Schema Registry Configuration Reference for Confluent Platform

This section contains Schema Registry configuration parameters organized by level of importance.

  • High: These parameters can have a significant impact on performance. Take care when deciding the values of these parameters.
  • Medium: These parameters can have some impact on performance. Your specific environment will determine how much tuning effort should be focused on these parameters.
  • Low: These parameters have a less general or less significant impact on performance.

These parameters are defined in the Schema Registry configuration file, schema-registry.properties, which is located at CONFLUENT_HOME/etc/schema-registry/schema-registry.properties) on a local install.

avro.compatibility.level

DEPRECATED: The Avro compatibility type.

Use schema.compatibility.level instead.

  • Type: string
  • Default: “backward”
  • Importance: high

access.control.allow.methods

Set value to Jetty Access-Control-Allow-Origin header for specified methods.

  • Type: string
  • Default: “”
  • Importance: low

access.control.allow.origin

Set value for Jetty Access-Control-Allow-Origin header.

  • Type: string
  • Default: “”
  • Importance: low

confluent.schema.registry.auth.ssl.principal.mapping.rules

A list of rules for mapping distinguished name (DN) from the client certificate to short name. The rules are evaluated in order and the first rule that matches a principal name is used to map it to a short name. Any later rules in the list are ignored. By default, DN of the X.500 certificate is the principal.

  • Type: list
  • Default: DEFAULT
  • Importance: low

debug

Boolean indicating whether extra debugging information is generated in some error response entities.

  • Type: boolean
  • Default: false
  • Importance: low

enable.fips

Enable FIPS mode on the server. If FIPS mode is enabled, broker listener security protocols, TLS versions and cipher suites will be validated based on FIPS compliance requirement.

Important

If set to true, the init.resource.extension.class configuration must be present, and it must contain io.confluent.kafka.schemaregistry.security.SchemaRegistryFipsResourceExtension.

  • Type: boolean
  • Default: false
  • Importance: low

exporter.config.topic

The topic used to persist exporter configs. This option is specific to schema exporters.

  • Type: string
  • Default: “_exporter_configs”
  • Importance: high

exporter.state.topic

The topic used to persist exporter states. This option is specific to schema exporters.

  • Type: string
  • Default: “_exporter_states”
  • Importance: high

exporter.max.exporters

Maximum number of exporters per tenant. This option is specific to schema exporters.

  • Type: int
  • Default: 10
  • Importance: low

exporter.num.threads

The number of threads for performing exports. This option is specific to schema exporters.

  • Type: int
  • Default: 10
  • Importance: low

exporter.max.retries

Maximum number of times to retry exporter operations. This option is specific to schema exporters.

  • Type: int
  • Default: 3
  • Importance: low

exporter.retries.wait.ms

Specifies the time in milliseconds to wait before each retry. This option is specific to schema exporters.

  • Type: int
  • Default: 1000
  • Importance: low

host.name

The advertised host name. Make sure to set this if running Schema Registry with multiple nodes. Starting with Confluent Platform 7.4.0, this name is always used in the endpoint for communication between Schema Registry instances, even if inter.instance.listener.name is specified, or does not match any listener. (The schema, port and TLS configurations will continue to be picked based on the inter.instance.listener.name config, if it is set.)

  • Type: string
  • Default: “192.168.50.1”
  • Importance: high

Important

If host.name is set in a multi Schema Registry node environment, it must resolve to a valid location or URL from the other Schema Registry instance(s) to ensure communication between the nodes.

host.http.connect.timeout.ms

The HTTP connection timeout in milliseconds for Schema Registry client. Specifies the maximum amount of time that a client will wait for a response from Schema Registry when attempting to connect before timing out (giving up). The default is 60000 milliseconds (60 seconds). This is now configurable on Confluent Platform 6.0 and later.

  • Type: int
  • Default: 60000
  • Valid Values: [0,…]
  • Importance: low

http.read.timeout.ms

The HTTP read timeout in milliseconds for Schema Registry client. Specifies the maximum amount of time that a client will wait for a response from Schema Registry on a READ attempt (for example, to retrieve a schema), before timing out (giving up). The default is 60000 milliseconds (60 seconds). This is now configurable on Confluent Platform 6.0 and later.

  • Type: int
  • Default: 60000
  • Valid Values: [0,…]
  • Importance: low

init.resource.extension.class

A list of classes to use as SchemaRegistryResourceExtension. Implementing the interface SchemaRegistryResourceExtension allows you to inject user defined resources to Schema Registry. These resources will be injected before Schema Registry is initialized.

