Monitor Schema Registry in Confluent Platform

Schema Registry reports a variety of metrics through Java Management Extensions (JMX). It can also be configured to report stats using additional pluggable stats reporters using the metric.reporters configuration option. The easiest way to view the available metrics is to use JConsole to browse JMX MBeans.

Schema Registry has two types of metrics. Global metrics help you monitor the overall health of the service. Per-endpoint metrics monitor each API endpoint request method and are prefixed by a name of the endpoint (e.g. subjects.get-schema). These help you understand how the proxy is being used and track down specific performance problems.

Tip

Authentication is disabled for JMX by default in Kafka. You must use environment variables to override these defaults. For each platform component, the options to override the JMX defaults take the form <component-name>_JMX_OPTS. Use the following environment variable to override default JMX options for Schema Registry: SCHEMA_REGISTRY_JMX_OPTS.

Global Metrics

MBean: kafka.schema.registry:type=jetty-metrics

connections-active

Total number of active TCP connections.

connections-accepted-rate (deprecated since 2.0)

• In 1.x: The average rate per second of accepted TCP connections.

• In 2.x: Same as connections-opened-rate.

connections-opened-rate

The average rate per second of opened TCP connections.

connections-closed-rate

The average rate per second of closed TCP connections.

busy_thread_count

The number of threads currently working on a task (busy threads).

thread_pool_usage

Percentage of total thread pool in use (total/threads in use).

request_queue_size

Number of threads required for requests in the queue.

MBean: kafka.schema.registry:type=master-slave-role

master-slave-role

The current role of this Schema Registry instance. A value of 1 indicates this instance is the primary, 0 indicates it is a secondary.

MBean: kafka.schema.registry:type=exporter

Schema Registry reports the following metrics for the schema exporters you create with Schema Linking. Each metric carries tags on its object name that identify the exporter, such as exporter_name and tenant. To browse the full set in a JMX client such as JConsole, filter on kafka.schema.registry:type=exporter,*.

exporter_tasks

The number of exporter tasks in each state (UNASSIGNED, STARTING, RUNNING, or PAUSED). Tagged with exporter_name, exporter_state, has_error, and is_retriable.

exporter_starting_progress

The progress of an exporter that is starting. Tagged with exporter_name.

schema_transfer_success_total

The total number of successful schema register calls made by the exporter. This can exceed the number of unique schemas, since a schema with multiple versions registers each version separately. Tagged with exporter_name.

exporter_objects_sync_total

The total number of objects synced successfully, including schemas, Key Encryption Keys (KEKs), Data Encryption Keys (DEKs), and deletes. Unlike schema_transfer_success_total, this metric also counts non-schema objects. Tagged with exporter_name, object_type, and operation.

exporter_lifecycle_latency

The wall-clock duration of the exporter’s most recent lifecycle phase (for example, STARTING or RUNNING), in milliseconds. This measures time spent in that phase, not the latency of an individual schema export. Tagged with exporter_name and exporter_state.

exporters_errored_total

The number of times an exporter moved to the PAUSED state because of an exception or error. Tagged with exporter_name, error_type, and operation.

exporter_service_start_failure_total

The number of schema exporter service failures. This metric applies to the service as a whole, so it has no exporter tags.

Per-Endpoint Metrics

The following are the metrics available for each endpoint request method. Metrics for all requests are also aggregated into a global instance for each one. These aggregate instances have no prefix in their name.

MBean: kafka.schema.registry:type=jersey-metrics

<endpoint>.request-byte-rate

Bytes/second of incoming requests

<endpoint>.request-error-rate

The average number of requests per second that resulted in HTTP error responses

<endpoint>.request-latency-avg

The average request latency in ms

<endpoint>.request-latency-max

The maximum request latency in ms

<endpoint>.request-rate

The average number of HTTP requests per second.

<endpoint>.request-size-avg

The average request size in bytes

<endpoint>.request-size-max

The maximum request size in bytes

<endpoint>.response-byte-rate

Bytes/second of outgoing responses

<endpoint>.response-rate

The average number of HTTP responses per second.

<endpoint>.response-size-avg

The average response size in bytes

<endpoint>.response-size-max

The maximum response size in bytes

Endpoints

The following is a list of all the API endpoint methods. The naming should map intuitively to each of the API operations. To create a full metric name, prefix a per-endpoint metric name with one of these values. For example, to find the rate of GET /brokers API calls, combine the endpoint name brokers.list with the metric name request-rate to get brokers.list.request-rate.

compatibility.subjects.versions.verify	POST /compatibility/subjects/{subject}/versions/{version}
schemas.ids.get-schema	GET /schemas/ids/{id}
subjects.get-schema	POST /subjects/{subject}
subjects.list	GET /subjects
subjects.versions.get-schema	GET /subjects/{subject}/versions/{version}
subjects.versions.get-schema.only	GET /subjects/{subject}/versions/{version}/schema
subjects.versions.list	GET /subjects/{subject}/versions
subjects.versions.register	POST /subjects/{subject}/versions