mirror of https://github.com/istio/istio.io.git
207 lines
6.8 KiB
Markdown
207 lines
6.8 KiB
Markdown
---
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title: Fault Injection
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description: This task shows you how to inject faults to test the resiliency of your application.
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weight: 20
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keywords: [traffic-management,fault-injection]
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aliases:
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- /docs/tasks/fault-injection.html
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---
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> This task uses the new [v1alpha3 traffic management API](/blog/2018/v1alpha3-routing/). The old API has been deprecated and will be removed in the next Istio release. If you need to use the old version, follow the docs [here](https://archive.istio.io/v0.7/docs/tasks/traffic-management/).
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This task shows you how to inject faults to test the resiliency of your application.
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## Before you begin
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* Set up 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 fault injection discussion in the
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[Traffic Management](/docs/concepts/traffic-management) concepts doc.
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* Apply application version routing by either performing the
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[request routing](/docs/tasks/traffic-management/request-routing/) task or by
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running the following commands:
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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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$ istioctl replace -f @samples/bookinfo/networking/virtual-service-reviews-test-v2.yaml@
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{{< /text >}}
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## Injecting an HTTP delay fault
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To test the Bookinfo application microservices for resiliency, inject a 7s delay
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between the `reviews:v2` and `ratings` microservices for user `jason`. This test
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will uncover a bug that was intentionally introduced into the Bookinfo app.
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Note that the `reviews:v2` service has a 10s hard-coded connection timeout for
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calls to the ratings service. Even with the 7s delay that you introduced, you
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still expect the end-to-end flow to continue without any errors.
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1. Create a fault injection rule to delay traffic coming from the test user
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`jason`.
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{{< text bash >}}
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$ istioctl replace -f @samples/bookinfo/networking/virtual-service-ratings-test-delay.yaml@
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{{< /text >}}
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1. Confirm the rule was created:
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{{< text bash yaml >}}
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$ istioctl get virtualservice ratings -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: 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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- fault:
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delay:
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fixedDelay: 7s
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percent: 100
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match:
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- headers:
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cookie:
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regex: ^(.*?;)?(user=jason)(;.*)?$
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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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- route:
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- destination:
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host: ratings
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subset: v1
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{{< /text >}}
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Allow several seconds for the new rule to propagate to all pods.
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## Testing the delay configuration
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1. Open the [Bookinfo](/docs/examples/bookinfo) web application in your browser.
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1. On the `/productpage`, log in as user `jason`.
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You expect the Bookinfo home page to load without errors in approximately
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7 seconds. However, there is a problem: the Reviews section displays an error
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message:
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{{< text plain >}}
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Error fetching product reviews!
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Sorry, product reviews are currently unavailable for this book.
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{{< /text >}}
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1. View the web page response times:
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1. Open the *Developer Tools* menu in IE, Chrome or Firefox (typically, key combination _Ctrl+Shift+I_ or _Alt+Cmd+I_).
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1. Open the Network tab
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1. Reload the `productpage` web page. You will see that the webpage actually
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loads in about 6 seconds.
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## Understanding what happened
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You've found a bug. There are hard-coded timeouts in the microservices that have
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caused the `reviews` service to fail.
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The timeout between the
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`productpage` and the `reviews` service is 6 seconds - coded as 3s + 1 retry
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for 6s total. The timeout between the `reviews` and `ratings`
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service is hard-coded at 10 seconds. Because of the delay we introduced, the `/productpage` times out prematurely and throws the error.
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Bugs like this can occur in typical enterprise applications where different teams
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develop different microservices independently. Istio's fault injection rules help you identify such anomalies without impacting end users.
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> Notice that the fault injection test is restricted to when the logged in user is
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`jason`. If you login as any other user, you will not experience any delays.
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## Fixing the bug
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You would normally fix the problem by:
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1. Either increasing the
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`/productpage` timeout or decreasing the `reviews` to `ratings` service timeout
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1. Stopping and restarting the fixed microservice
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1. Confirming that the `/productpage` returns its response without any errors.
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However, you already have this fix running in v3 of the reviews service, so you
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can simply fix the problem by migrating all traffic to `reviews:v3` as described
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in the [traffic shifting](/docs/tasks/traffic-management/traffic-shifting/) task.
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## Exercise
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Change the delay rule to use a 2.8 second delay and then run it against the v3
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version of reviews.
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## Injecting an HTTP abort fault
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Another way to test microservice resiliency is to introduce an HTTP abort fault.
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In this task, you will introduce an HTTP abort to the `ratings` microservices for
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the test user `jason`.
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In this case, you expect the page to load immediately and display the `product
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ratings not available` message.
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1. Create a fault injection rule to send an HTTP abort for user `jason`:
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{{< text bash >}}
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$ istioctl replace -f @samples/bookinfo/networking/virtual-service-ratings-test-abort.yaml@
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{{< /text >}}
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1. Confirm the rule was created:
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{{< text bash yaml >}}
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$ istioctl get virtualservice ratings -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: 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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- fault:
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abort:
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httpStatus: 500
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percent: 100
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match:
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- headers:
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cookie:
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regex: ^(.*?;)?(user=jason)(;.*)?$
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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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- route:
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- destination:
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host: ratings
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subset: v1
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{{< /text >}}
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## Testing the abort configuration
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1. Open the [Bookinfo](/docs/examples/bookinfo) web application in your browser.
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1. On the `/productpage`, log in as user `jason`.
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If the rule propagated successfully to all pods, the page loads
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immediately and the `product ratings not available` message appears.
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1. Log out from user `jason` and the rating stars show up successfully on the
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application's `/productpage`.
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## Cleanup
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1. Remove the application routing rules:
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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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