Unsupported API requests

Alert: KrabkaUnsupportedApiRequests, sum by (instance, api_key) (rate(krabka_broker_unsupported_api_requests_total[5m])) > 0 for 5m.

What it means

A client sends requests at an api_key and version pair the broker does not register. The dispatcher rejects each one with UNSUPPORTED_VERSION and the client normally retries. A well-behaved client negotiates with ApiVersions first and never lands here. The usual causes are a client that skips negotiation, a client pinned to a version the broker does not speak, or a broker fleet in the middle of a rolling upgrade.

Confirm

The api_key label names the API. krabka_broker_client_software_versions_total lists the client libraries that connected. The broker log records the peer address and the version it asked for.

Diagnose

1. Compare the version the client asks for with the broker’s advertised range: kafka-broker-api-versions --bootstrap-server <broker>:9092.
2. If the fleet is mid-upgrade, a client that learned the range from a new broker may send the same version to an old one. The alert clears when the roll completes.
3. If one client software name is the source, that client has a pinned version. Find the owner through the peer address in the log.

Fix

• Finish the rolling upgrade. See deploy.
• Reconfigure or upgrade the client. krabka follows Kafka’s version ranges, so a client that works against the current Kafka release works here.
• If the API is one krabka does not implement at that version, check KIP_MATRIX.md and open an issue with the api_key and version.