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  1. IL-0085 A control plane node of Magic Pages' Kubernetes cluster on Hetzner Cloud ran out of memory, the cluster's own calls then used up the Hetzner API rate limit, and all customer websites were down for about 7.5 hours
    Magic Pages2025
    Symptoms

    At around 09:33 UTC one of the three control plane nodes of the Kubernetes cluster that hosts Magic Pages went offline. Looking at the node showed that it had run out of memory.

    Service outageNode NotReadyCloud API rate limit exhausted
    Trigger

    One of the three control plane nodes ran out of memory and went offline at about 09:33 UTC; the attempts to replace it with hetzner-k3s failed while the cluster's own components were exhausting the Hetzner API rate limit.

    Root cause
    Capacity exhaustion
    Component
    Cloud controller managerPersistent volumes and stateful sets
    Contributing factor
    Unknown limitRetry stormMonitoring blind spotLimited debug accessSingle point of failureNo runbook
    Detection

    The founder found the control plane node offline at about 09:33 UTC. Monitoring alerts about unreachable customer websites started around the time the replacement attempts failed, and about half an hour of investigation identified the exhausted Hetzner API rate limit.

    Remediation
    • powered off all servers of the Kubernetes cluster to stop the API requests so the Hetzner rate limit could recover
    • waited until ratelimit-remaining had built up a buffer before starting recovery
    • restarted the control plane servers
    • started the essential Longhorn components by hand so Longhorn could heal and make storage volumes available
    • restarted the remaining websites by hand
    Action items
    • Monitor the Hetzner API call rate coming from the Kubernetes cluster nodes themselves to get early warning of high usage
    • Get a higher Hetzner API rate limit; Hetzner support was contacted
    • Investigate how to reduce the cluster's reliance on a single API, including alternatives to hetzner-k3s
    • Document and test a procedure for recovering Longhorn after a full cluster shutdown
    Lessons

    The running cluster, not only the deployment tooling, consumed the cloud provider's API quota, and in a failure it consumed it fast enough that the quota never recovered. The default limit of 3600 requests per hour was not enough for failure and recovery scenarios, and API usage from inside the cluster was not monitored. A tool that hides the provider's API errors slows diagnosis. After a full, non-graceful shutdown, Longhorn needed manual intervention to come back, which lengthened the outage.

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Check your cluster for this

This case involves Cloud controller manager and Persistent volumes and stateful sets. kubegap audits a Kubernetes cluster for gaps like these, read-only, from Claude Code or Codex; its checks cite public reports like the ones in this library.

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By root cause1

Capacity exhaustion1 case

Component
Cloud controller managerPersistent volumes and stateful sets
Contributing factor
Unknown limitLimited debug accessMonitoring blind spotNo runbookRetry stormSingle point of failure
Organisation
Magic Pages
  1. IL-0085 A control plane node of Magic Pages' Kubernetes cluster on Hetzner Cloud ran out of memory, the cluster's own calls then used up the Hetzner API rate limit, and all customer websites were down for about 7.5 hours
    Magic Pages2025