Request Code Injection with Istio Route Rules

Istio route rules can be used to redirect arbitrary service requests to an intermediary that performs custom logic (e.g., validation or transformation) on a request and/or response body, before forwarding the request/response. This can be accomplished without modifying any of the application services themselves.

To demonstrate, this sample injects a simple verifier in front of calls to the details service of the Bookinfo sample. The verifier is a simple python service that verifies (actually, just pretends to verify) one of the fields of the details response, before returning it to the caller.

Before you begin

1. Install Istio by following the istio install instructions.

2. Start the Bookinfo sample.

3. Set the default version routing for the bookinfo sample.

   istioctl create -f samples/bookinfo/kube/route-rule-all-v1.yaml

At this point you should be able to point your browser to the BookInfo URL (http://$GATEWAY_URL/productpage) to see the v1 version of the application.

Running the verifier

1. Run the verifier.

   kubectl create -f <(istioctl kube-inject -f deploy.yaml)

2. Set the route rules to inject the verifier into the request path.

   istioctl create -f route-details-verified.yaml

3. Refresh the Bookinfo URL in your browser.

You should now see the string (verified) appended to the end of the Publisher property in the Book Details section, indicating that the verifier was invoked during the GET request on the details service.

Cleanup

kubectl delete -f deploy.yaml
kubectl delete routerules --all