Get memory data after booting app in production

Preload the app in `production` env, hit it with a single request, and
gather total gem memory consumption data using `derailed exec perf:mem`
from `derailed_benchmarks`. Present the result as MR metrics.

1 files changed, 11 insertions, 0 deletions

diff --git a/scripts/generate-memory-metrics-on-boot b/scripts/generate-memory-metrics-on-boot
new file mode 100755
index 00000000000..5197a8fcdcd
--- /dev/null
+++ b/scripts/generate-memory-metrics-on-boot
@@ -0,0 +1,11 @@
+#!/usr/bin/env ruby
+
+abort "usage: #{__FILE__} <memory_bundle_mem_file_name>" unless ARGV.length == 1
+memory_bundle_mem_file_name = ARGV.first
+
+full_report = File.open(memory_bundle_mem_file_name).read
+
+stats = /TOP: (?<total_mibs_str>.*) MiB/.match(full_report)
+abort 'failed to process the benchmark output' unless stats
+
+puts "total_memory_used_by_dependencies_on_boot_prod_env_mb #{stats[:total_mibs_str].to_f.round(1)}"