K
Q

What is the difference between Istio VirtualService and Kubernetes Service?

December 12, 2018

As I understand, Istio 

VirtualService
is kind of abstract thing, which tries to add an interface to the actual implementation like the service in Kubernetes or something similar in Consul.

When use Kubernetes as the underlying platform for Istio, is there any difference between Istio 

VirtualService
and Kubernetes 
Service
or are they the same?

-- koly
kubernetes
istio

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3 Answers

January 19, 2021
<h3>Kubernetes service</h3>

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
<h3>Istio virtualservice</h3>

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-service
    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-service
<h3>Ref</h3>

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

-- Victor Wong
Source: StackOverflow
December 12, 2018

Istio's VirtualServices provides, as every Istio's extensions, some additionals features such as external traffic routing/management (Pod to external communication, HTTPS external communication, routing, url rewriting...).

Take a look at this doc about it for more details : https://istio.io/docs/reference/config/networking/virtual-service

They can be both useful, as you need "classic" Services to manage ingress traffic or service-to-service communication.

-- Steve
Source: StackOverflow
January 25, 2020

Virtual Service:

It defines a set of traffic routing rules to apply to a kubernetes service or subset of service based on the matching criteria. This is something similar to kubernetes Ingress object. It plays a key role on Istio's traffic management flexible and powerful.

Kubernetes Service:

It can be a logical set of pods and defined as an abstraction on top of pods which provides single DNS name or IP.

-- Subramanian Manickam
Source: StackOverflow