  • Type: list
  • Default: []
  • Importance: low

inter.instance.protocol

The protocol used while making calls between the instances of Schema Registry. The secondary to primary node calls for writes and deletes will use the specified protocol. The default value would be http. When https is set, ssl.keystore and ssl.truststore configurations are used while making the call. (Use instead of the deprecated schema.registry.inter.instance.protocol.) If inter.instance.protocol and inter.instance.listener.name are both set, inter.instance.listener.name takes precedence.

  • Type: string
  • Default: “http”
  • Importance: low

inter.instance.listener.name

Name of listener used for communication between Schema Registry instances. If this value is unset, the listener used is defined by inter.instance.protocol. If both properties are set at the same time, inter.instance.listener.name takes precedence.

  • Type: string
  • Default: “”
  • Importance: low

kafkastore.bootstrap.servers

A list of Kafka brokers to connect to. For example, PLAINTEXT://hostname:9092,SSL://hostname2:9092

The Kafka cluster containing the bootstrap servers specified in kafkastore.bootstrap.servers is used to coordinate Schema Registry instances (leader election), and store schema data. When Kafka security is enabled, kafkastore.bootstrap.servers is also used to specify security protocols that Schema Registry uses to connect to Kafka.

  • Type: list
  • Default: []
  • Importance: medium

kafkastore.connection.url

REMOVED AS A METHOD OF CONFIGURING LEADER ELECTION: For leader election, use kafkastore.bootstrap.servers instead of kafkastore.connection.url.

Important

ZooKeeper URL for the Apache Kafka® cluster

  • Type: string
  • Default: “”
  • Importance: high

kafkastore.ssl.cipher.suites

A list of cipher suites used for SSL.

  • Type: string
  • Default: “”
  • Importance: low

kafkastore.ssl.endpoint.identification.algorithm

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

  • Type: string
  • Default: https
  • Importance: low

kafkastore.ssl.keymanager.algorithm

The algorithm used by key manager factory for TLS connections.

  • Type: string
  • Default: “SunX509”
  • Importance: low

kafkastore.ssl.trustmanager.algorithm

The algorithm used by the trust manager factory for TLS connections.

  • Type: string
  • Default: “PKIX”
  • Importance: low

kafkastore.zk.session.timeout.ms

ZooKeeper session timeout

  • Type: int
  • Default: 30000
  • Importance: low

kafkastore.ssl.key.password

The password of the key contained in the keystore.

  • Type: string
  • Default: “”
  • Importance: high

kafkastore.ssl.keystore.location

The location of the TLS keystore file.

  • Type: string
  • Default: “”
  • Importance: high

kafkastore.ssl.keystore.password

The password to access the keystore.

  • Type: string
  • Default: “”
  • Importance: high

kafkastore.ssl.truststore.location

The location of the TLS trust store file.

  • Type: string
  • Default: “”
  • Importance: high

kafkastore.ssl.truststore.password

The password to access the trust store.

  • Type: string
  • Default: “”
  • Importance: high

kafkastore.topic

The durable single partition topic that acts as the durable log for the data. This topic must be compacted to avoid losing data due to retention policy.

  • Type: string
  • Default: “_schemas”
  • Importance: high

kafkastore.topic.replication.factor

The desired replication factor of the schema topic. The actual replication factor will be the smaller of this value and the number of live Kafka brokers.

  • Type: int
  • Default: 3
  • Importance: high

kafkastore.init.timeout.ms

The timeout for initialization of the Kafka store, including creation of the Kafka topic that stores schema data.

  • Type: int
  • Default: 60000
  • Importance: medium

kafkastore.security.protocol

The security protocol to use when connecting with Kafka, the underlying persistent storage. Values can be PLAINTEXT, SASL_PLAINTEXT, SSL or SASL_SSL.

  • Type: string
  • Default: “PLAINTEXT”
  • Importance: medium

kafkastore.ssl.enabled.protocols

The comma-separated list of protocols enabled for TLS connections. The default value is TLSv1.2,TLSv1.3 when running with Java 11 or later, TLSv1.2 otherwise. With the default value for Java 11 (TLSv1.2,TLSv1.3), Kafka clients and brokers prefer TLSv1.3 if both support it, and falls back to TLSv1.2 otherwise (assuming both support at least TLSv1.2).

  • Type: string
  • Default: “TLSv1.2, TLSv1.3”
  • Importance: medium

kafkastore.ssl.keystore.type

The file format of the keystore.

