https://blog.kelebeklabs.com/2022/12/load-testing-with-ruby-jmeter.html

load_testing_for_uploading.rb

# wget https://dlcdn.apache.org//jmeter/binaries/apache-jmeter-5.5.zip
# unzip apache-jmeter-5.5.zip
# ruby load_testing_for_uploading.rb

# results(takes some time to generate html output): apache-jmeter-5.5/bin/jmeter -g ./results.jtl -o ./results
# npx http-server results

require 'ruby-jmeter'
require 'uri'

module URI
    def self.encode(url)
        url
    end

    def self.decode(url)
        url
    end    
end

# all options our test plan can use, like filenames__1 is foo1.pdf, filenames_11 is foo1.xls
def user_variables
  arr = []
  index = 1
  (%w(.pdf .xls .docx .zip .jpg .) + ['']).each do |ext|
    (1..10).each do |k|
      arr << {name: "filenames__#{index}", value: "foo#{k}#{ext}"}
      arr << {name: "mimetypes__#{index}", value: "application/#{ext}"}

      index = index + 1
    end
  end

  arr
end

FileUtils.rm('jmeter.log') if File.exist?('jmeter.log')
FileUtils.rm('results.jtl') if File.exist?('results.jtl')

test do
    threads count: 100, duration: 120 do # if 100 customers are keep uploading new files in 2 minutes
      think_time 2000, 5000 # at least 2 seconds between uploads of a customer, up to 5 seconds
      variables user_variables # hash with all options our test plan can use

      transaction name: 'Getting the folder code' do
        post name: 'Get session', url: 'https://api.foldercode.com/api/v1/uploading_sessions' do
          duration_assertion duration: 1000 # even 1 second is too much, the response should be less than that

          json_path_postprocessor referenceNames: 'id', jsonPathExprs: '.id', match_numbers: 1
          json_path_postprocessor referenceNames: 'folder_code', jsonPathExprs: '.folderCode', match_numbers: 1
        end
      end

      exists 'id' do
          # this code to record the session ids we're using, can be helpful to delete only the files we uploaded
          bsh_post script: <<-EOS.strip_heredoc
            artname = vars.get("folder_code");
            f = new FileOutputStream("obtained_folder_codes.csv", true);
            p = new PrintStream(f);
            this.interpreter.setOut(p);
            print(artname);
            f.close();
          EOS

        loops count: "${__Random(1,10)}" do # upload from 1 to 10 files per folder
          submit url: "https://api.foldercode.com/upload", fill_in: {"browserSession": "${id}"}, files: [{path: '/tmp/${__V(filenames__${__Random(1,70)})}', paramname: 'file', mimetype: '${__V(mimetypes__${__Random(1,70)})}'}], 'DO_MULTIPART_POST' => true
        end
      end
    end
  end.run(
    path: './apache-jmeter-5.5/bin/',
    file: 'jmeter.jmx',
    log: 'jmeter.log',
    jtl: 'results.jtl'
    )

# ruby code to generate random files in different sizes and extensions
# require 'securerandom'; (%w(.pdf .xls .docx .zip .jpg .) + ['']).each { |ext| 10.times { |i| File.open("/tmp/foo#{i+1}#{ext}", 'wb') { |f| (i<=5 ? rand(0.2..5.3) : rand(5.4..99.3)).to_i.times { f.write( SecureRandom.random_bytes( 1024 * 1024 ) ) } } } }
# 
# to see which files are uploaded by this script
# require 'csv'; CSV.read('obtained_folder_codes.csv').flatten.uniq