From 2287957781b9c4485b92314cc3e85486bee84a36 Mon Sep 17 00:00:00 2001
From: Max Kadel <mkadel@princeton.edu>
Date: Wed, 13 Nov 2024 13:56:40 -0500
Subject: [PATCH] Add capistrano tasks to take a node off the load balancer.

Closes #154
---
 Gemfile                               |  3 +--
 Gemfile.lock                          |  4 ++--
 config/deploy.rb                      | 31 +++++++++++++++++++++++++++
 config/initializers/health_monitor.rb |  4 ++++
 4 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/Gemfile b/Gemfile
index 76425df..2fe6777 100644
--- a/Gemfile
+++ b/Gemfile
@@ -18,7 +18,7 @@ gem 'cancancan', '~> 3.3'
 gem 'faraday'
 
 gem 'devise'
-gem 'health-monitor-rails'
+gem 'health-monitor-rails', '12.4.0'
 gem 'omniauth'
 gem "omniauth-cas"
 gem "omniauth-rails_csrf_protection"
@@ -60,4 +60,3 @@ group :development do
   gem 'capistrano-passenger'
   gem 'ed25519'
 end
-
diff --git a/Gemfile.lock b/Gemfile.lock
index 0b8e8ea..aadb2e4 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -164,7 +164,7 @@ GEM
       activesupport (>= 6.1)
     hashdiff (1.1.0)
     hashie (5.0.0)
-    health-monitor-rails (12.2.0)
+    health-monitor-rails (12.4.0)
       railties (>= 6.1)
     i18n (1.14.6)
       concurrent-ruby (~> 1.0)
@@ -418,7 +418,7 @@ DEPENDENCIES
   ed25519
   factory_bot_rails
   faraday
-  health-monitor-rails
+  health-monitor-rails (= 12.4.0)
   jbuilder
   jquery-rails
   jquery-tablesorter
diff --git a/config/deploy.rb b/config/deploy.rb
index 263a4c4..ec21d7f 100644
--- a/config/deploy.rb
+++ b/config/deploy.rb
@@ -36,6 +36,37 @@
 # passenger-config restart-app which requires sudo access
 set :passenger_restart_with_touch, true
 
+namespace :application do
+  # You can/ should apply this command to a single host
+  # cap --hosts=repec-staging1.princeton.edu staging application:remove_from_nginx
+  desc "Marks the server(s) to be removed from the loadbalancer"
+  task :remove_from_nginx do
+    count = 0
+    on roles(:app) do
+      count += 1
+    end
+    if count > (roles(:app).length / 2)
+      raise "You must run this command on no more than half the servers utilizing the --hosts= switch"
+    end
+    on roles(:app) do
+      within release_path do
+        execute :touch, "public/remove-from-nginx"
+      end
+    end
+  end
+
+  # You can/ should apply this command to a single host
+  # cap --hosts=repec-staging1.princeton.edu staging application:serve_from_nginx
+  desc "Marks the server(s) to be added back to the loadbalancer"
+  task :serve_from_nginx do
+    on roles(:app) do
+      within release_path do
+        execute :rm, "-f public/remove-from-nginx"
+      end
+    end
+  end
+end
+
 # stop sprokets from crashing the production deploy
 Rake::Task["deploy:assets:backup_manifest"].clear_actions
 Rake::Task["deploy:assets:restore_manifest"].clear_actions 
diff --git a/config/initializers/health_monitor.rb b/config/initializers/health_monitor.rb
index 2764bea..d2f5f86 100644
--- a/config/initializers/health_monitor.rb
+++ b/config/initializers/health_monitor.rb
@@ -2,5 +2,9 @@
   HealthMonitor.configure do |config|
     # Make this health check available at /health
     config.path = :health
+
+    config.file_absence.configure do |file_config|
+      file_config.filename = "public/remove-from-nginx"
+    end
   end
 end