Cases2 cases

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1. IL-0162 LKE users could not reach their cluster control planes or the LKE Dashboard because an earlier database update made the internal LKE DNS service hang

   Linode2025

   Symptoms

   On 1 April 2025 users of Linode Kubernetes Engine (LKE) began having trouble connecting to their clusters' control planes, and the LKE Dashboard was affected as well. Services inside the clusters kept working. The first status update was posted at 20:28 UTC; at 21:33 UTC Linode said it was investigating an issue with DNS functionality within LKE.

   DNS resolution failuresControl plane unresponsive

   Trigger

   An earlier update to a database that the LKE DNS system depends on caused the DNS service to hang.

   Root cause

   Dependency failure

   Component

   Authoritative DNS servers and recordsApplication database

   Contributing factor

   –

   Detection

   The first status update, at 20:28 UTC on 1 April, said Linode was investigating and that users might have difficulty connecting to their cluster control plane. At 21:33 UTC Linode said the issue affected DNS functionality within LKE, and at 22:29 UTC that it had identified the underlying cause.

   Remediation

   • restarted the affected LKE DNS services

   Action items

   • Improve how the DNS services recover from transient connectivity failures to their dependencies
   • Improve monitoring to detect similar problems sooner
   • Update the deployment process to better coordinate changes between dependent systems

   Lessons

   A change to a database that the DNS service depends on can make the DNS service hang, which here cut off external access to the clusters and the LKE Dashboard while services inside the clusters kept working. The DNS service should recover by itself from transient failures of its dependencies, and changes to dependent systems need to be coordinated.

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2. IL-0159 Docker Hub rate-limited Linode's IPv6 address space with 429 Too Many Requests, breaking image pulls for LKE and LKE-E clusters

   Linode2025

   Symptoms

   From about 21:38 UTC on 5 February 2025, image pulls from Docker Hub over IPv6 failed with 429 Too Many Requests errors across several Linode regions. Both unauthenticated and authenticated pull requests were refused.

   Image pull failures

   Trigger

   Docker Hub's abuse prevention measures started rate-limiting image pulls coming from Linode's IPv6 address space.

   Root cause

   Dependency failure

   Component

   Container registry and its credentialsVPC DNS resolver

   Contributing factor

   Unknown limit

   Detection

   The rate limiting began at about 21:38 UTC. The first status post, at 22:48 UTC, said Linode was aware of an issue with Docker Hub over IPv6 causing rate limiting and was investigating, and at 01:06 UTC on 6 February the status page said the issue had been identified as rate limiting of image pull requests to Docker Hub over IPv6.

   Remediation

   • changed the DNS resolvers to return an A record instead of an AAAA record so image pulls to Docker Hub used IPv4

   Action items

   • Find long-term solutions so that Docker Hub's abuse prevention measures do not affect Linode services

   Lessons

   A registry's abuse limit that groups IPv6 addresses by their first 64 bits can block a provider's whole address range at once, and authentication does not help. Answering DNS lookups with IPv4 addresses only was the quick way to move image pulls off the blocked range.

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