Broker Configuration Reference

This page lists the supported broker configuration for WarpStream. Configuration not listed here is either ignored (for non-WarpStream keys) or rejected (for unknown warpstream.* keys).

Configuration items that start with warpstream. are WarpStream-specific. Some native Kafka tooling may not handle these configs as expected.

Broker config in WarpStream is cluster-scoped: DescribeConfigs using an empty broker name or a concrete broker ID reflects the same effective cluster configuration.

auto.create.topics.enable

Whether topics can be auto-created when clients reference unknown topic names.

Type:	string (boolean)
Default:	true
Valid Values:	[true, false]

delete.topic.enable

Whether topic deletion is allowed.

Type:	string (boolean)
Default:	true
Valid Values:	[true, false]

group.consumer.heartbeat.interval.ms

Heartbeat interval for modern (KIP-848) consumer groups.

Type:	int
Default:	5000
Valid Values:	[1,2147483647] with cross-validation rules

group.consumer.max.heartbeat.interval.ms

Upper bound for modern-group heartbeat interval.

Type:	int
Default:	15000
Valid Values:	[1,2147483647] with cross-validation rules

group.consumer.max.session.timeout.ms

Upper bound for modern-group session timeout.

Type:	int
Default:	60000
Valid Values:	[1,2147483647] with cross-validation rules

group.consumer.max.size

Maximum allowed size for modern (KIP-848) consumer groups.

Type:	int
Default:	32000
Valid Values:	[1,2147483647]

group.consumer.min.heartbeat.interval.ms

Lower bound for modern-group heartbeat interval.

Type:	int
Default:	5000
Valid Values:	[1,2147483647] with cross-validation rules

group.consumer.min.session.timeout.ms

Lower bound for modern-group session timeout.

Type:	int
Default:	45000
Valid Values:	[1,2147483647] with cross-validation rules

group.consumer.session.timeout.ms

Session timeout for modern (KIP-848) consumer groups.

Type:	int
Default:	45000
Valid Values:	[1,2147483647] with cross-validation rules

log.retention.hours

Same setting as log.retention.ms, but expressed in hours.

Type:	long
Default:	24 (1 day)
Valid Values:	[-1,…]

log.retention.minutes

Same setting as log.retention.ms, but expressed in minutes.

Type:	long
Default:	1440 (1 day)
Valid Values:	[-1,…]

log.retention.ms

Default retention for topics, in milliseconds.

If set to a negative value, WarpStream treats retention as effectively infinite. If set to a positive value lower than 1 minute, WarpStream raises it to 1 minute.

Type:	long
Default:	86400000 (1 day)
Valid Values:	[-1,…,3153600000000]

message.max.bytes

Cluster-level record size cap.

If this value is not explicitly set, WarpStream may omit it from DescribeConfigs, because the effective default depends on agent-side limits.

Type:	int
Default:	agent-dependent (unset at cluster config layer)
Valid Values:	[0,…]

num.partitions

Default partition count used when topics are auto-created.

Type:	int
Default:	1
Valid Values:	[0, 4294967295]

offsets.retention.minutes

Retention for committed consumer group offsets.

Type:	long
Default:	10080 (7 days)
Valid Values:	[1,…]

warpstream.default.partitions_auto_scaler.enabled

Cluster-level default for topic config warpstream.partitions_auto_scaler.enabled.

This default is applied to newly created topics (including auto-created topics). If a topic explicitly sets warpstream.partitions_auto_scaler.enabled, the topic value takes precedence.

Type:	string (boolean)
Default:	false
Valid Values:	[true, false]

warpstream.default.partitions_auto_scaler.max_partition_count

Cluster-level default for topic config warpstream.partitions_auto_scaler.max_partition_count.

This default is applied to newly created topics. A value of 0 means unlimited. If a topic explicitly sets warpstream.partitions_auto_scaler.max_partition_count, the topic value takes precedence.

Type:	long
Default:	0 (unlimited)
Valid Values:	[0,…]

warpstream.default.partitions_auto_scaler.partition_count_multiple

Cluster-level default for topic config warpstream.partitions_auto_scaler.partition_count_multiple.

This default is applied to newly created topics. A value of 0 or 1 disables the constraint. If a topic explicitly sets warpstream.partitions_auto_scaler.partition_count_multiple, the topic value takes precedence.

Type:	long
Default:	0
Valid Values:	[0,…]

warpstream.default.partitions_auto_scaler.per_partition_throughput_uncompressed_bytes_per_second

Cluster-level default for topic config warpstream.partitions_auto_scaler.per_partition_throughput_uncompressed_bytes_per_second.

This default is applied to newly created topics. If a topic explicitly sets warpstream.partitions_auto_scaler.per_partition_throughput_uncompressed_bytes_per_second, the topic value takes precedence.

Type:	long
Default:	2500000
Valid Values:	[0,…]

warpstream.default.topic.type

Default topic type for newly created topics.

Type:	string
Default:	classic
Valid Values:	[classic, lightning]

warpstream.soft.delete.topic.enable

Whether soft-delete behavior is enabled for inactive topics.

Type:	string (boolean)
Default:	true
Valid Values:	[true, false]

warpstream.soft.delete.topic.ttl.hours

Inactive topic TTL in hours when soft-delete is enabled.

If set to a negative value, WarpStream treats TTL as effectively infinite.

Type:	long
Default:	24 (1 day)
Valid Values:	[-1,…]

group.consumer.* cross-validation rules

WarpStream enforces the following invariants for KIP-848 timing configs:

• group.consumer.max.heartbeat.interval.ms >= group.consumer.min.heartbeat.interval.ms
• group.consumer.heartbeat.interval.ms must be within [min.heartbeat, max.heartbeat]
• group.consumer.max.session.timeout.ms >= group.consumer.min.session.timeout.ms
• group.consumer.session.timeout.ms must be within [min.session, max.session]
• group.consumer.heartbeat.interval.ms < group.consumer.session.timeout.ms

Alter behavior

AlterConfigs uses classic replace semantics for known broker configs:

• keys present in request are set
• known keys omitted from request are reset/unset

IncrementalAlterConfigs supports:

• SET
• DELETE

APPEND and SUBTRACT are not supported for broker configs.

Unknown config behavior

• Unknown keys containing warpstream are rejected with INVALID_CONFIG.
• Unknown non-WarpStream keys are ignored for compatibility.

Kafka compatibility values returned by DescribeConfigs

WarpStream also reports a set of read-only Kafka-style broker config values for compatibility:

Config key	Value
compression.type	lz4
log.flush.interval.messages	1
log.retention.bytes	-1
unclean.leader.election.enable	false
broker.id.generation.enable	true
default.replication.factor	3
reserved.broker.max.id	2147483647

CLI examples

Using WarpStream CLI commands:

warpstream cli describe-broker-configs \
  -bootstrap-host localhost \
  -bootstrap-port 9092

warpstream cli alter-broker-config \
  -bootstrap-host localhost \
  -bootstrap-port 9092 \
  --add-config "warpstream.default.topic.type=lightning"