Kubernetes service
Kubernetes service manage a pod’s networking. It specifies whether your pods are exposed internally (ClusterIP), externally (NodePort or LoadBalancer) or as a CNAME of other DNS entries (externalName).
As an example this foo-service will expose the pods with label app: foo. Any requests sent to the node on port 30007 will be forwarded to the pod on port 80.
apiVersion: v1
kind: Service
metadata:
name: foo-service
spec:
type: NodePort
selector:
app: foo
ports:
- port: 80
targetPort: 80
nodePort: 30007
Istio virtualservice
Istio virtualservice is one level higher than Kuberenetes service. It can be used to apply traffic routing, fault injection, retries and many other configurations to services.
As an example this foo-retry-virtualservice will retry 3 times with a timeout 2s each for failed requests to foo.
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: foo-retry-virtualservice
spec:
hosts:
- foo
http:
- route:
- destination:
host: foo
retries:
attempts: 3
perTryTimeout: 2s
Another example of this foo-delay-virtualservice will apply a 0.5s delay to 0.1% of requests to foo.
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: foo-delay-virtualservice
spec:
hosts:
- foo
http:
- fault:
delay:
percentage:
value: 0.1
fixedDelay: 5s
route:
- destination:
host: foo
Ref
https://kubernetes.io/docs/concepts/services-networking/service/
https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/
https://istio.io/latest/docs/reference/config/networking/virtual-service/
https://istio.io/latest/docs/concepts/traffic-management/#virtual-services