Introduction

Monitors the state of a Kafka consumer group during an experiment. This check polls the consumer group's coordination state and evaluates whether it matches the expected states.

This action targets consumer groups, not brokers or topics. For broker-level monitoring (controller elections, downtime), use Check Brokers. For topic partition changes (leader election, replica changes), use Check Partitions. For consumer lag monitoring, use Check Consumer Lag.

Use Cases

• Verify that a consumer group remains Stable while injecting faults into downstream services.
• Assert that a consumer group transitions to PreparingRebalance when a consumer pod is killed.
• Detect if a consumer group enters a Dead state during a broker fault injection.

Parameters

Parameter	Description	Default
Duration	How long the check runs. The check continuously polls consumer group state for this duration.	30s
Expected State List	(optional) Which consumer group states to expect. Valid values: Stable, Dead, Empty, Unknown, CompletingRebalance, PreparingRebalance. Multiple states can be selected — the check succeeds if the group is in any of the listed states.
State Check Mode	How the expected state is evaluated. All the time (allTheTime): every poll must find the consumer in one of the expected states. At least once (atLeastOnce): the expected state must be observed at least once during the duration.	allTheTime