Test Overlay Network of your Kubernetes Cluster

This is a Go client of the Overlay Network Test, a shell script paired with a DaemonSet to check connectivity in Overlay Network in Kubernetes Cluster.

• kube-config with connection to a working Kubernetes Cluster
• access kube-system namespace where the application will deploy (needs privileged mode for network ping command)

Download artifact from Release Page and execute:

# Basic usage
./overlaytest

# Show version
./overlaytest -version

# Reuse existing deployment
./overlaytest -reuse

# Custom kubeconfig
./overlaytest -kubeconfig /path/to/kubeconfig

The application version can be configured in multiple ways (priority order):

1. Environment variable (runtime):

   APP_VERSION=1.0.7 ./overlaytest -version

2. Build-time ldflags (compile time):

   go build -ldflags "-X github.com/eumel8/overlaytest/pkg/overlaytest.Version=1.0.7" -o overlaytest ./cmd/overlaytest

3. Default version: Falls back to hardcoded version (1.0.6)

The project follows standard Go layout:

overlaytest/
├── cmd/overlaytest/          # Main application entry point
│   └── main.go
├── pkg/overlaytest/          # Library code
│   ├── version.go           # Version management
│   ├── config.go            # Configuration handling
│   ├── client.go            # Kubernetes client setup
│   ├── daemonset.go         # DaemonSet management
│   ├── network.go           # Network testing logic
│   └── *_test.go            # Unit tests
├── Dockerfile               # Container image definition
└── .github/workflows/       # CI/CD pipelines

Current Image: ghcr.io/eumel8/overlaytest:latest

The project includes a minimal Alpine-based container image (~10MB compressed) with:

• bash shell
• ping command
• Non-root user (UID 1000)

docker build -t overlaytest:local .
docker run --rm overlaytest:local ping -c 2 8.8.8.8

You can specify a custom container image:

config := overlaytest.DefaultConfig()
config.Image = "your-registry/your-image:tag"

Previous Image (deprecated): mtr.devops.telekom.de/mcsps/swiss-army-knife:latest

• source
• repo

The DaemonSet includes comprehensive security context configuration:

• ✅ Privileged mode: Required for ping operations
• ✅ Non-root user: Runs as UID/GID 1000
• ✅ Read-only root filesystem: Enhanced security
• ✅ Seccomp profile: RuntimeDefault (Kubernetes security standard)
• ✅ Resource limits: CPU (100m-200m), Memory (64Mi-128Mi)

• ✅ Kyverno policies: Meets resource and seccomp requirements
• ✅ Pod Security Standards: Compatible with restricted policies (except privileged requirement)
• ✅ Issue #179: All requirements addressed

• Go 1.25 or later
• Docker (for container image builds)

# Clone the repository
git clone https://github.com/eumel8/overlaytest.git
cd overlaytest

# Build with default version
go build -o overlaytest ./cmd/overlaytest

# Build with custom version
go build -ldflags "-X github.com/eumel8/overlaytest/pkg/overlaytest.Version=1.0.7" \
  -o overlaytest ./cmd/overlaytest

# Run tests
go test -v ./...

# Build for multiple architectures
docker buildx build --platform linux/amd64,linux/arm64 \
  -t ghcr.io/eumel8/overlaytest:latest .

# Build and push (requires authentication)
docker buildx build --platform linux/amd64,linux/arm64 \
  -t ghcr.io/eumel8/overlaytest:latest --push .

The project includes automated GitHub Actions workflows:

• release.yaml: Builds multi-platform binaries on release
• docker-build.yaml: Builds and pushes container images
• e2e-test.yaml: End-to-end tests with Kind clusters
• coverage.yaml: Code coverage reporting

# Run all tests
go test ./...

# Run with coverage
go test -cover ./...

# Run specific package tests
go test -v ./pkg/overlaytest/

• cmd/overlaytest/: Main application entry point
• pkg/overlaytest/: Reusable library code
• Dockerfile: Container image definition
• .github/workflows/: CI/CD automation

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Make your changes with tests
4. Run go test ./... to verify
5. Submit a pull request

Frank Kloeker f.kloeker@telekom.de

Life is for sharing. If you have an issue with the code or want to improve it, feel free to open an issue or an pull request.