Added various profiling utilities

* Mini profiler for dev mode and for admins in production
* PgHero for dev mode and for admins in production
* Bullet for development
* pg_stat_statements for both the dev and prod setups

Author: dutow

Gemfile

@@ -74,4 +74,13 @@ group :development do
   # Capture emails in-browser during development
   gem "letter_opener"
   gem "letter_opener_web"
+
+  # Detect N+1 queries and unused eager loads
+  gem "bullet"
 end
+
+# Per-request SQL timings and flamegraphs (enabled for dev + admin users in prod)
+gem "rack-mini-profiler"
+
+# Mountable Postgres insights (uses pg_stat_statements)
+gem "pghero"

Gemfile.lock

@@ -86,6 +86,9 @@ GEM
     brakeman (7.1.1)
       racc
     builder (3.3.0)
+    bullet (8.1.0)
+      activesupport (>= 3.0.0)
+      uniform_notifier (~> 1.11)
     capybara (3.40.0)
       addressable
       matrix
@@ -264,6 +267,8 @@ GEM
     pg (1.6.2-aarch64-linux-musl)
     pg (1.6.2-x86_64-linux)
     pg (1.6.2-x86_64-linux-musl)
+    pghero (3.7.0)
+      activerecord (>= 7.1)
     pp (0.6.3)
       prettyprint
     prettyprint (0.2.0)
@@ -281,6 +286,8 @@ GEM
     raabro (1.4.0)
     racc (1.8.1)
     rack (3.2.4)
+    rack-mini-profiler (4.0.1)
+      rack (>= 1.2.0)
     rack-protection (4.2.1)
       base64 (>= 0.1.0)
       logger (>= 1.6.0)
@@ -436,6 +443,7 @@ GEM
     unicode-display_width (3.2.0)
       unicode-emoji (~> 4.1)
     unicode-emoji (4.1.0)
+    uniform_notifier (1.18.0)
     uri (1.1.1)
     useragent (0.16.11)
     version_gem (1.1.9)
@@ -467,6 +475,7 @@ DEPENDENCIES
   bcrypt (~> 3.1)
   bootsnap
   brakeman
+  bullet
   capybara
   debug
   factory_bot_rails
@@ -481,8 +490,10 @@ DEPENDENCIES
   omniauth-google-oauth2
   omniauth-rails_csrf_protection
   pg (~> 1.1)
+  pghero
   propshaft
   puma (>= 5.0)
+  rack-mini-profiler
   rails (~> 8.0.2)
   rspec-rails
   rubocop-rails-omakase

app/controllers/application_controller.rb

@@ -2,8 +2,9 @@ class ApplicationController < ActionController::Base
   allow_browser versions: :modern
 
   rescue_from ActiveRecord::RecordNotFound, with: :render_404
-  helper_method :current_user, :user_signed_in?
+  helper_method :current_user, :user_signed_in?, :current_admin?
   helper_method :activity_unread_count
+  before_action :authorize_mini_profiler
 
   private
 
@@ -21,10 +22,23 @@ def user_signed_in?
     current_user.present?
   end
 
+  def current_admin?
+    current_user&.admin?
+  end
+
   def require_authentication
     redirect_to new_session_path, alert: 'Please sign in' unless user_signed_in?
   end
 
+  def authorize_mini_profiler
+    return unless defined?(Rack::MiniProfiler)
+    if Rails.env.development?
+      Rack::MiniProfiler.authorize_request
+    elsif Rails.env.production? && current_admin?
+      Rack::MiniProfiler.authorize_request
+    end
+  end
+
   def activity_unread_count
     return 0 unless current_user
     @activity_unread_count ||= Activity.where(user: current_user, hidden: false, read_at: nil).count

bin/docker-entrypoint

@@ -6,6 +6,9 @@ if [ -z "${LD_PRELOAD+x}" ]; then
     export LD_PRELOAD
 fi
 
+# Ensure gems are installed when using a persistent bundle volume.
+bundle check || bundle install
+
 # If running the rails server (directly or via bin/dev), create or migrate the database
 if { [ "$1" = "./bin/rails" ] && [ "$2" = "server" ]; } || [ "$1" = "./bin/dev" ]; then
   ./bin/rails db:prepare

config/environments/development.rb

@@ -49,6 +49,22 @@
   # Append comments with runtime information tags to SQL queries in logs.
   config.active_record.query_log_tags_enabled = true
 
+  # Bullet: detect N+1 and eager loading issues.
+  config.after_initialize do
+    if defined?(Bullet)
+      Bullet.enable = true
+      Bullet.alert = false
+      Bullet.bullet_logger = true
+      Bullet.rails_logger = true
+      Bullet.add_footer = false
+    end
+  end
+
+  # rack-mini-profiler in development.
+  if defined?(Rack::MiniProfiler)
+    Rack::MiniProfiler.config.position = :right
+  end
+
   # Highlight code that enqueued background job in logs.
   config.active_job.verbose_enqueue_logs = true
 

config/initializers/mini_profiler.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+Rack::MiniProfiler.config.position = "right"
+Rack::MiniProfiler.config.skip_paths ||= []
+Rack::MiniProfiler.config.skip_paths += ["/up"]
+Rack::MiniProfiler.config.enable_hotwire_turbo_drive_support = true
+
+if Rails.env.development?
+  Rack::MiniProfiler.config.authorization_mode = :allow_all
+else
+  # Only allow signed-in admins in production; authorization happens later in ApplicationController.
+  Rack::MiniProfiler.config.authorization_mode = :allow_authorized
+end

config/routes.rb

@@ -53,6 +53,12 @@
 
   post "messages/:id/read", to: "messages#read", as: :read_message
 
+  if defined?(PgHero)
+    constraints AdminConstraint.new do
+      mount PgHero::Engine, at: "/pghero"
+    end
+  end
+
   if Rails.env.development?
     mount LetterOpenerWeb::Engine, at: "/letter_opener"
   end

deploy/README.md

@@ -44,6 +44,10 @@ This is a minimal, single-host setup for running Hackorum on a VPS (e.g., Hetzne
 5) Verify:
    - Browse to your domain; or `curl -f http://localhost:3000/up` from the host (`docker compose exec web ...` inside the network).
 
+## Observability
+- Query stats: pg_stat_statements is preloaded via the Postgres config and created on first init via `/docker-entrypoint-initdb.d/01_pg_stat_statements.sql`. For existing databases, run `CREATE EXTENSION IF NOT EXISTS pg_stat_statements;` once. PgHero is available at `/pghero` for signed-in admin users.
+- Request-level profiling: rack-mini-profiler is available; in production it renders only for signed-in admin users.
+
 ## Environment variables (deploy/.env)
 - `SECRET_KEY_BASE` (required)
 - `DATABASE_URL` (defaults to local Postgres via env interpolation)

deploy/docker-compose.yml

@@ -14,6 +14,7 @@ services:
       - pgwal:/var/lib/postgresql/wal-archive
       - pgbackups:/backups
       - ./postgres/postgresql.conf:/etc/postgresql/postgresql.conf:ro # copy from postgresql.conf.example
+      - ./postgres/init:/docker-entrypoint-initdb.d:ro
       - ./postgres/entrypoint.sh:/usr/local/bin/custom-entrypoint.sh:ro
     command:
       [

deploy/postgres/init/01_pg_stat_statements.sql

@@ -0,0 +1,2 @@
+-- Ensure pg_stat_statements is available in the default database.
+CREATE EXTENSION IF NOT EXISTS pg_stat_statements;