Klag vs KMinion

Klag and KMinion are both Prometheus exporters for Kafka. They overlap on consumer-lag basics but emphasize different things: KMinion casts a wider net across broker/topic/log-dir metrics; Klag goes deeper on consumer-lag analysis and ships to Datadog and OTLP as well as Prometheus.

What each tool is

• Klag is a consumer-lag exporter focused on lag depth: velocity, time-based lag, retention risk, hot partitions, and commit staleness, exported to Prometheus, Datadog, or OTLP. Its cluster-adjacent scope is limited to partition offsets, under-replicated partitions, and topic partition counts; it has no broker or log-dir metrics.
• KMinion is a broad Prometheus exporter covering consumer-group lag plus broker, topic, and log-directory metrics. It also runs optional end-to-end produce/consume probes to measure roundtrip latency.

At a glance

	Klag	KMinion
Category	Consumer-lag exporter	General Prometheus exporter
Runtime	Java / Vert.x / GraalVM	Go
Primary output	Prometheus, Datadog, OTLP	Prometheus
Emphasis	Deep consumer-lag signals	Broad cluster metrics
License	Apache 2.0	MIT

Feature comparison

Feature	Klag	KMinion
Lag in messages	✅	✅
Consumer group state	✅	✅
Topic / partition metrics	⚠️ limited	✅ broad
Broker / log-dir metrics	❌	✅
End-to-end latency probes	❌	✅
Lag velocity (growing/shrinking)	✅	❌
Time-based lag (ms) + time-to-catch-up	✅	❌
Hot partition detection	✅	❌
Data-loss / retention alerting	✅	❌
Commit staleness (stuck consumers)	✅	❌
MCP endpoint for AI agents	✅	❌
Datadog / OTLP native	✅	❌
Read-only DESCRIBE ACLs	✅	⚠️ writes for e2e probes
GraalVM native image (~44 MB RSS)	✅	❌

When to use which

• Use KMinion if you want one exporter for broad cluster health — broker metrics, topic configs, log-dir sizes, and optional end-to-end latency probes — all in Prometheus.
• Use Klag if consumer lag is the priority and you want the deeper signals (velocity, time-based lag, retention risk, hot partitions, commit staleness) plus Datadog/OTLP output and an MCP endpoint for AI agents. Note KMinion’s end-to-end probes produce and consume test messages, so it needs write access; Klag is strictly read-only (DESCRIBE).

The two aren’t mutually exclusive — some teams run KMinion for broker/topic breadth and Klag for consumer-lag depth.

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