In modern cloud-native environments like SAP Kyma, microservices communicate frequently over the network. Ensuring that these communications are reliable, efficient, and resilient is crucial for building scalable applications. Two key patterns that help achieve this are load balancing and circuit breakers.
SAP Kyma leverages Istio, a powerful service mesh, to provide built-in support for these patterns. This article explains how to implement load balancing and circuit breaker mechanisms in Kyma to improve service reliability and performance.
Load balancing distributes incoming network traffic across multiple instances of a service, ensuring no single instance is overwhelmed. It improves resource utilization, reduces latency, and increases fault tolerance.
Common load balancing strategies include:
Circuit breakers detect failures and prevent continuous requests to unhealthy services. When a failure threshold is reached, the circuit “opens,” stopping requests temporarily to allow the service to recover. This prevents cascading failures and improves system resilience.
Istio’s service mesh runs alongside Kyma and manages microservice traffic at the network layer through sidecar proxies. It provides advanced traffic management features, including:
You configure load balancing by defining DestinationRules in Istio, which specify policies for service subsets.
apiVersion: networking.istio.io/v1beta1
kind: DestinationRule
metadata:
name: my-service
namespace: default
spec:
host: my-service.default.svc.cluster.local
trafficPolicy:
loadBalancer:
simple: ROUND_ROBIN
Apply this configuration with:
kubectl apply -f destinationrule.yaml
This directs Istio to distribute requests evenly among all healthy instances of my-service.
Circuit breakers are also configured in the DestinationRule resource by specifying connection and request thresholds.
apiVersion: networking.istio.io/v1beta1
kind: DestinationRule
metadata:
name: my-service-cb
namespace: default
spec:
host: my-service.default.svc.cluster.local
trafficPolicy:
connectionPool:
tcp:
maxConnections: 10
http:
http1MaxPendingRequests: 5
maxRequestsPerConnection: 2
outlierDetection:
consecutiveErrors: 5
interval: 10s
baseEjectionTime: 30s
maxEjectionPercent: 50
Apply the configuration:
kubectl apply -f destinationrule-cb.yaml
You can combine both configurations in a single DestinationRule for robust traffic management:
apiVersion: networking.istio.io/v1beta1
kind: DestinationRule
metadata:
name: my-service-full
namespace: default
spec:
host: my-service.default.svc.cluster.local
trafficPolicy:
loadBalancer:
simple: LEAST_CONN
connectionPool:
tcp:
maxConnections: 20
http:
http1MaxPendingRequests: 10
maxRequestsPerConnection: 5
outlierDetection:
consecutiveErrors: 3
interval: 5s
baseEjectionTime: 60s
maxEjectionPercent: 25
This example uses least connections for load balancing with a circuit breaker that quickly ejects failing endpoints.
Implementing load balancing and circuit breakers in SAP Kyma using Istio’s powerful traffic management features is essential for building resilient and performant microservices. These patterns help distribute workload efficiently and protect services from cascading failures.
By adopting these configurations, SAP Kyma developers can ensure smoother, more reliable interactions across microservices and deliver better experiences in SAP cloud-native applications.