Inject Faults to your APIs
Fault injection is a testing technique for detecting how your platform will behave when some components don't run in the usual way.
API7 Cloud allows users to configure the Fault Injection plugin to inject some errors for their services or routes so that they can simulate the API Gateway faults.
The Fault Injection plugin has two run modes: Abort Request and Delay Request. When it works in
Abort Request, Apache APISIX will reject API requests immediately, and Apache APISIX
will set the given status code and response body; when the run mode is Delay Request, Apache APISIX
will delay the request for the given period and forward the request normally.
Create Service and Route
We'll create a service with the following details in this guide.
- The service name is
fault-injection-app. - The path prefix is
/v1. - The HTTP Host is
fault-injection.httpbin.org. - The upstream URL is
https://httpbin.org.
Besides, we'll create a route inside the fault-injection-app Service.
- The route name is
json. - The path is
/json(exact match). - Accepted HTTP method is
GET.
If you don't know how to configure a service and route, please refer to the Getting Started guides first.
Test the Abort Request Mode
Now let's add the Fault Injection plugin to the fault-injection-app Service.
You can enter the fault-injection-app details page, click on the Add Plugin button,
select Fault Injection plugin, and fill out the form.
You can also configure the Fault Injection plugin on the route level, in such a case, only the route will be affected by this plugin.
Then let's send a request and see what will happen.
curl http://127.0.0.1:9080/v1/json -H 'Host: fault-injection.httpbin.org' -i
HTTP/1.1 503 Service Temporarily Unavailable
Date: Mon, 13 Jun 2022 01:24:03 GMT
Content-Type: text/plain; charset=utf-8
Transfer-Encoding: chunked
Connection: keep-alive
Server: APISIX/2.15.0
Injected 503 error
As you can see, Apache APISIX rejects the request.
The status code (503) and body (Injected 503 error) are expected.
We set the percentage to 100% so every request you sent will be rejected by
Apache APISIX. In the real world, you may want to reject the portion of requests so that
the percentage might be 10%, 30% 50%, and so on. But please note that Apache APISIX
uses a random algorithm to decide if the request should be rejected (according to the
specific percentage), so it doesn't mean there will have exactly 30 requests rejected
if you sent 100 requests and the portion is 30%. From a statistical point of view, the larger
the sample, the more accurate the results.
Test the Delay Request Mode
Let's update the Fault Injection plugin on the fault-injection-app Service.
We change the run mode from Abort Request to Delay Request, and the delay duration is
1000ms.
To feel the delay, let's send 5 requests with/without the Fault Injection plugin
perspective, and compare the difference in the average request time.
for ((i=0; i < 5; i++)); do
curl http://127.0.0.1:9080/v1/json -H 'Host: fault-injection.httpbin.org' -s -o/dev/null -w '%{time_total}\n'
done
1.900560
2.206164
1.933959
1.907882
1.991174
And let's disable the Fault Injection plugin and send 5 requests again.
0.938746
1.010053
0.964290
1.192605
0.946725
As you can see, the request times are about 1 second less, but it's not accurate due
to the Internet.
Again, we set the percentage to 100%, so every request you sent will be delayed by
Apache APISIX. In the real world, you may want to delay the portion of requests so that
the percentage might be 10%, 30% 50%, and so on. But please note that Apache APISIX
uses a random algorithm to decide if the request should be delayed (according to the
specific percentage). So it doesn't mean there will have exactly 30 requests will be delayed
if you sent 100 requests and the portion is 30%. From a statistical point of view, the larger
the sample, the more accurate the results.