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Cases2 cases

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  1. IL-0152 An incorrect configuration applied during maintenance made an internal infrastructure cluster automatically delete the control planes of 200 DOKS clusters in FRA1
    DigitalOcean2024
    Symptoms

    At 13:02 UTC on 2024-01-23 DigitalOcean posted that, as of 12:18 UTC, its engineers were investigating an issue with Kubernetes clusters in the FRA1 region and that users might see errors when communicating with their clusters. The control planes of the affected DOKS (DigitalOcean Kubernetes) clusters had become inaccessible.

    Resources deletedControl plane unresponsive
    Trigger

    An incorrect configuration was applied to an internal infrastructure cluster in FRA1 at 12:21 UTC during a maintenance operation.

    Root cause
    Configuration change
    Component
    etcdKubernetes API server
    Contributing factor
    Automation amplificationNo safeguard on destructive changeExcessive blast radius
    Detection

    Engineers were investigating errors with Kubernetes clusters in FRA1 as of 12:18 UTC and identified the incorrect configuration as the cause at 12:36.

    Remediation
    • restored each affected cluster's etcd from its latest twice-daily backup
    • restored the stateless control plane components after etcd
    • patched the recovery mechanism after unexpected problems during recovery
    • found and fixed an additional small bug during recovery
    • contacted affected customers directly with further instructions, since some might need to reconfigure Kubernetes resources
    Action items
    • Prevent automatic deletion of infrastructure cluster resources under any circumstances in the production environment
    Lessons

    When managed control planes run as resources in another cluster, one configuration mistake in that cluster can delete hundreds of control planes at once through ordinary automation. The etcd backups limited the damage, but their twice-daily schedule set the worst case at 12 hours of lost control plane state, and the recovery tooling itself needed patching during the incident.

    View case
  2. IL-0008 An unresponsive OPA validating webhook crash-looped the API server during a GKE master upgrade, and node auto-repair then recreated every node
    Jetstack2019
    Symptoms

    Jetstack was upgrading the master of a development cluster that many teams use to test their apps during the working day, a regional Google Kubernetes Engine (GKE) cluster in europe-west1. The upgrade ran through Jetstack's GKE Terraform pipeline and did not finish before the 20-minute Terraform timeout, while the GKE console still showed the cluster as upgrading.

    Upgrade stallControl plane unresponsiveNode recreation loopService outage
    Trigger

    A planned master upgrade of the shared development cluster. The same upgrade had been done on another pre-production environment earlier that day, and no API downtime was expected.

    Root cause
    Configuration change
    Component
    Admission webhookGKE control planeKubernetes API serverkubelet
    Contributing factor
    Excessive blast radiusNo health probesMonitoring blind spotAutomation amplification
    Detection

    The first sign was the master upgrade missing the 20-minute Terraform timeout; re-running the pipeline returned the kube-apiserver unhealthy error. The cause was identified with the help of Google Support.

    Remediation
    • Deleted the OPA ValidatingAdmissionWebhook resource during a window of API server access
    Action items
    • Limit the OPA webhook to the namespaces where the policy applies and development teams have access
    • Enable the webhook only for Ingress and Service resources, the only resources the policy validates
    • Add a liveness probe so OPA is restarted when it stops responding, and update the OPA documentation
    • Follow the open upstream Kubernetes issue about this behaviour
    Lessons

    With alerting on API server response times, the team might have seen CREATE and UPDATE requests slow down across the board as soon as the OPA-backed webhook was first deployed. Every workload needs probes: OPA looked so simple to deploy that the team skipped the Helm chart, which adds a livenessProbe for the admission controller containers among other adjustments to the tutorial configuration. Others had hit the same problem, and an upstream issue to improve it was still open.

    View case
Check your cluster for this

These 2 cases involve Kubernetes API server and Admission webhook. 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

Configuration change2 cases

Component
Kubernetes API server2Admission webhook1etcd1GKE control plane1kubelet1
Contributing factor
Automation amplification2Excessive blast radius2Monitoring blind spot1No health probes1No safeguard on destructive change1
Organisation
DigitalOcean1Jetstack1
  1. IL-0152 An incorrect configuration applied during maintenance made an internal infrastructure cluster automatically delete the control planes of 200 DOKS clusters in FRA1
    DigitalOcean2024
  2. IL-0008 An unresponsive OPA validating webhook crash-looped the API server during a GKE master upgrade, and node auto-repair then recreated every node
    Jetstack2019