What is klag CLAUDE.md?

A project guide for Klag, a Java service that monitors Kafka consumer lag and exports metrics. It documents build, test, end-to-end testing, and GraalVM native-binary commands.

Use it when developing, testing, packaging, or creating a native executable for Klag.

It gives coding agents the project's architecture, required Java setup, and standard commands for building and validating changes.

How themoah/klag configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to themoah/klag. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/themoah/klag/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/themoah/klag

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/themoah/klag/claude-md/github.svg)](https://agentmods.dev/instructions/themoah/klag/claude-md)

Your own site

<a href="https://agentmods.dev/instructions/themoah/klag/claude-md"><img src="https://agentmods.dev/badge/instructions/themoah/klag/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>

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.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/themoah/klag/claude-md"><img src="https://agentmods.dev/badge/instructions/themoah/klag/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 6,612 This file is loaded in full into every session.

When invoked 6,612 The same file — it is already loaded in full.

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.

Model	Per session	Once invoked
Fable 5.1	$0.06612	$0.06612
Opus 5.5	$0.02645	$0.02645
Sonnet 5.5	$0.01322	$0.01322
Haiku 4.5	$0.00661	$0.00661

Measured 16d ago against content hash 8b7c87b9bd61, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

klag CLAUDE.md 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 16d 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.

CLAUDE.md · 338 lines

How it starts

The opening of the file, as written. The whole thing — 338 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

Project Overview

Klag is a Kafka Lag Exporter built with Vert.x 4.5.34. Monitors consumer lag and group states with Prometheus/Datadog/OTLP/StatsD metrics.

Build Commands

# Requires Java 21 - use SDKMAN if needed: sdk use java 21.0.9-tem
# Local: use ./gradlew | CI: uses gradle directly (no wrapper JAR committed)

./gradlew compileJava          # Compile
./gradlew test                 # Run tests
./gradlew assemble             # Package (creates fat JAR)
./gradlew run                  # Run with hot-reload

./scripts/test-helm-chart.sh   # Helm chart template tests (offline)
./scripts/e2e-test.sh          # Full e2e: k3d + real Kafka + chart + lag asserts
./scripts/e2e-strimzi-test.sh  # e2e against Strimzi-operator-managed Kafka (KRaft)
./scripts/e2e-strimzi-matrix.sh # Strimzi e2e across supported Kafka versions

GraalVM Native Image (startup/memory optimized)

Requires a GraalVM JDK 21 (LTS) with native-image (e.g. sdk install java 21.0.2-graalce). Run Gradle with that JDK as JAVA_HOME/GRAALVM_HOME.

gradle nativeCompile           # -> build/native/nativeCompile/klag (standalone binary)
docker build -f Dockerfile.native -t klag:native .   # distroless runtime image
scripts/benchmark-startup.sh native - build/native/nativeCompile/klag  # startup/RSS bench

Native config lives in build.gradle.kts (graalvmNative block) plus reachability hints in src/main/resources/META-INF/native-image/. Reflection metadata for Netty, kafka-clients, logback and micrometer comes from the GraalVM Reachability Metadata Repository (auto-enabled). Entry point is KlagLauncher (direct new MainVerticle(), no reflective Vert.x launcher).

Measured (macOS arm64, prometheus reporter, Kafka up): native ≈ 70-100 ms startup / 44 MB RSS vs JVM 21 ≈ 470-520 ms / 119 MB. JVM 25 (LTS) showed no startup/memory gain over 21 for this workload (slightly higher RSS), so the runtime stays on JDK 21.

Architecture

Vert.x reactive framework with Future<T>-based async API.

Read the full file on GitHub · 338 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.

16d ago Changed · +28 tokens per session 8b7c87b9bd61
24d ago Changed · +7 lines · +241 tokens per session c4533f55c84a
1mo ago Changed · +227 tokens per session 3e201915a1df
1mo ago Changed · +12 lines · +162 tokens per session 22c37f910f6e
2mo ago Changed · +33 lines · +780 tokens per session 1550b10b210d
2mo ago First seen · 286 lines · 5,174 tokens per session scan A bfb569197f7d

Subscribe to this mod's changes

klag CLAUDE.md is an instructions file published in the GitHub repository themoah/klag (88 stars, last pushed 5d ago), licensed Apache-2.0. It adds 6,612 tokens to every session, about $0.0264 per session on Opus 5.5. 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.

Analytics and metrics Backend and APIs hacktoberfest kafka kafka-consumer monitoring

klag CLAUDE.md next to 6 instructions from other repositories
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klag: Instructions file for Claude Code