mirror of https://github.com/istio/istio.io.git
222 lines
7.3 KiB
Markdown
222 lines
7.3 KiB
Markdown
---
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title: Configuring Request Routing
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description: This task shows you how to configure dynamic request routing to multiple versions of a microservice.
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weight: 10
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aliases:
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- /docs/tasks/request-routing.html
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keywords: [traffic-management,routing]
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---
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This task shows you how to route requests dynamically to multiple versions of a
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microservice.
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## Before you begin
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* Setup Istio by following the instructions in the
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[Installation guide](/docs/setup/).
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* Deploy the [Bookinfo](/docs/examples/bookinfo/) sample application.
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* Review the [Traffic Management](/docs/concepts/traffic-management) concepts doc. Before attempting this task, you should be familiar with important terms such as *destination rule*, *virtual service*, and *subset*.
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## About this task
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The Istio [Bookinfo](/docs/examples/bookinfo/) sample consists of four separate microservices, each with multiple versions. The initial goal of this task is to
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apply a rule that routes all traffic to `v1` (version 1) of the ratings service. Later, you
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will apply a rule to route traffic based on the value of an HTTP request header.
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To illustrate the problem this task solves, access the Bookinfo app's `/productpage` in a browser and refresh several times. You’ll notice that sometimes the book review output contains star ratings and other times it does not. This is because without an explicit default service version to route to, Istio routes requests to all available versions
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in a round robin fashion.
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## Apply a virtual service
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To route to one version only, you apply virtual services that set the default version for the microservices.
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In this case, the virtual services will route all traffic to `v1` of each microservice.
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> Before continuing, be sure you don't have any existing virtual services applied
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to the Bookinfo app. If you already created conflicting virtual services for Bookinfo, you must use `replace` rather than `create` in the following command.
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1. Run the following command to apply the virtual services:
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{{< text bash >}}
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$ istioctl create -f @samples/bookinfo/networking/virtual-service-all-v1.yaml@
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{{< /text >}}
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Because configuration propagation is eventually consistent, wait a few seconds
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for the virtual services to take effect.
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1. Display the defined routes with the following command:
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{{< text bash yaml >}}
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$ istioctl get virtualservices -o yaml
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apiVersion: networking.istio.io/v1alpha3
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kind: VirtualService
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metadata:
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name: details
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...
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spec:
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hosts:
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- details
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http:
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- route:
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- destination:
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host: details
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subset: v1
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---
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apiVersion: networking.istio.io/v1alpha3
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kind: VirtualService
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metadata:
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name: productpage
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...
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spec:
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gateways:
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- bookinfo-gateway
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- mesh
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hosts:
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- productpage
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http:
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- route:
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- destination:
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host: productpage
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subset: v1
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---
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apiVersion: networking.istio.io/v1alpha3
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kind: VirtualService
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metadata:
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name: ratings
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...
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spec:
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hosts:
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- ratings
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http:
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- route:
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- destination:
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host: ratings
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subset: v1
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---
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apiVersion: networking.istio.io/v1alpha3
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kind: VirtualService
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metadata:
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name: reviews
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...
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spec:
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hosts:
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- reviews
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http:
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- route:
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- destination:
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host: reviews
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subset: v1
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---
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{{< /text >}}
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1. Display the corresponding `subset` definitions:
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{{< text bash >}}
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$ istioctl get destinationrules -o yaml
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{{< /text >}}
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You have configured Istio to route to the `v1` version of the Bookinfo microservices,
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including the `ratings` service.
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## Test the new routing configuration
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You can easily test the new configuration by once again refreshing the `/productpage`
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of the Bookinfo app.
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1. Open the Bookinfo site in your browser. The URL is `http://$GATEWAY_URL/productpage`, where `$GATEWAY_URL` is the External IP address of the ingress, as explained in
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the [Bookinfo](/docs/examples/bookinfo/#determining-the-ingress-ip-and-port) doc.
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Notice that the reviews part of the page displays with no rating stars, no
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matter how many times you refresh. This is because you configured Istio to route
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all traffic for the reviews service to the version `reviews:v1` and this
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version of the service does not access the star ratings service.
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You have successfully accomplished the first part of this task: route traffic to one
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version of a service.
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## Route based on user identity
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Next, you will change the route config so that all traffic from a specific user
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is routed to a specific service version. In this case, all traffic from a user
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named Jason will be routed to the service `reviews:v2`.
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Note that Istio doesn't have any special, built-in understanding of user
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identity. This example is enabled by the fact that the productpage service
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adds a custom "end-user" header to all outbound HTTP requests to the reviews
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service.
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Remember, `reviews:v2` is the version that includes the star ratings feature.
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1. Run the following command to enable the user-based routing:
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{{< text bash >}}
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$ istioctl replace -f @samples/bookinfo/networking/virtual-service-reviews-test-v2.yaml@
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{{< /text >}}
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1. Confirm the rule is created:
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{{< text bash yaml >}}
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$ istioctl get virtualservice reviews -o yaml
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apiVersion: networking.istio.io/v1alpha3
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kind: VirtualService
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metadata:
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name: reviews
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...
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spec:
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hosts:
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- reviews
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http:
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- match:
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- headers:
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end-user:
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exact: jason
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route:
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- destination:
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host: reviews
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subset: v2
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- route:
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- destination:
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host: reviews
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subset: v1
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{{< /text >}}
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1. On the `/productpage` of the Bookinfo app, log in as user `jason`.
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Refresh the browser. What do you see? The star ratings appear next to each
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review.
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1. Log in as another user (pick any name you wish).
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Refresh the browser. Now the stars are gone. This is because traffic is routed
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to `reviews:v1` for all users except Jason.
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You have successfully configured Istio to route traffic based on user identity.
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## Understanding what happened
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In this task, you used Istio to send 100% of the traffic to the `v1` version
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of each of the Bookinfo services. You then set a rule to selectively send traffic
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to version `v2` of the reviews service based on a custom "end-user" header added
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to the request by the productpage service.
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Note that Kubernetes services, like the Bookinfo ones used in this task, must
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adhere to certain restrictions to take advantage of Istio's L7 routing features.
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Refer to the [sidecar injection documentation](/docs/setup/kubernetes/sidecar-injection/#pod-spec-requirements) for details.
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In the [traffic shifting](/docs/tasks/traffic-management/traffic-shifting) task, you
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will follow the same basic pattern you learned here to configure route rules to
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gradually send traffic from one version of a service to another.
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## Cleanup
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1. Remove the application virtual services.
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{{< text bash >}}
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$ istioctl delete -f @samples/bookinfo/networking/virtual-service-all-v1.yaml@
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{{< /text >}}
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1. If you are not planning to explore any follow-on tasks, refer to the
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[Bookinfo cleanup](/docs/examples/bookinfo/#cleanup) instructions
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to shutdown the application.
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