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Klag Klag

Build from Source

Klag is a Java 21 / Vert.x project built with Gradle.

Requirements

Section titled “Requirements”
  • Java 21 (use SDKMAN if needed: sdk use java 21.0.9-tem).
  • Use ./gradlew locally; CI uses gradle directly (no wrapper JAR committed).

Common tasks

Section titled “Common tasks”
Terminal window
./gradlew compileJava   # Compile
./gradlew test          # Run tests
./gradlew assemble      # Package (fat JAR)
./gradlew run           # Run with hot-reload

Helm chart template tests

Section titled “Helm chart template tests”

Fast and offline. Lints the chart and renders every values permutation:

Terminal window
./scripts/test-helm-chart.sh

End-to-end tests (k3d + real Kafka)

Section titled “End-to-end tests (k3d + real Kafka)”

The canonical integration test spins up a disposable k3d cluster, deploys a real single-node KRaft Kafka, builds the Klag image from the local Dockerfile, installs the Helm chart, generates real lag, and asserts Klag exposes it via /metrics. Nothing is mocked.

Terminal window
./scripts/e2e-test.sh                 # Full e2e + cleanup
./scripts/e2e-test.sh --auto-install  # Install k3d/kubectl/helm via Homebrew
./scripts/e2e-test.sh --skip-cleanup  # Keep the cluster for inspection
KLAG_IMAGE=themoah/klag:0.1.12 ./scripts/e2e-test.sh   # Test a published image
KAFKA_IMAGE=apache/kafka:3.7.0 ./scripts/e2e-test.sh   # Test an older broker
./scripts/e2e-test.sh --cleanup       # Delete the test cluster

Strimzi compatibility tests

Section titled “Strimzi compatibility tests”

See Strimzi:

Terminal window
./scripts/e2e-strimzi-test.sh
KAFKA_VERSION=4.1.0 ./scripts/e2e-strimzi-test.sh
./scripts/e2e-strimzi-matrix.sh 4.1.0 4.2.0

Prerequisites: Docker, k3d, helm, kubectl (--auto-install installs via Homebrew). Both e2e suites run in CI on every PR (.github/workflows/e2e.yml).

Native image

Section titled “Native image”

See Native Image for the GraalVM build.