[KAFKA-13742] Quota byte-rate/request metrics are loaded only when at least one quota is register

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Component/s: core, metrics
• Labels: quotas
• Assignee: Unassigned
• Reporter: Jorge Esteban Quilcate Otoya
• Created: 15/Mar/22 16:44
• Updated: 18/Mar/22 00:06
• Resolved: 18/Mar/22 00:06

Description

Quota metrics are loaded only when at least one quota is present:

• Metrics: https://github.com/apache/kafka/blob/0b9a8bac36f16b5397e9ec3a0441758e4b60a384/core/src/main/scala/kafka/server/ClientQuotaManager.scala#L552-L563
• Reporting when quotas are enabled: https://github.com/apache/kafka/blob/0b9a8bac36f16b5397e9ec3a0441758e4b60a384/core/src/main/scala/kafka/server/ClientQuotaManager.scala#L249-L256
• Quotas enabled: `def quotasEnabled: Boolean = quotaTypesEnabled != QuotaTypes.NoQuotas`

Even though throttling is specific for quotas, byte-rate/request per user/client-id is a valid metric for any deployment.

 

The current workaround is to add any quota, as this will enable metrics for all client-id/users.

If these metrics are captured for all clients regardless of the quotas created, it would be a better experience to have a config to opt-in into these metrics instead of creating meaningless quotas just to get these metrics.

For threshold metrics, it makes sense to me to enable them only when quotas are enabled.