  • Type: string
  • Default: “JKS”
  • Importance: medium

kafkastore.ssl.protocol

The TLS 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 might be supported in older JVMs, but their usage is discouraged due to known security vulnerabilities. With the default value for this configuration and ssl.enabled.protocols, clients downgrade to TLSv1.2 if the server does not support TLSv1.3. If this configuration is set to TLSv1.2, clients do 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
  • Importance: medium

kafkastore.ssl.provider

The name of the security provider used for SSL.

  • Type: string
  • Default: “”
  • Importance: medium

kafkastore.ssl.truststore.type

The file format of the trust store.

  • Type: string
  • Default: “JKS”
  • Importance: medium

kafkastore.timeout.ms

The timeout for an operation on the Kafka store

  • Type: int
  • Default: 500
  • Importance: medium

kafkastore.sasl.kerberos.service.name

The Kerberos principal name that the Kafka client runs as. This can be defined either in the JAAS config file or here.

  • Type: string
  • Default: “”
  • Importance: medium

kafkastore.sasl.mechanism

The SASL mechanism used for Kafka connections. GSSAPI is the default.

  • Type: string
  • Default: “GSSAPI”
  • Importance: medium

kafkastore.sasl.kerberos.kinit.cmd

The Kerberos kinit command path.

  • Type: string
  • Default: “/usr/bin/kinit”
  • Importance: low

kafkastore.sasl.kerberos.min.time.before.relogin

The login time between refresh attempts.

  • Type: long
  • Default: 60000
  • Importance: low

kafkastore.sasl.kerberos.ticket.renew.jitter

The percentage of random jitter added to the renewal time.

  • Type: double
  • Default: 0.05
  • Importance: low

kafkastore.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
  • Importance: low

kafkastore.group.id

Use this setting to override the group.id for the KafkaStore consumer. This setting can become important when security is enabled, to ensure stability over Schema Registry consumer’s group.id

Without this configuration, group.id will be schema-registry-<host>-<port>.

  • Type: string
  • Default: “”
  • Importance: low

leader.eligibility

If true, this node can participate in primary election. In a multi-colocated setup, turn this off for clusters in the secondary data center.

  • Type: boolean
  • Default: true
  • Importance: medium

listeners

Comma-separated list of listeners that listen for API requests over either HTTP or HTTPS. If a listener uses HTTPS, the appropriate TLS configuration parameters need to be set as well.

Schema Registry identities are stored in ZooKeeper and are made up of a hostname and port. If multiple listeners are configured, the first listener’s port is used for its identity.

  • Type: list
  • Default: “http://0.0.0.0:8081”
  • Importance: high

metadata.encoder.topic

The durable single partition topic that acts as the durable log for the encoder keyset.

  • Type: string
  • Default: “_schema_encoders”
  • Importance: high

metric.reporters

A list of classes to use as metrics reporters. Implementing the MetricReporter interface allows plugging in classes that will be notified of new metric creation. The JmxReporter is always included to register JMX statistics.

  • Type: list
  • Default: []
  • Importance: low

metrics.jmx.prefix

Prefix to apply to metric names for the default JMX reporter.

  • Type: string
  • Default: “kafka.schema.registry”
  • Importance: low

metrics.num.samples

The number of samples maintained to compute metrics.

  • Type: int
  • Default: 2
  • Importance: low

metrics.sample.window.ms

The metrics system maintains a configurable number of samples over a fixed window size. This configuration controls the size of the window. For example you might maintain two samples each measured over a 30 second period. When a window expires, you erase and overwrite the oldest window.

  • Type: long
  • Default: 30000
  • Importance: low

password.encoder.secret

The secret used for encoding dynamically configured passwords for this server. This option is specific to schema exporters.

  • Type: secret
  • Default: null
  • Importance: medium

password.encoder.old.secret

The old secret that was used for encoding dynamically configured passwords. This is required only when the secret is updated. If specified, all dynamically encoded passwords are decoded using this old secret and re-encoded using password.encoder.secret when server starts up.

This option is specific to schema exporters.

  • Type: password
  • Default: null
  • Importance: medium

port

DEPRECATED: port to listen on for new connections.

Use listeners instead.

  • Type: int
  • Default: 8081
  • Importance: low

proxy.host

Hostname or IP address of the proxy server that will be used to connect to the Schema Registry instances.

  • Type: string
  • Default: “”
  • Importance: low

proxy.port

Port number of the proxy server that will be used to connect to the Schema Registry instances.

  • Type: string
  • Default: “”
  • Importance: low

response.mediatype.default

The default response media type that should be used if no specify types are requested in an Accept header.

  • Type: string
  • Default: “application/vnd.schemaregistry.v1+json”
  • Importance: high

response.mediatype.preferred

An ordered list of the server’s preferred media types used for responses, from most preferred to least.

