Why High Availability Matters
A high-availability deployment ensures:- No single point of failure
- Redundant services distributed across zones or regions
- Automated failover and recovery
- Increased uptime for business-critical use cases
Key HA Components
Kubernetes Cluster Architecture
Kubernetes Cluster Architecture
- Use multi-zone clusters: Spread nodes across at least 2 availability zones.
- Control Plane Resilience: Managed Kubernetes services like EKS, GKE, AKS provide HA for control planes by default.
- Auto-scaling enabled: Ensure node groups scale with demand to avoid overloads.
Microservice Redundancy
Microservice Redundancy
- Replicas: Deploy multiple replicas of core services:
- API Gateway: 2+
- Runtime: 3+
- Console/Studio: 2+
- Pages: 2+
- Use Kubernetes Deployments with readiness and liveness probes.
Load Balancing & Ingress
Load Balancing & Ingress
- Ingress controllers: Use cloud-native ingress controllers (e.g., ALB, NGINX, Istio) with health checks and retries.
- DNS: Configure DNS to route traffic across healthy zones (e.g., Route 53 with latency-based routing).
Stateless vs Stateful Services
Stateless vs Stateful Services
- Stateless services (API, Console, Pages, Runtime) should be scaled freely.
- Stateful services (MongoDB, Redis, Elasticsearch) must use clustered, HA configurations with persistent storage.
Storage Availability
Storage Availability
- Use replicated storage backends like:
- AWS EBS Multi-AZ (via EFS or FSx)
- Azure Files with zone-redundant storage
- GCP Filestore with regional redundancy
Example: Minimal HA Setup
Resilient Databases
MongoDB Replica Set
- Deploy MongoDB as a 3-node replica set.
- Use StatefulSets and persistent volumes.
- Prefer managed services with automatic failover.
Elasticsearch Cluster
- Use 3 data nodes and 3 master nodes.
- Enable snapshot-based backups.
- Ensure cluster quorum during restarts or scaling.
Redis HA
- Use Redis Sentinel or Redis Cluster.
- Use persistent storage and multi-zone replication.
- Prefer managed Redis services like AWS ElastiCache or Azure Cache for Redis.
Storage Redundancy
- Ensure shared volumes (for uploads or workspace files) are RWX and support replication.
- Use cloud-native backup and snapshot solutions.
Monitoring and Self-Healing
- Use Prometheus and Grafana for live dashboards and alerting.
- Implement Kubernetes PodDisruptionBudgets (PDBs) to prevent all pods from being evicted at once.
- Add Horizontal Pod Autoscalers (HPA) for runtime services.