Appendix F. Kafka Connect configuration parameters

Type: string
Importance: high

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

Type: string
Importance: high

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

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.

Type: string
Importance: high

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

Type: string
Importance: high

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

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.

Type: list
Default: localhost:9092
Importance: high

A list of host/port pairs to use for establishing the initial connection to the Kafka cluster. The client will make use of all servers irrespective of which servers are specified here for bootstrapping—this list only impacts the initial hosts used to discover the full set of servers. This list should be in the form host1:port1,host2:port2,…​. Since these servers are just used for the initial connection to discover the full cluster membership (which may change dynamically), this list need not contain the full set of servers (you may want more than one, though, in case a server is down).

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.

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.

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.

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'. This is required for clients only if two-way authentication is configured.

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.

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'.

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.

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.

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.

Type: string
Default: null
Importance: high

The location of the trust store file.

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.

Type: string
Default: use_all_dns_ips
Valid Values: [default, 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. If set to default (deprecated), attempt to connect to the first IP address returned by the lookup, even if the lookup returns multiple IP addresses.

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

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

Type: string
Default: None
Importance: medium

Class name or alias of implementation of ConnectorClientConfigOverridePolicy. Defines what client configurations can be overriden by the connector. The default implementation is None. The other possible policies in the framework include All and Principal.

Type: int
Default: 32768 (32 kibibytes)
Valid Values: [0,…​]
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.

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.

Type: class
Default: null
Importance: medium

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

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;.

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.

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.

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.

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.

Type: string
Default: PLAINTEXT
Importance: medium

Protocol used to communicate with brokers. Valid values are: PLAINTEXT, SSL, SASL_PLAINTEXT, SASL_SSL.

Type: int
Default: 131072 (128 kibibytes)
Valid Values: [0,…​]
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.

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

The list of protocols enabled for SSL connections. The default is 'TLSv1.2,TLSv1.3' when running with Java 11 or newer, 'TLSv1.2' otherwise. With the default value for Java 11, 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 cases. Also see the config documentation for ssl.protocol.

Type: string
Default: JKS
Importance: medium

The file format of the key store file. This is optional for client.

Type: string
Default: TLSv1.3
Importance: medium

The SSL protocol used to generate the SSLContext. The default is 'TLSv1.3' when running with Java 11 or newer, 'TLSv1.2' otherwise. This value should be fine for most use cases. Allowed values in recent JVMs are 'TLSv1.2' and 'TLSv1.3'. 'TLS', 'TLSv1.1', 'SSL', 'SSLv2' and 'SSLv3' may be supported in older JVMs, but their usage is discouraged due to known security vulnerabilities. With the default value for this config and 'ssl.enabled.protocols', clients will downgrade to 'TLSv1.2' if the server does not support 'TLSv1.3'. If this config is set to 'TLSv1.2', 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: null
Importance: medium

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

Type: string
Default: JKS
Importance: medium

The file format of the trust store file.

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.

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.

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.

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.

Type: list
Default: null
Valid Values: org.apache.kafka.connect.runtime.WorkerConfig$AdminListenersValidator@6e3c1e69
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).

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.

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.

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.

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

Compatibility mode for Kafka Connect Protocol.

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.

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.

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.

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).

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

The algorithm used to sign internal requests.

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.

Type: class
Default: org.apache.kafka.connect.json.JsonConverter
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. This setting controls the format used for internal bookkeeping data used by the framework, such as configs and offsets, so users can typically use any functioning Converter implementation. Deprecated; will be removed in an upcoming version.

Type: class
Default: org.apache.kafka.connect.json.JsonConverter
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. This setting controls the format used for internal bookkeeping data used by the framework, such as configs and offsets, so users can typically use any functioning Converter implementation. Deprecated; will be removed in an upcoming version.

Type: list
Default: null
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.

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.

Type: list
Default: ""
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. The JmxReporter is always included to register JMX statistics.

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

The number of samples maintained to compute metrics.

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

The highest recording level for metrics.

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

The window of time a metrics sample is computed over.

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

Interval at which to try committing offsets for tasks.

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.

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.

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.

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.

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.

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.

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.

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.

Type: string
Default: null
Importance: low

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

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.

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.

Type: string
Default: null
Importance: low

Hostname for the REST API. If this is set, it will only bind to this interface.

Type: int
Default: 8083
Importance: low

Port for the REST API to listen on.

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.

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

Kerberos kinit command path.

Type: long
Default: 60000
Importance: low

Login thread sleep time between refresh attempts.

Type: double
Default: 0.05
Importance: low

Percentage of random jitter added to the renewal time.

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.

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.

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.

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.

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.

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.

Type: long
Default: 127000 (127 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.

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.

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.

Type: string
Default: none
Importance: low

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

Type: string
Default: https
Importance: low

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

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.

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.

Type: string
Default: null
Importance: low

The SecureRandom PRNG implementation to use for SSL cryptography operations.

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.

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.

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.

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.

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.

Type: boolean
Default: true
Importance: low

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

Type: boolean
Default: true
Importance: low

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