Hubble Flow Buffer Saturation
warningResource ContentionUpdated Sep 2, 2025
When Hubble's flow buffer reaches 100% capacity, new flow events are dropped, creating observability blind spots. This occurs during traffic spikes or when flows/s exceeds buffer capacity, preventing accurate troubleshooting and policy validation.
Sources
How to detect:
Monitor 'Current/Max Flows' ratio from 'hubble status' output. When ratio approaches or reaches 100%, flow events are being dropped. Also track 'Flows/s' metric to identify sustained high flow rates that may cause buffer pressure.
Recommended action:
Increase Hubble flow buffer size by adjusting the max flows configuration in Cilium Helm values. Consider enabling flow sampling or filtering to reduce buffer pressure. For clusters with high connection rates, pre-emptively size buffers based on expected flows/s.