Triage Kubernetes Service DNS

Triage Kubernetes Service DNS is a skill for Claude Code, Codex from bregman-arie/devops-sre-skills. It costs 19 tokens per session (508 once invoked), scanned A, original, Apache-2.0.

A troubleshooting procedure for finding the cause of DNS failures inside Kubernetes, a system for running applications in containers.

In plain words
What is it for?
It helps test service and external names, inspect pod resolver settings, compare results across pods and nodes, review CoreDNS logs, and verify a fix.
Why use it?
It narrows down whether name-resolution problems come from a pod, namespace, node, network policy, or CoreDNS, the Kubernetes DNS service.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit It helps test service and external names, inspect pod resolver settings, compare results across pods and nodes, review CoreDNS logs, and verify a fix.

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Install with agentmods
npx agentmods add skills/bregman-arie/devops-sre-skills/triage-service-dns
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add bregman-arie/devops-sre-skills --skill triage-service-dns
Clone the repo
git clone --depth 1 https://github.com/bregman-arie/devops-sre-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for Triage Kubernetes Service DNS

README.md
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Your own site
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Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for Triage Kubernetes Service DNS

Your own site · 80×15
<a href="https://agentmods.dev/skills/bregman-arie/devops-sre-skills/triage-service-dns"><img src="https://agentmods.dev/badge/skills/bregman-arie/devops-sre-skills/triage-service-dns.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 19 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 508 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00019 $0.00508
Opus 5 $0.00010 $0.00254
Sonnet 5 $0.00004 $0.00102
Haiku 4.5 $0.00002 $0.00051

Measured 12d ago against content hash 379d2f65c4dd, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

Triage Kubernetes Service DNS scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/kubernetes/triage-service-dns/SKILL.md · 72 lines

What it actually says

When to use

Use when pods cannot resolve service names (e.g., *.svc.cluster.local) or external DNS intermittently fails.

Preconditions

  • You can run commands in a diagnostic pod or an affected pod.
  • You can access CoreDNS/kube-dns logs.

Procedure

  1. Confirm whether the issue is cluster-wide or namespace/workload-specific.
  2. Validate resolver configuration inside the pod (/etc/resolv.conf) and search domains.
  3. Query the same name from multiple pods/nodes to identify locality.
  4. Check CoreDNS health, restarts, and error logs.
  5. Check network policies and CNI health that might block DNS to the DNS service.

Decision points

  • Only one namespace affected: network policy or custom DNS config.
  • Only one node affected: node-level networking issues.
  • CoreDNS errors/timeouts: capacity, upstream recursion, or misconfiguration.
  • NXDOMAIN for a service: confirm the service/endpoints exist.

Verification

  • Repeated DNS queries succeed from multiple pods.
  • CoreDNS error logs stop increasing.

Rollback / undo

  • Revert CoreDNS config changes.
  • Revert network policy changes if they widen access unexpectedly.

Escalation

  • Platform/network team for CNI or node-level packet loss.
  • Service owner if the service/endpoints are missing due to deploy issues.

Examples

kubectl -n <ns> exec <pod> -- cat /etc/resolv.conf
kubectl -n <ns> exec <pod> -- nslookup <service>.<ns>.svc.cluster.local
kubectl -n kube-system logs -l k8s-app=kube-dns --tail=200
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 12d ago First seen · 72 lines · 19 tokens per session scan A 379d2f65c4dd

Subscribe to this mod's changes

Triage Kubernetes Service DNS is a skill published in the GitHub repository bregman-arie/devops-sre-skills (22 stars, last pushed 5mo ago), licensed Apache-2.0. It adds 19 tokens to every session and 508 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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