Build load test tool Locust 1.1 on Docker

Introduction

When developing a Web system, I think it is necessary to know in advance not only whether it behaves as expected, but also how much load it can withstand.

This time, I would like to build Locust, a load test tool, on Docker and try it first.

Features of Locust

• Since the scenario is written in Python script, flexible scenario can be created.
• Source code control is possible because the test scenario is a script
• Since the required server resources are small, it is easy to load with a small number of attack servers.
• Simple result display

environment

• The Docker version is 19.03.12.
• Locust version is 1.1.

The client PC will be Windows 10 Pro.

Official documents, etc.

The official documents are as follows.

Locust Official Document Locust github

Construction procedure

1. 1. Install Docker Desktop Install Docker DeskTop from the following. https://www.docker.com/products/docker-desktop

2. Get the docker-compose.yml file Create a folder in any location and download the docker-compose.yml file from the following. https://github.com/locustio/locust/tree/master/examples/docker-compose

Change the -H part of the master command to the page you want to test.

version: "3"
services:
  web:
    build:
      context: ./apache-php
    ports: 
      - 80:80
    privileged: true
    links:
      - db
    volumes:
      - "./lara-d/:/var/www/html"
      - "./apache-php/apache.conf:/etc/httpd/conf/httpd.conf"
    container_name: "apache-php"
version: '3'

services:
  master:
    image: locustio/locust
    ports:
     - "8089:8089"
    volumes:
      - ./:/mnt/locust
    command: -f /mnt/locust/locustfile.py --master -H http://master:8089
  
  worker:
    image: locustio/locust
    volumes:
      - ./:/mnt/locust
    command: -f /mnt/locust/locustfile.py --worker --master-host master

3. 3. Creating locustfile.py locustfile.py is a file that describes the scenario and should be placed in the same location as docker-compose.yml.

This time, we will create a script to make a simple HTTP request.

from locust import HttpUser, task, between

class MyUser(HttpUser):
    wait_time = between(5, 10)  #Specify the timing to launch user

    @task(1)
    def index(self):
        
        url = '/api/test.php' #Specify the place to apply the load
        params = {'id':'0001'} #Specify parameters as needed

        headers = {'x-api-key':'***********'} #Add header items as needed

        self.client.get(url=url,params=params,headers=headers) #Send GET request

Execution method

1. 1. Start Docker

Open a command prompt, change to the folder where you placed docker-compose.yml, and execute the following command.

docker-compose up -d

If you want to increase the number of workers and load them in parallel, specify them at startup. I think it's okay to write it in an yml file.

docker-compose up -d --scale worker=3

2. parameter settings After starting Docker, display Locust in your browser. http://localhost:8089/

Enter the number of users and the speed at which the users will start up, and press Start to execute. (The host will be the one set in yml)