Split the autoscale simulation script out to a separate file

Author: nbudin

.gitignore

@@ -103,3 +103,7 @@ cookbooks
 
 # Vite
 /vite.config.mts.timestamp-*.mjs
+
+# Autoscaling simulation output
+/scaling-graph.csv
+/scaling-graph.png

app/services/autoscale_servers_service.rb

@@ -1,16 +1,5 @@
-# Script to generate graph:
-# require "csv"
-# Time.zone = "America/New_York"
-# time = Time.local(2022, 10, 31)
-# data = []
-# while time < Time.local(2022, 11, 4)
-#   data << [time, AutoscaleServersService.scaling_target_for(time)]
-#   time += 15.minutes
-# end
-# CSV.open("scaling-graph.csv", "w") do |csv|
-#   csv << %w[Time Servers]
-#   data.each { |row| csv << row }
-# end
+# To simulate the effect of autoscaling as a CSV file:
+# bin/rails runner script/generate_simulated_autoscaling_graph.rb
 
 class AutoscaleServersService < CivilService::Service
   USERS_PER_INSTANCE = ENV.fetch("AUTOSCALE_USERS_PER_INSTANCE", "40").to_i

script/generate_simulated_autoscaling_graph.gnuplot

@@ -0,0 +1,13 @@
+set terminal png size 1200,600
+set output 'scaling-graph.png'
+set datafile separator ','
+set xdata time
+set timefmt '%Y-%m-%d %H:%M:%S'
+set format x '%I:%M%p'
+set xlabel 'Time'
+set ylabel 'Servers'
+set title 'Autoscaling Servers'
+set autoscale yfix
+set yrange [0:*]
+set offsets 0,0,graph 0.1,0
+plot 'scaling-graph.csv' skip 1 using 1:2 with lines notitle

script/generate_simulated_autoscaling_graph.rb

@@ -0,0 +1,23 @@
+require "csv"
+
+Time.use_zone "America/New_York" do
+  time = Time.zone.local(2025, 11, 24, 12)
+  data = []
+  while time < Time.zone.local(2025, 11, 25, 12)
+    data << [time, AutoscaleServersService.scaling_target_for(time)]
+    time += 15.minutes
+  end
+
+  puts "Writing simulated autoscaling data to scaling-graph.csv"
+
+  CSV.open("scaling-graph.csv", "w") do |csv|
+    csv << %w[Time Servers]
+    data.each { |row| csv << row }
+  end
+
+  puts "Plotting graph to scaling-graph.png"
+
+  system <<~SH
+    gnuplot -c ./script/generate_simulated_autoscaling_graph.gnuplot
+  SH
+end