GraphQL load testing

.gitignore

summaries

README.md

GraphQL load testing using k6

This repo contains the scripts that were used to run a load test against GOV.UK pages that were converted to use GraphQL.

Files

• data.json: contains a list of pages to test with their URL and a list of VU (virtual user) numbers to test with.
• k6.js: the k6 script that runs the actual load test.
• runner.rb: a wrapper around k6.js which sequentially runs the load test against each example defined in data.json.

Running a load test

1. Install k6.

   brew install k6

2. Run the runner script.

   ruby runner.rb

3. The output will be in ./summaries/data_amalgam.csv.

data.json

{
  "pages": [
    { "name": "government_response", "basePath": "/government/news/new-child-car-seat-rules-no-change-for-existing-booster-seats" },
    { "name": "ministers_index", "basePath": "/government/ministers" },
    { "name": "news_story", "basePath": "/government/news/government-financial-boost-for-small-and-medium-housebuilders" },
    { "name": "press_release", "basePath": "/government/news/a-very-merry-fishmas-for-south-east-anglers" },
    { "name": "role_1", "basePath": "/government/ministers/prime-minister" },
    { "name": "role_2", "basePath": "/government/ministers/secretary-of-state-for-culture-media-and-sport--3" },
    { "name": "role_3", "basePath": "/government/ministers/captain-of-the-kings-bodyguard-of-the-yeoman-of-the-guard-lords-deputy-chief-whip" },
    { "name": "world_index", "basePath": "/world" },
    { "name": "world_news_story", "basePath": "/government/news/british-high-commission-marks-his-majesty-king-charles-iiis-birthday-with-brilliantly-british-celebrations"}
  ],
  "vus": [10, 25, 50, 100, 200, 400, 800],
  "sleepPeriod": 30,
  "websiteRoot": "https://www-origin.staging.publishing.service.gov.uk"
}

k6.js

import http from "k6/http";
import { sleep } from "k6";

const data = JSON.parse(open("./data.json"));
const scenarios = {};
const baseScenarioOptions = {
  executor: "per-vu-iterations",
  maxDuration: "60s",
  iterations: 1,
  exec: "govuk_test",
};

for (const page of data.pages) {
  for (const vus of data.vus) {
    scenarios[`${page.name}_${vus}`] = {
      ...baseScenarioOptions,
      vus,
      env: {
        GRAPHQL: "false",
        BASE_PATH: page.basePath,
        WEBSITE_ROOT: data.websiteRoot,
      },
    };

    scenarios[`${page.name}_${vus}_graphql`] = {
      ...baseScenarioOptions,
      vus,
      env: {
        GRAPHQL: "true",
        BASE_PATH: page.basePath,
        WEBSITE_ROOT: data.websiteRoot,
      },
    };
  }
}

const { SCENARIO } = __ENV;
const options = {
  scenarios: SCENARIO ? { [SCENARIO]: scenarios[SCENARIO] } : scenarios,
};

function govuk_test() {
  let url = `${__ENV.WEBSITE_ROOT}${__ENV.BASE_PATH}`;

  if (__ENV.GRAPHQL === "true") url += `?graphql=${__ENV.GRAPHQL}`

  const res = http.get(url);

  sleep(1);
}

export { govuk_test, options };

runner.rb

#!/usr/bin/env ruby
# frozen_string_literal: true

require 'csv'
require 'json'
require 'fileutils'

data = JSON.parse(File.read('data.json'))
page_names = data['pages'].map { |x| x['name'] }
vuss = data['vus']
scenarios = []

page_names.each do |page_name|
  vuss.each do |vus|
    scenarios << "#{page_name}_#{vus}"
    scenarios << "#{page_name}_#{vus}_graphql"
  end
end

FileUtils.mkdir_p('summaries')

scenarios.each_with_index do |scenario, index|
  puts "\n#{Time.now} Starting scenario: #{scenario}"
  `SCENARIO=#{scenario} k6 run k6.js --summary-export summaries/#{scenario}_summary.json`
  puts "#{Time.now} Finished scenario: #{scenario}"
  sleep(data['sleepPeriod']) unless index == scenarios.size - 1
end

OUTPUT_LOOKUP = {
  'request_count' => %w[metrics http_reqs count],
  'request_duration_avg' => %w[metrics http_req_duration avg],
  'request_duration_p90' => ['metrics', 'http_req_duration', 'p(90)'],
  'request_duration_p95' => ['metrics', 'http_req_duration', 'p(95)'],
  'failed_request_count' => %w[metrics http_req_failed passes] # this is correct because k6 loves the weird double negative of a failure pass
}.freeze

CSV.open('summaries/data_amalgam.csv', 'w') do |csv|
  csv << ['page_name', 'vus', 'graphql?'] + OUTPUT_LOOKUP.keys
  page_names.each do |page_name|
    vuss.each do |vus|
      [false, true].each do |graphql|
        filename = if graphql
                     "summaries/#{page_name}_#{vus}_graphql_summary.json"
                   else
                     "summaries/#{page_name}_#{vus}_summary.json"
                   end

        summary_data = JSON.parse(File.read(filename))

        csv << [page_name, vus, graphql] +
          OUTPUT_LOOKUP.map { |_, dig_path| summary_data.dig(*dig_path) }
      end
    end
  end
end