Ruby (Rack) application could not be started

These are the possible causes:
  • There may be a syntax error in the application's code. Please check for such errors and fix them.
  • A required library may not installed. Please install all libraries that this application requires.
  • The application may not be properly configured. Please check whether all configuration files are written correctly, fix any incorrect configurations, and restart this application.
  • A service that the application relies on (such as the database server or the Ferret search engine server) may not have been started. Please start that service.
Further information about the error may have been written to the application's log file. Please check it in order to analyse the problem.
Error message:
Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) (Mysql2::Error)
Exception class:
PhusionPassenger::UnknownError
Application root:
/var/www/bulldozer/api/rails/bulldozer
Backtrace:
# File Line Location
0 /usr/local/lib/ruby/gems/1.8/gems/mysql2-0.2.13/lib/mysql2/client.rb 43 in `connect'
1 /usr/local/lib/ruby/gems/1.8/gems/mysql2-0.2.13/lib/mysql2/client.rb 43 in `initialize'
2 /usr/local/lib/ruby/gems/1.8/gems/mysql2-0.2.13/lib/active_record/connection_adapters/mysql2_adapter.rb 14 in `new'
3 /usr/local/lib/ruby/gems/1.8/gems/mysql2-0.2.13/lib/active_record/connection_adapters/mysql2_adapter.rb 14 in `mysql2_connection'
4 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/connection_adapters/abstract/connection_pool.rb 229 in `send'
5 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/connection_adapters/abstract/connection_pool.rb 229 in `new_connection'
6 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/connection_adapters/abstract/connection_pool.rb 237 in `checkout_new_connection'
7 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/connection_adapters/abstract/connection_pool.rb 191 in `checkout'
8 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/connection_adapters/abstract/connection_pool.rb 187 in `loop'
9 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/connection_adapters/abstract/connection_pool.rb 187 in `checkout'
10 /usr/local/lib/ruby/1.8/monitor.rb 242 in `synchronize'
11 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/connection_adapters/abstract/connection_pool.rb 186 in `checkout'
12 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/connection_adapters/abstract/connection_pool.rb 94 in `connection'
13 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/connection_adapters/abstract/connection_pool.rb 317 in `retrieve_connection'
14 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/connection_adapters/abstract/connection_specification.rb 97 in `retrieve_connection'
15 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/connection_adapters/abstract/connection_specification.rb 89 in `connection'
16 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/base.rb 1336 in `replace_bind_variables'
17 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/base.rb 1323 in `sanitize_sql_array'
18 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/base.rb 1230 in `sanitize_sql'
19 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/relation/query_methods.rb 223 in `send'
20 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/relation/query_methods.rb 223 in `build_where'
21 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/relation/query_methods.rb 76 in `where'
22 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/base.rb 447 in `__send__'
23 /usr/local/lib/ruby/gems/1.8/gems/activerecord-3.0.10/lib/active_record/base.rb 447 in `where'
24 /usr/local/lib/ruby/gems/1.8/gems/rails3_acts_as_paranoid-0.1.1/lib/rails3_acts_as_paranoid.rb 35 in `acts_as_paranoid'
25 /var/www/bulldozer/api/rails/bulldozer/app/models/course.rb 7
26 /usr/local/lib/ruby/gems/1.8/gems/activesupport-3.0.10/lib/active_support/dependencies.rb 239 in `require'
27 /usr/local/lib/ruby/gems/1.8/gems/activesupport-3.0.10/lib/active_support/dependencies.rb 239 in `require'
28 /usr/local/lib/ruby/gems/1.8/gems/activesupport-3.0.10/lib/active_support/dependencies.rb 227 in `load_dependency'
29 /usr/local/lib/ruby/gems/1.8/gems/activesupport-3.0.10/lib/active_support/dependencies.rb 239 in `require'
30 /usr/local/lib/ruby/gems/1.8/gems/activesupport-3.0.10/lib/active_support/dependencies.rb 346 in `require_or_load'
31 /usr/local/lib/ruby/gems/1.8/gems/activesupport-3.0.10/lib/active_support/dependencies.rb 300 in `depend_on'
32 /usr/local/lib/ruby/gems/1.8/gems/activesupport-3.0.10/lib/active_support/dependencies.rb 216 in `require_dependency'
33 /usr/local/lib/ruby/gems/1.8/gems/railties-3.0.10/lib/rails/engine.rb 138 in `eager_load!'
34 /usr/local/lib/ruby/gems/1.8/gems/railties-3.0.10/lib/rails/engine.rb 137 in `each'
35 /usr/local/lib/ruby/gems/1.8/gems/railties-3.0.10/lib/rails/engine.rb 137 in `eager_load!'
36 /usr/local/lib/ruby/gems/1.8/gems/railties-3.0.10/lib/rails/engine.rb 135 in `each'
37 /usr/local/lib/ruby/gems/1.8/gems/railties-3.0.10/lib/rails/engine.rb 135 in `eager_load!'
38 /usr/local/lib/ruby/gems/1.8/gems/railties-3.0.10/lib/rails/application.rb 108 in `eager_load!'
39 /usr/local/lib/ruby/gems/1.8/gems/railties-3.0.10/lib/rails/application/finisher.rb 41
40 /usr/local/lib/ruby/gems/1.8/gems/railties-3.0.10/lib/rails/initializable.rb 25 in `instance_exec'
41 /usr/local/lib/ruby/gems/1.8/gems/railties-3.0.10/lib/rails/initializable.rb 25 in `run'
42 /usr/local/lib/ruby/gems/1.8/gems/railties-3.0.10/lib/rails/initializable.rb 50 in `run_initializers'
43 /usr/local/lib/ruby/gems/1.8/gems/railties-3.0.10/lib/rails/initializable.rb 49 in `each'
44 /usr/local/lib/ruby/gems/1.8/gems/railties-3.0.10/lib/rails/initializable.rb 49 in `run_initializers'
45 /usr/local/lib/ruby/gems/1.8/gems/railties-3.0.10/lib/rails/application.rb 134 in `initialize!'
46 /usr/local/lib/ruby/gems/1.8/gems/railties-3.0.10/lib/rails/application.rb 77 in `send'
47 /usr/local/lib/ruby/gems/1.8/gems/railties-3.0.10/lib/rails/application.rb 77 in `method_missing'
48 /var/www/bulldozer/api/rails/bulldozer/config/environment.rb 5
49 config.ru 3 in `require'
50 config.ru 3
51 /usr/local/lib/ruby/gems/1.8/gems/rack-1.2.3/lib/rack/builder.rb 46 in `instance_eval'
52 /usr/local/lib/ruby/gems/1.8/gems/rack-1.2.3/lib/rack/builder.rb 46 in `initialize'
53 config.ru 1 in `new'
54 config.ru 1