SBD Operator

A Kubernetes operator for managing STONITH Block Device (SBD) configurations and remediations for high-availability clustering. The operator provides automated node remediation when nodes become unresponsive by leveraging shared block storage for fencing operations.

Overview

The SBD operator implements a cloud-native approach to Storage-Based Death (SBD) for Kubernetes environments where traditional out-of-band management (IPMI, iDRAC) is unavailable. It uses shared block storage to provide reliable node fencing capabilities, ensuring data consistency and preventing split-brain scenarios in stateful workloads.

Architecture

The operator consists of two main components:

• SBD Operator: Manages SBDConfig and SBDRemediation custom resources and deploys the SBD agent
• SBD Agent: Runs as a DaemonSet on cluster nodes, handling local watchdog operations and shared storage communication

Key Features

• Shared Storage Fencing: Uses CSI block PVs with concurrent multi-node access for inter-node communication
• Dual Watchdog System: Combines shared storage watchdog with local kernel watchdog for robust failure detection
• Kubernetes Integration: Native CRDs for configuration management and remediation requests
• Prometheus Metrics: Built-in monitoring and observability
• Split-Brain Prevention: Shared storage arbitration ensures cluster consistency

Custom Resources

SBDConfig

Defines the SBD configuration for the cluster:

• Shared block device PVC name
• Timeout settings
• Watchdog device path
• Node exclusion lists
• Reboot methods

SBDRemediation

Triggers node remediation operations:

• Target node specification
• Remediation status tracking
• Integration with Medik8s Node Healthcheck Operator

Quick Start

Prerequisites

• Kubernetes cluster with CSI driver supporting volumeMode: Block
• Shared block storage with concurrent multi-node access (e.g., Ceph RBD, cloud provider shared volumes)
• Cluster nodes with kernel watchdog support

Installation

1. Install the operator:

make deploy

2. Create an SBDConfig:

kubectl apply -f config/samples/medik8s_v1alpha1_sbdconfig.yaml

Development

Build and test locally:

# Build the operator
make build

# Run tests
make test

# Run e2e tests
make test-e2e

# Build and push images
make docker-build docker-push IMG=<your-registry>/sbd-operator:tag

Documentation

Comprehensive documentation is available in the docs/ directory:

• Design Document - Architecture and design principles
• Blueprint - Detailed implementation blueprint
• User Guide - Configuration and usage
• Webhook Requirements - Admission webhook setup

Testing

The project includes comprehensive testing:

• Unit Tests: make test
• E2E Tests: make test-e2e
• Smoke Tests: make test-smoke

E2E tests deploy a complete operator environment and verify functionality end-to-end.

Contributing

1. Follow Go best practices and project coding standards
2. Include comprehensive tests for new features
3. Update documentation for user-facing changes
4. Ensure all tests pass before submitting PRs

Requirements

• Go 1.21+
• Kubernetes 1.28+
• Docker/Podman for container builds
• Make for build automation

License

Licensed under the Apache License 2.0. See LICENSE for details.

Support

For issues, questions, or contributions, please use the GitHub issue tracker.