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06-istio-route-rules.md

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Istio Route Rules

The Istio Ingress Controller provides an advanced feature set based Envoy's unique traffic management capabilities. This section will demonstrates how to dynamically configure the Istio Ingress Controller using the Istio Pilot and the istioclt command line tool.

The istio-test HTTP service will be used to demonstrate Istio's traffic management features.

Test the Istio Ingress Controller

Deploy v1 of the istio-test application:

kubectl apply -f deployments/istio-test-v1.yaml

Expose the istio-test-v1 deployment:

kubectl apply -f services/istio-test.yaml

Create the istio-test ingress object:

kubectl apply -f ingress/istio-test.yaml

Interact with the Istio Ingress Controller

In this section the curl command line tool will be used to test the basic functionality of the Istio Ingress Controller.

Retrieve the istio-ingress external IP address:

ISTIO_INGRESS_IP=$(kubectl get svc istio-ingress \
  -o jsonpath='{.status.loadBalancer.ingress[0].ip}')

curl -i http://${ISTIO_INGRESS_IP}

HTTP/1.1 200 OK
date: Fri, 18 Aug 2017 16:26:40 GMT
content-length: 14
content-type: text/plain; charset=utf-8
x-envoy-upstream-service-time: 1
server: envoy

istio-test-v1

Testing Istio Route rules

The Isito Ingress Controller can be dynamically configured by the Istio Pilot to provide more advanced routing between external clients and services running in a Kubernetes cluster. To demonstrate these features we need to deploy v2 of the istio-test HTTP service:

kubectl apply -f deployments/istio-test-v2.yaml

At this point v1 and v2 of the istio-test service should be running:

kubectl get pods -l app=istio-test

NAME                             READY     STATUS    RESTARTS   AGE
istio-test-v1-XXXXXXXXX-XXXXX    1/1       Running   0          5m
istio-test-v2-XXXXXXXXX-XXXXX    1/1       Running   0          4m

Run the curl command a few times and observe the response from the Istio Ingress Controller:

curl http://${ISTIO_INGRESS_IP}

istio-test-v1

curl http://${ISTIO_INGRESS_IP}

istio-test-v2

Notice both v1 and v2 of the istio-test service are responding.

Add a Route Rule

An Istio Route Rule can be used to force all clients to hit v2 of the istio-test service.

Create a route rule and save it to a file named istio-test-default.yaml:

cat > istio-test-default.yaml <<EOF
type: route-rule
name: istio-test-default
namespace: default
spec:
  destination: istio-test.default.svc.cluster.local
  route:
    - tags:
        version: v2
      weight: 100
EOF

Submit the route rule using the istioctl command:

istioctl create -f istio-test-default.yaml

Route rules are stored in Kubernetes ThirdPartyResources

kubectl get thirdpartyresources

NAME                    DESCRIPTION           VERSION(S)
istio-config.istio.io   Istio configuration   v1alpha1

Inspect the details of the istio-test-default route rule configuration:

kubectl get istioconfigs

NAME                            KIND
route-rule-istio-test-default   IstioConfig.v1alpha1.istio.io

Use the kubectl describe command to get more details:

kubectl describe istioconfigs route-rule-istio-test-default

Name:         route-rule-istio-test-default
Namespace:    default
Labels:       <none>
Annotations:  <none>
API Version:  istio.io/v1alpha1
Kind:         IstioConfig
Metadata:
  Creation Timestamp:   2017-08-18T16:29:34Z
  Resource Version:     10775
  Self Link:            /apis/istio.io/v1alpha1/namespaces/default/istioconfigs/route-rule-istio-test-default
  UID:                  6b7530f4-8432-11e7-a05d-42010a80004f
Spec:
  Destination:  istio-test.default.svc.cluster.local
  Route:
    Tags:
      Version:  v2
    Weight:     100
Events:         <none>

The istioctl command can also be used:

istioctl get route-rules istio-test-default

destination: istio-test.default.svc.cluster.local
route:
- tags:
    version: v2
  weight: 100

Interact with the Istio Ingress Controller

With the istio-test-default route rule in place re-run the curl command a few times and observe the response:

curl http://${ISTIO_INGRESS_IP}

istio-test-v2

curl http://${ISTIO_INGRESS_IP}

istio-test-v2

Notice all traffic is handeled by v2 of the istio-test service.