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1. IL-0246 New pods on Adyen's big data Kubernetes nodes could not start, failing with "Cilium API client timeout exceeded"

   Adyen2026

   Symptoms

   On Adyen's production big data Kubernetes clusters, new pods on some nodes could not start because setting up their network through Cilium timed out. Once one pod had timed out, every other pod trying to start on the same node timed out as well.

   Pods stuck in ContainerCreating

   Trigger

   Heavy data workloads landed on nodes where the interval of Cilium's periodic garbage collection of expired connection tracking entries had grown, during a quiet period, toward its 12-hour maximum.

   Root cause

   Configuration change

   Component

   Cilium

   Contributing factor

   Change with a delayed effectUnreviewed defaultsRetry stormNo alert on limit

   Remediation

   • Set a fixed connection tracking garbage collection interval, conntrackGCInterval: 60s, and rolled it out to the Cilium DaemonSet

   Action items

   • Alert on the connection tracking garbage collection duration and table size metrics

   Lessons

   Scaling parameters can interact with other logic months later as traffic grows: the larger table that solved capacity limits on 512GB nodes interacted with the garbage collection auto-scaling on the 2TB nodes. Logs only showed symptoms, so profiling and tracing across the container runtime, the CNI plugin, the Cilium agent and the kernel were needed, and simple arithmetic with measured numbers pointed at the cause early. Auto-scaling algorithms need bounds, and the 12-hour maximum interval was too long for this workload. A timeout protects the caller but does not cancel the work behind it. Adyen recommends that Cilium deployments with dynamic workloads alert on cilium_datapath_conntrack_gc_duration_seconds and cilium_datapath_conntrack_gc_entries and set conntrackGCInterval: 60s.

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