A D Vishnu Prasad

Director of Cloud Engineering @ Team8Solutions, Freelancer

Locust in Kubernetes for Performance Testing: A Powerful Combination

Performance testing ensures your applications gracefully handle the anticipated—and even the unanticipated—demands of real-world use. Locust, an open-source load testing framework, and Kubernetes, a container orchestration system, offer a potent mix for streamlining and scaling your performance testing efforts.

Why Locust?

Python Power: Locust uses Python to define user behavior, making test creation intuitive and flexible. If you can code it, Locust can simulate it.

Distributed Testing: Effortlessly simulate massive numbers of concurrent users by running Locust in a distributed mode.

Elegant Web UI: Monitor your tests in real-time, gain deep insights into performance metrics, and identify bottlenecks thanks to Locust’s user-friendly interface.

Why Kubernetes?

Scalability: Seamlessly provision and manage the resources your Locust deployment needs. Spin up workers as required and scale down when testing is complete.

Resilience: Kubernetes protects your test environment. If a worker node goes down, it automatically restarts pods, minimizing test disruption.

Portability: Replicate your Locust test infrastructure across different environments (testing, staging, production) with ease.

Locust UI

Step 1 : Create kubernetes manifests

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---
apiVersion: v1
kind: ConfigMap
metadata:
  name: locust-script-cm
data:
  locustfile.py: |
    from locust import HttpUser, between, task
    import time


    class Quickstart(HttpUser):
        wait_time = between(1, 5)

        @task
        def google(self):
            self.client.request_name = "google"
            self.client.get("https://google.com/")

        @task
        def microsoft(self):
            self.client.request_name = "microsoft"
            self.client.get("https://microsoft.com/")

        @task
        def facebook(self):
            self.client.request_name = "facebook"
            self.client.get("https://facebook.com/")
---
apiVersion: apps/v1
kind: Deployment
metadata:
  annotations:
    deployment.kubernetes.io/revision: "1"
  labels:
    role: locust-master
    app: locust-master
  name: locust-master
spec:
  replicas: 1
  selector:
    matchLabels:
      role: locust-master
      app: locust-master
  strategy:
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 1
    type: RollingUpdate
  template:
    metadata:
      labels:
        role: locust-master
        app: locust-master
    spec:
      containers:
      - image: locustio/locust
        imagePullPolicy: Always
        name: master
        args: ["--master"]
        volumeMounts:
          - mountPath: /home/locust
            name: locust-scripts
        ports:
        - containerPort: 5557
          name: bind
        - containerPort: 5558
          name: bind-1
        - containerPort: 8089
          name: web-ui
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      volumes:
      - name: locust-scripts
        configMap:
          name: locust-script-cm
---
apiVersion: apps/v1
kind: Deployment
metadata:
  annotations:
    deployment.kubernetes.io/revision: "1"
  labels:
    role: locust-worker
    app: locust-worker
  name: locust-worker
spec:
  replicas: 1 # Scale it as per your need
  selector:
    matchLabels:
      role: locust-worker
      app: locust-worker
  strategy:
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 1
    type: RollingUpdate
  template:
    metadata:
      labels:
        role: locust-worker
        app: locust-worker
    spec:
      containers:
      - image: locustio/locust
        imagePullPolicy: Always
        name: worker
        args: ["--worker", "--master-host=locust-master"]
        volumeMounts:
          - mountPath: /home/locust
            name: locust-scripts
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
        resources:
          requests:
            memory: "1Gi"
            cpu: "1"
          limits:
            memory: "1Gi"
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      volumes:
      - name: locust-scripts
        configMap:
          name: locust-script-cm
---
apiVersion: v1
kind: Service
metadata:
  labels:
    role: locust-master
  name: locust-master
spec:
  type: ClusterIP
  ports:
  - port: 5557
    name: master-bind-host
  - port: 5558
    name: master-bind-host-1
  selector:
    role: locust-master
    app: locust-master
---
apiVersion: v1
kind: Service
metadata:
  labels:
    role: locust-ui
  name: locust-ui
spec:
  type: LoadBalancer
  ports:
  - port: 8089
    targetPort: 8089
    name: web-ui
  selector:
    role: locust-master
    app: locust-master

Step 2 : Scale

If you want to scale more worker to support more requests per seconds, you can do that by just scaling up the worker pods

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kubectl scale --replicas=5 deploy/locust-worker -n locust
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locust-master-74c9f6db7c-klk4l   1/1     Running   0          18m
locust-worker-6674d66d5-kgxlp    1/1     Running   0          6s
locust-worker-6674d66d5-m8bdf    1/1     Running   0          6s
locust-worker-6674d66d5-r9v7p    1/1     Running   0          6s
locust-worker-6674d66d5-z2w4x    1/1     Running   0          6s
locust-worker-6674d66d5-zfswz    1/1     Running   0          19m

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