  • Type: list
  • Default: [application/vnd.schemaregistry.v1+json, application/vnd.schemaregistry+json, application/json]
  • Importance: high

response.http.headers.config

Usetoselect which HTTP headers are returned in the HTTP response for Confluent Platform components. Specify multiple values in a comma-separated string using the format [action][header name]:[header value] where [action] is one of the following: set, add, setDate, or addDate. You must use quotation marks around the header value when the header value contains commas. For example:

response.http.headers.config="add Cache-Control: no-cache, no-store, must-revalidate", add X-XSS-Protection: 1; mode=block, add Strict-Transport-Security: max-age=31536000; includeSubDomains, add X-Content-Type-Options: nosniff
  • Type: string
  • Default: “”
  • Importance: low

request.logger.name

Name of the SLF4J logger to write the NCSA Common Log Format request log.

  • Type: string
  • Default: “io.confluent.rest-utils.requests”
  • Importance: low

resource.extension.class

Fully qualified class name of a valid implementation of the interface SchemaRegistryResourceExtension. This can be used to inject user defined resources like filters. Typically used to add custom capability like logging, security, etc. (Use resource.extension.class instead of deprecated schema.registry.resource.extension.class.)

  • Type: list
  • Default: []
  • Importance: low

schema.canonicalize.on.consume

A list of Formats, Serializers, and Deserializers (AVRO, JSON, or PROTOBUF) to canonicalize on consume. Use this parameter if canonicalization changes.

  • Type: string
  • Default: “”
  • Importance: high

schema.compatibility.level

The schema compatibility type.

Valid values are:

  • none: New schema can be any valid schema.
  • backward: New schema can read data produced by latest registered schema.
  • backward_transitive: New schema can read data produced by all previously registered schemas.
  • forward: Latest registered schema can read data produced by the new schema.
  • forward_transitive: All previously registered schemas can read data produced by the new schema.
  • full: New schema is backward and forward compatible with latest registered schema.
  • full_transitive: New schema is backward and forward compatible with all previously registered schemas.

In Confluent Platform versions 5.5.0 and later, use schema.compatibility.level instead of the deprecated avro-compatibility-level instead.

  • Type: string
  • Default: “backward”
  • Importance: high

See also

schema.linking.rbac.enable

Whether or not to enable and enforce role-based access control (RBAC) for Link Schemas on Confluent Platform on Confluent Platform. To learn more, see Access Control (RBAC) for Schema Linking Exporters.

  • Type: boolean
  • Default: false
  • Importance: medium

schema.registry.group.id

Schema Registry cluster ID takes its name from the Schema Registry group ID.

  • Type: string
  • Default: “schema-registry”
  • Importance: low

See also

schema.registry.inter.instance.protocol

DEPRECATED: The protocol used while making calls between the instances of Schema Registry. The secondary-to-primary node calls for writes and deletes will use the specified protocol. The default value would be http. When https is set, ssl.keystore and ssl.truststore configs are used while making the call. If both schema.registry.inter.instance.protocol and inter.instance.listener.name are both set, inter.instance.listener.name takes precedence.

Use inter.instance.protocol instead.

  • Type: string
  • Default: “”
  • Importance: low

schema.registry.resource.extension.class

DEPRECATED: Fully qualified class name of a valid implementation of the interface SchemaRegistryResourceExtension. This can be used to inject user defined resources like filters. Typically used to add custom capability like logging, security, etc.

Use resource.extension.class instead.

  • Type: string
  • Default: “”
  • Importance: low

schema.registry.zk.namespace

DEPRECATED: Configure schema.registry.group.id if you originally had schema.registry.zk.namespace for multiple Schema Registry clusters.

Important

The string that is used as the ZooKeeper namespace for storing Schema Registry metadata. Schema Registry instances which are part of the same Schema Registry service should have the same ZooKeeper namespace.

  • Type: string
  • Default: “schema_registry”
  • Importance: low

schema.search.default.limit

Default limit on number of schemas returned per schema search.

  • Type: int
  • Default: 1000
  • Importance: low

schema.search.max.limit

Maximum number of schemas returned per schema search.

  • Type: int
  • Default: 1000
  • Importance: low

shutdown.graceful.ms

Amount of time to wait after a shutdown request for outstanding requests to complete.

  • Type: int
  • Default: 1000
  • Importance: low

ssl.keystore.location

Used for HTTPS. Location of the keystore file to use for SSL.

Important

Jetty requires that the key’s CN, stored in the keystore, must match the FQDN.

  • Type: string
  • Default: “”
  • Importance: high

ssl.keystore.password

Used for HTTPS. The store password for the keystore file.

