Add capistrano tasks to take a node off the load balancer.

Closes #2546

Gemfile

@@ -22,7 +22,8 @@ gem 'faraday_middleware', '~> 1.0'
 gem 'ffi', '>= 1.9.25'
 gem 'friendly_id'
 gem 'gyoku', '~> 1.0'
-gem 'health-monitor-rails'
+# Pinning to 12.4.0 due to Rails 7.1 compatibility issue in 12.4.1
+gem 'health-monitor-rails', '12.4.0'
 gem 'high_voltage', '~> 3.0'
 gem 'honeybadger'
 gem 'human_languages', '~> 0.7'

Gemfile.lock

@@ -296,7 +296,7 @@ GEM
       rexml (~> 3.0)
     hashdiff (1.1.1)
     hashie (5.0.0)
-    health-monitor-rails (12.1.0)
+    health-monitor-rails (12.4.0)
       railties (>= 6.1)
     high_voltage (3.1.2)
     honeybadger (5.4.1)
@@ -701,7 +701,7 @@ DEPENDENCIES
   ffi (>= 1.9.25)
   friendly_id
   gyoku (~> 1.0)
-  health-monitor-rails
+  health-monitor-rails (= 12.4.0)
   high_voltage (~> 3.0)
   honeybadger
   human_languages (~> 0.7)

config/deploy.rb

@@ -61,6 +61,37 @@
   end
 end
 
+namespace :application do
+  # You can/ should apply this command to a single host
+  # cap --hosts=bibdata-staging1.lib.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=bibdata-staging1.lib.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
+
 after 'deploy:reverted', 'sidekiq:restart'
 after 'deploy:published', 'sidekiq:restart'
 after 'deploy:restart', 'sqs_poller:restart'

config/initializers/health_monitor.rb

@@ -10,7 +10,7 @@
 
     config.error_callback = proc do |e|
       Rails.logger.error "Health check failed with: #{e.message}"
-      Honeybadger.notify(e)
+      Honeybadger.notify(e) unless e.is_a?(HealthMonitor::Providers::FileAbsenceException)
     end
   end
 end