Add bootchecking for rails applications

lib/language_pack/helpers/rails_bootcheck.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+class LanguagePack::Helpers::RailsBootcheck
+  include LanguagePack::ShellHelpers
+
+  def initialize(timeout = 65)
+    @timeout = timeout
+  end
+
+  def call
+    return unless opted_in? && !opted_out?
+
+    topic("Bootchecking rails application")
+
+    process = ProcessSpawn.new(
+      "rails runner 'puts Rails.env'",
+      user_env: true,
+      timeout:  @timeout,
+      file:     "./.heroku/ruby/compile/rails_bootcheck.txt"
+    )
+
+    if process.timeout?
+      failure("timeout", process.output)
+    elsif !process.success?
+      failure("failure", process.output)
+    end
+  end
+
+  private
+
+  def failure(type, output)
+    message = String.new("Bootchecking rails application #{type}\n")
+    message << "set HEROKU_RAILS_BOOTCHECK_DISABLE=1 to disable this feature\n"
+
+    if !output.empty?
+      message << "\n"
+      message << output
+    end
+
+    error(message)
+  end
+
+  def opted_in?
+    env("HEROKU_RAILS_BOOTCHECK_ENABLE")
+  end
+
+  def opted_out?
+    env("HEROKU_RAILS_BOOTCHECK_DISABLE")
+  end
+end

lib/language_pack/rails2.rb

@@ -1,6 +1,7 @@
 require "fileutils"
 require "language_pack"
 require "language_pack/rack"
+require "language_pack/helpers/rails_bootcheck"
 
 # Rails 2 Language Pack. This is for any Rails 2.x apps.
 class LanguagePack::Rails2 < LanguagePack::Ruby
@@ -19,6 +20,7 @@ def self.use?
   def initialize(*args)
     super(*args)
     @rails_runner = LanguagePack::Helpers::RailsRunner.new
+    @bootcheck = LanguagePack::Helpers::RailsBootcheck.new
   end
 
   def name
@@ -29,7 +31,7 @@ def default_env_vars
     {
       "RAILS_ENV" => "production",
       "RACK_ENV" => "production"
-    }
+    }.merge(bootcheck_env_vars)
   end
 
   def default_config_vars
@@ -60,6 +62,7 @@ def compile
     instrument "rails2.compile" do
       install_plugins
       super
+      @bootcheck.call
     end
   end
 
@@ -106,4 +109,11 @@ def setup_profiled(*args)
     end
   end
 
+  def bootcheck_env_vars
+    value = env("HEROKU_RAILS_BOOTCHECK_ENABLE")
+
+    return {} unless value || new_app?
+
+    { "HEROKU_RAILS_BOOTCHECK_ENABLE" => value || "1" }
+  end
 end