k8s-coredns-troubleshooting

Use when cluster DNS itself misbehaves on Kubernetes: CoreDNS pods in CrashLoopBackOff ("Error during parsing: Unknown directive", "plugin/loop: Loop ... detected"), "reload failed" after a Corefile edit, external names failing while Service names resolve (";; connection timed out; no servers could be reached", SERVFAIL, "plugin/errors: 2 ... i/o timeout"), one domain or stub domain failing, rewrite or hosts entries that do not work, "Plugins not ready: \"kubernetes\"", REFUSED or "concurrent queries exceeded maximum", slow lookups (ndots, 5 s delays), NodeLocal DNSCache (169.254.20.10), or the AKS coredns-custom, EKS add-on and GKE kube-dns ConfigMaps. Investigates with kubectl get and logs, and proposes fixes. Reads first and asks before changing anything.

License

Apache-2.0