Cases2 cases

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1. IL-0234 An onboarding operator deployed without its scope file installed dev applications on other IONOS Kubernetes clusters

   IONOS Cloud2026

   Symptoms

   On 8 May 2026 IONOS Cloud reported "K8s Control Planes not available": some Managed Kubernetes customers in DE/TXL, DE/FRA and DE/FRA/2 had trouble connecting to the control plane and saw degraded Kubernetes functionality. Between 15:22 and 16:12 (UTC+2) applications meant for a new internal development cluster were installed on other customer clusters, which were also modified.

   Control plane unresponsiveImage pull failures

   Trigger

   A routine internal operation onboarded a new Managed Kubernetes development cluster. The scoping configuration file for the onboarding operator failed to reach the deployment branch because of a merge conflict, and at the same time a second change removed the operator from the exclusion list, which deployed it at once.

   Root cause

   Faulty deployment

   Component

   CI systemContainer registry and its credentials

   Contributing factor

   No configuration testsExcessive blast radiusMissed in review

   Remediation

   • Corrected the onboarding operator so it needs an explicit namespace configuration before acting on any cluster
   • Reconfigured the deployment system to fail deployments when required configuration files are missing
   • Rolled back the identified changes on the affected resources
   • Ran a recovery script, validated in staging, that removed all unintended installations and updates from the affected clusters

   Action items

   • Add a mandatory CI/CD step that confirms all required configuration files reached the target branch before any deployment starts
   • Require additional peer review and change management approval for every deployment that touches production, whatever its size
   • Give teams a way to inform each affected customer in time about the status of post-incident cleanup

   Lessons

   IONOS treats the unintended change to cluster configurations as a failure of the controls that should keep internal operations from affecting customer environments.

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2. IL-0464 IONOS Managed Kubernetes control planes went unreachable for minutes at a time as their shared etcd grew and fragmented

   IONOS Cloud2026

   Symptoms

   From 14 to 16 March 2026 a subset of customer control planes on IONOS Managed Kubernetes (MK8s) became unavailable again and again, each time for several minutes. While a cluster was unreachable, operations that depend on the Kubernetes API, such as deployments, scaling and health checks, did not work reliably.

   Control plane unresponsiveImage pull failures

   Root cause

   Capacity exhaustion

   Component

   etcdKubernetes API serverManaged Kubernetes control plane and provider API

   Contributing factor

   Excessive blast radius

   Remediation

   • Defragmented the affected database instances, reclaiming about 3–4 GiB per instance
   • Shortened the database compaction intervals on the affected instances
   • Deployed a fix for the affected AI Model Hub database services
   • Applied final changes to all affected clusters

   Action items

   • Expand monitoring dashboards to show control plane health per database instance
   • Move the highest-volume clusters to dedicated database backends
   • Make incidents of this kind trigger immediate paging
   • Roll the updated compaction interval out to all shared control plane database instances
   • Run automated, scheduled defragmentation jobs on all instances
   • Rebalance clusters across database instances to reduce concentration
   • Contact customers whose clusters write disproportionate data, for example to store large security scan reports outside the control plane database
   • Introduce per-tenant resource quotas and key-count limits on the shared control plane database
   • Re-architect the shared control plane for stronger isolation, with dedicated database instances and better vertical scaling
   • Evaluate full database sharding for customers with consistently high data volumes
   • Hold regular drills on database resource exhaustion and recovery

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