13 Apr 2019

Load Testing of a Microservice. Kubernetes way.

Let's assume there is a microservice represented by a composition of containers running on a K8s cluster somewhere in a cloud, e.g. Oracle Kubernetes Engine (OKE). At some point we want to quickly stress test a specific microservice component or the entire microservice. So we want to know how it works under the load, how it handles many subsequent requests coming from many parallel clients. The good news is that we have already a tool for that. Up and running. This is the Kubernetes cluster itself.

We're going to use Kubernetes Job for this testing described in the following manifest file:
apiVersion: batch/v1
kind: Job
metadata:
   name: job-load
spec:
   parallelism: 50   
   template:
     spec:
       containers:
         - name: loader
           image: eugeneflexagon/aplpine-with-curl:1.0.0
           command: ["time", "curl", "http://my_service:8080/my_path?[1-100]"]     
       restartPolicy: OnFailure   
This job is going to spin up 50 pods running in parallel and sending 100 requests each to my_service on port 8080 and with path my_path. Having the job created and started by invoking
kubectl  apply -f loadjob.yaml
We can observe all 50 pods created by the job using

kubectl get pods -l job-name=job-load
NAME             READY     STATUS      RESTARTS   AGE
job-load-4n262   1/2       Completed   1          12m
job-load-dsqtc   1/2       Completed   1          12m
job-load-khdn4   1/2       Completed   1          12m
job-load-kptww   1/2       Completed   1          12m
job-load-wf9pd   1/2       Completed   1          12m
...

If we look at the logs of any of these pods

kubectl logs job-load-4n262

We'll see something like the following:
[1/100]: http://my_service.my_namespace:8080/my_path?1 --> <stdout>
{"id":456,"content":"Hello world!"}

[2/100]: http://my_service.my_namespace:8080/my_path?2 --> <stdout>
{"id":457,"content":"Hello world!"}

[3/100]: http://my_service.my_namespace:8080/my_path?3 --> <stdout>
{"id":458,"content":"Hello world!"}

....

real    0m 10.04s
user    0m 0.00s
sys     0m 0.04s

That's it!

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