Incident Library
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Cases2 cases

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  1. IL-0283 Cloudflare's core proxy returned HTTP 5xx across its network after loading an oversized Bot Management feature file
    Cloudflare2025
    Symptoms

    From about 11:20 UTC on 18 November 2025, Cloudflare's network started failing to deliver core traffic, and Internet users visiting Cloudflare customers' sites got an error page that pointed to a failure inside Cloudflare's network. The volume of HTTP 5xx responses served by the network jumped far above its normal low baseline.

    High error rateService outageHigh latencyResponse quality degradation
    Trigger

    At 11:05 UTC Cloudflare deployed a ClickHouse access control change that made users' existing implicit access to the underlying tables in the r0 database explicit, so the metadata of those tables became visible in system tables such as system.columns. The change was being rolled out gradually across the cluster.

    Root cause
    Configuration change
    Component
    DatabaseCDN and edge network
    Contributing factor
    Unverified assumptionPartial rolloutNo staged rolloutNo configuration testsOverlapping failuresRetry storm
    Detection

    The first automated test detected the issue at 11:31 UTC, three minutes after the first errors on customer HTTP traffic at 11:28. Manual investigation started at 11:32 and the incident call was created at 11:35.

    Remediation
    • Bypassed the core proxy for Workers KV and Access so they fell back to a prior proxy version, which reduced their impact
    • Stopped the automatic creation and deployment of new Bot Management feature files
    • Inserted a known good feature file into the distribution queue and deployed it globally
    • Forced a restart of the core proxy
    • Scaled control plane concurrency to clear the backlog of dashboard logins
    • Restarted the remaining services that had entered a bad state
    Action items
    • Harden the ingestion of Cloudflare-generated configuration files the same way as user-generated input
    • Enable more global kill switches for features
    • Stop core dumps and other error reports from being able to overwhelm system resources
    • Review the failure modes for error conditions across all core proxy modules
    View case
  2. IL-0522 An ingress-nginx chart upgrade deleted the jenkins.io Ingress and Fastly served HTTP/503 errors for hours
    Jenkins project2021
    Symptoms

    At 11:32 UTC on 18 November 2021, a user reported in the jenkinsci/jenkins Gitter channel that https://www.jenkins.io/doc/pipeline/steps/ was answering HTTP/503 errors with the message "Guru meditation" from Fastly's varnish.

    Service outageResources deleted
    Trigger

    The ingress-nginx Helm chart was upgraded from 4.0.6 to 4.0.8 at 10:42 UTC, and the new chart added an admission webhook rule that forbids Nginx configuration blocks in Ingress annotations.

    Root cause
    Breaking change in an upgrade
    Component
    Ingress controllerAdmission webhookHelmCDN and edge network
    Contributing factor
    Unverified assumptionCache-masked failureMonitoring blind spotHarmful manual action
    Detection

    A user reported in the jenkinsci/jenkins Gitter channel at 11:32 UTC that a jenkins.io page answered HTTP/503 errors, and status.jenkins.io reported the incident at 11:49 UTC.

    Remediation
    • Disabled the automated systems, rolled the ingress-nginx chart back to 4.0.6 and deleted the admission webhook by hand
    • Removed the forbidden annotations from the jenkins.io configuration
    • Upgraded the jenkins.io Helm chart to the last version known to work with ingress-nginx 4.0.8
    • Redeployed the jenkins.io Helm chart through the automated system and told Fastly to drop all cached pages
    Action items
    • Always read the changelog in depth when updating the ingress controllers, with two people pairing in real time
    • Add custom Datadog monitoring for www.origin.jenkins.io so that such an outage is detected
    • Make the monitor send the Host header www.jenkins.io so it is not redirected to Fastly
    • Check a set of pages, such as the pipeline steps page, not only the front page
    • Consider an ephemeral k3s end-to-end test before deploying to production
    Lessons

    Trusting a patch version of a Helm chart for the Ingress controller without reading its changelog in depth let a new admission rule remove the jenkins.io Ingress in production. Without monitoring on origin.jenkins.io, a user found the outage. A complete staging cluster with the same DNS setup would have caught the problem before production.

    View case
Check your cluster for this

These 2 cases involve CDN and edge network 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 cause2

Configuration change1 case

Component
CDN and edge networkDatabase
Contributing factor
Unverified assumptionNo configuration testsNo staged rolloutOverlapping failuresPartial rolloutRetry storm
Organisation
Cloudflare
  1. IL-0283 Cloudflare's core proxy returned HTTP 5xx across its network after loading an oversized Bot Management feature file
    Cloudflare2025

Breaking change in an upgrade1 case

Component
Admission webhookCDN and edge networkHelmIngress controller
Contributing factor
Unverified assumptionCache-masked failureHarmful manual actionMonitoring blind spot
Organisation
Jenkins project
  1. IL-0522 An ingress-nginx chart upgrade deleted the jenkins.io Ingress and Fastly served HTTP/503 errors for hours
    Jenkins project2021