  • Type: password
  • Default: “”
  • Importance: high

ssl.key.password

Used for HTTPS. The password of the private key in the keystore file.

  • Type: password
  • Default: “”
  • Importance: high

ssl.truststore.location

Used for HTTPS. Location of the trust store. Required only to authenticate HTTPS clients.

  • Type: string
  • Default: “”
  • Importance: high

ssl.truststore.password

Used for HTTPS. The store password for the trust store file.

  • Type: password
  • Default: “”
  • Importance: high

ssl.keystore.type

Used for HTTPS. The type of keystore file.

  • Type: string
  • Default: “JKS”
  • Importance: medium

ssl.truststore.type

Used for HTTPS. The type of trust store file.

  • Type: string
  • Default: “JKS”
  • Importance: medium

ssl.protocol

The TLS 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 might be supported in older JVMs, but their usage is discouraged due to known security vulnerabilities. With the default value for this configuration and ssl.enabled.protocols, clients downgrade to TLSv1.2 if the server does not support TLSv1.3. If this configuration is set to TLSv1.2, clients do 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
  • Importance: medium

ssl.provider

Used for HTTPS. The TLS security provider name. Leave blank to use Jetty’s default.

  • Type: string
  • Default: “” (Jetty’s default)
  • Importance: medium

ssl.client.auth

DEPRECATED: Used for HTTPS. Whether or not to require the HTTPS client to authenticate via the server’s trust store. Use ssl.client.authentication instead.

  • Type: boolean
  • Default: false
  • Importance: medium

ssl.client.authentication

Used for HTTPS. Whether to require the HTTPS client to authenticate using the server’s trust store.

Valid values are NONE, REQUESTED or REQUIRED. NONE disables TLS client authentication, REQUESTED requests but does not require TLS client authentication, and REQUIRED requires TLS HTTPS clients to authenticate using the server’s truststore. This configuration overrides the deprecated ssl.client.auth.

  • Type: string
  • Default: NONE
  • Importance: medium

ssl.enabled.protocols

Used for HTTPS. Leave blank ("") to use Jetty’s defaults. The comma-separated list of protocols enabled for TLS connections. The default value is TLSv1.2,TLSv1.3 when running with Java 11 or later, TLSv1.2 otherwise. With the default value for Java 11 (TLSv1.2,TLSv1.3), Kafka clients and brokers prefer TLSv1.3 if both support it, and falls back to TLSv1.2 otherwise (assuming both support at least TLSv1.2).

  • Type: list
  • Default: “” (Jetty’s default)
  • Importance: medium

ssl.principal.mapping.rules

Used for HTTPS. A list of rules for mapping distinguished name (DN) from the client certificate to short name. The rules are evaluated in order and the first rule that matches a principal name is used to map it to a short name. Any later rules in the list are ignored. By default, DN of the X.500 certificate is the principal. For details see mTLS to SASL Authentication.

For Schema Registry use: confluent.schema.registry.auth.ssl.principal.mapping.rules.

  • Type: list
  • Default: “DEFAULT”
  • Importance: low

ssl.keymanager.algorithm

Used for HTTPS. The algorithm used by the key manager factory for TLS connections. Leave blank to use Jetty’s default.

  • Type: string
  • Default: “” (Jetty’s default)
  • Importance: low

ssl.trustmanager.algorithm

Used for HTTPS. The algorithm used by the trust manager factory for TLS connections. Leave blank to use Jetty’s default.

  • Type: string
  • Default: “” (Jetty’s default)
  • Importance: low

ssl.cipher.suites

Used for HTTPS. A list of TLS cipher suites. Comma-separated list. Leave blank to use Jetty’s defaults.

  • Type: list
  • Default: “” (Jetty’s default)
  • Importance: low

ssl.endpoint.identification.algorithm

Used for HTTPS. The endpoint identification algorithm to validate the server hostname using the server certificate. Leave blank to use Jetty’s default.

  • Type: string
  • Default: “” (Jetty’s default)
  • Importance: low

zookeeper.set.acl

Whether or not to set an ACL in ZooKeeper when znodes are created and ZooKeeper SASL authentication is configured.

Important

If set to true, the ZooKeeper SASL principal must be the same as the Kafka brokers.

  • Type: boolean
  • Default: false
  • Importance: high

License for Schema Registry Security Plugin

A Confluent Platform enterprise license is required for the Schema Registry Security Plugin for Confluent Platform.

For details on how to configure the plugin, including confluent.license, see the configuration options in Install and Configure the Schema Registry Security Plugin for Confluent Platform.