms

Type: list
Default: ""
Valid Values: non-null string, unique transformation aliases
Importance: low

Aliases for the transformations to be applied to records.

predicates

Type: list
Default: ""
Valid Values: non-null string, unique predicate aliases
Importance: low

Aliases for the predicates used by transformations.

errors.retry.timeout

Type: long
Default: 0
Importance: medium

The maximum duration in milliseconds that a failed operation will be reattempted. The default is 0, which means no retries will be attempted. Use -1 for infinite retries.

errors.retry.delay.max.ms

Type: long
Default: 60000 (1 minute)
Importance: medium

The maximum duration in milliseconds between consecutive retry attempts. Jitter will be added to the delay once this limit is reached to prevent thundering herd issues.

errors.tolerance

Type: string
Default: none
Valid Values: [none, all]
Importance: medium

Behavior for tolerating errors during connector operation. 'none' is the default value and signals that any error will result in an immediate connector task failure; 'all' changes the behavior to skip over problematic records.

errors.log.enable

Type: boolean
Default: false
Importance: medium

If true, write each error and the details of the failed operation and problematic record to the Connect application log. This is 'false' by default, so that only errors that are not tolerated are reported.

errors.log.include.messages

Type: boolean
Default: false
Importance: medium

Whether to include in the log the Connect record that resulted in a failure. For sink records, the topic, partition, offset, and timestamp will be logged. For source records, the key and value (and their schemas), all headers, and the timestamp, Kafka topic, Kafka partition, source partition, and source offset will be logged. This is 'false' by default, which will prevent record keys, values, and headers from being written to log files.

errors.deadletterqueue.topic.name

Type: string
Default: ""
Importance: medium

The name of the topic to be used as the dead letter queue (DLQ) for messages that result in an error when processed by this sink connector, or its transformations or converters. The topic name is blank by default, which means that no messages are to be recorded in the DLQ.

errors.deadletterqueue.topic.replication.factor

Type: short
Default: 3
Importance: medium

Replication factor used to create the dead letter queue topic when it doesn’t already exist.

errors.deadletterqueue.context.headers.enable

Type: boolean
Default: false
Importance: medium

If true, add headers containing error context to the messages written to the dead letter queue. To avoid clashing with headers from the original record, all error context header keys, all error context header keys will start with __connect.errors..

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