k8s-certs

k8s-certs is a skill for Claude Code, Codex from yindia/rootcause. It costs 0 tokens per session (1,603 once invoked), scanned A, original, MIT.

A guide for diagnosing cert-manager, a Kubernetes component that obtains and renews TLS certificates for encrypted connections. It follows certificates from the request and issuer through to the secret used by an ingress.

In plain words
What is it for?
Investigating missing or expired certificates, failed Let's Encrypt challenges, unavailable issuers, missing TLS secrets, and certificate handshake errors.
Why use it?
It helps locate where certificate issuance, renewal, storage, or ingress TLS integration has failed.

Skill for Claude CodeCodex

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

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.

agentmods
npx agentmods add skills/yindia/rootcause/k8s-certs
Any agent
npx skills add yindia/rootcause --skill k8s-certs
Clone the repo
git clone --depth 1 https://github.com/yindia/rootcause

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 k8s-certs

README.md
[![agentmods](https://agentmods.dev/badge/skills/yindia/rootcause/k8s-certs.svg)](https://agentmods.dev/skills/yindia/rootcause/k8s-certs)
Your own site
<a href="https://agentmods.dev/skills/yindia/rootcause/k8s-certs"><img src="https://agentmods.dev/badge/skills/yindia/rootcause/k8s-certs.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,603 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00000 $0.01603
Opus 5 $0.00000 $0.00801
Sonnet 5 $0.00000 $0.00321
Haiku 4.5 $0.00000 $0.00160

Measured 6d ago against content hash 575749b9eab6, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

k8s-certs 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 6d 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/claude/k8s-certs/SKILL.md · 269 lines

How it starts

The opening of the file, as written. The whole thing — 269 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill: k8s-certs

Comprehensive cert-manager diagnostics for certificate lifecycle, issuer health, renewal failures, and ingress TLS integration.

Trigger Phrases

Use this skill when the user mentions:

  • cert-manager broken
  • certificate not ready
  • tls secret missing
  • x509 expired or unknown authority
  • renewal failed
  • letsencrypt challenge failed
  • clusterissuer not ready
  • ingress tls handshake error
  • certificate request stuck

RootCause Tools Allowed

Only use these tool names in this skill:

  • k8s.cert_manager_detect
  • k8s.diagnose_cert_manager
  • k8s.describe
  • k8s.list
  • k8s.events
  • k8s.events_timeline

Cert-Manager Workflow Overview

Canonical path:

  1. detect installation
  2. diagnose control-plane and resource status
  3. inspect failing certificate and issuer
  4. validate event timeline for renewal attempt
  5. map to ingress/secret consumption impact

Certificate Lifecycle Reference

Lifecycle checkpoints:

  1. Certificate resource created.
  2. CertificateRequest generated.
  3. Issuer signs request.
  4. Secret populated/updated.
  5. Workloads consume updated secret.
  6. Renewal happens before expiry window.

Common lifecycle states:

  • Ready true
  • Ready false (temporary)
  • Ready false (terminal misconfig)

Issuer Types

Let's Encrypt (ACME)

Typical dependencies:

  • valid account registration
  • challenge solver (HTTP-01 or DNS-01)
  • ingress/dns routing correctness

Failure hotspots:

  • challenge path not reachable
  • DNS mismatch for hostname
  • rate limits from ACME provider

Self-signed

Use cases:

  • internal service encryption
  • development/test clusters

Failure hotspots:

  • trust chain not distributed to clients
  • accidental production usage without trust setup

CA-backed internal issuer

Use cases:

  • private PKI integration
  • enterprise trust chains

Failure hotspots:

  • missing or invalid CA secret
  • expired intermediate CA

Detection and Baseline

Step 1: Confirm cert-manager footprint

Use k8s.cert_manager_detect first.

Read the full file on GitHub · 269 lines

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. 6d ago First seen · 269 lines · 0 tokens per session scan A 575749b9eab6

Subscribe to this mod's changes

k8s-certs is a skill published in the GitHub repository yindia/rootcause (42 stars, last pushed 3mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,603 tokens. 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.