我曾多次尝试使用 nginx 和 unicorn 在 ec2 实例上设置我的 rails 应用程序。我发现 nginx 和 unicorn 都设置正确；但是，在两台机器上，我的 rails 应用程序都不想在生产环境中启动。尝试在生产中启动的输出是：
/Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_specification.rb:47:in `resolve_hash_connection': database configuration does not specify adapter (ActiveRecord::AdapterNotSpecified)
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_specification.rb:41:in `resolve_string_connection'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_specification.rb:25:in `spec'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_specification.rb:129:in `establish_connection'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/railtie.rb:82:in `block (2 levels) in <class:Railtie>'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activesupport-3.2.8/lib/active_support/lazy_load_hooks.rb:36:in `instance_eval'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activesupport-3.2.8/lib/active_support/lazy_load_hooks.rb:36:in `execute_hook'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activesupport-3.2.8/lib/active_support/lazy_load_hooks.rb:26:in `block in on_load'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activesupport-3.2.8/lib/active_support/lazy_load_hooks.rb:25:in `each'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activesupport-3.2.8/lib/active_support/lazy_load_hooks.rb:25:in `on_load'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/railtie.rb:74:in `block in <class:Railtie>'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/initializable.rb:30:in `instance_exec'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/initializable.rb:30:in `run'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/initializable.rb:55:in `block in run_initializers'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/initializable.rb:54:in `each'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/initializable.rb:54:in `run_initializers'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/application.rb:136:in `initialize!'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/railtie/configurable.rb:30:in `method_missing'
from /Users/benvreed/Documents/rubydev/StudyPublic/config/environment.rb:5:in `<top (required)>'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `require'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `block in require'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:236:in `load_dependency'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `require'
from /Users/benvreed/Documents/rubydev/StudyPublic/config.ru:4:in `block in <main>'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/builder.rb:51:in `instance_eval'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/builder.rb:51:in `initialize'
from /Users/benvreed/Documents/rubydev/StudyPublic/config.ru:1:in `new'
from /Users/benvreed/Documents/rubydev/StudyPublic/config.ru:1:in `<main>'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/builder.rb:40:in `eval'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/builder.rb:40:in `parse_file'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/server.rb:200:in `app'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/commands/server.rb:46:in `app'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/server.rb:301:in `wrapped_app'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/server.rb:252:in `start'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/commands/server.rb:70:in `start'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/commands.rb:55:in `block in <top (required)>'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/commands.rb:50:in `tap'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/commands.rb:50:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'
虽然，我清楚地在我的database.yml文件中指定了 postgresql 适配器：
# PostgreSQL. Versions 8.2 and up are supported.
#
# Install the pg driver:
# gem install pg
# On Mac OS X with macports:
# gem install pg -- --with-pg-config=/opt/local/lib/postgresql84/bin/pg_config
# On Windows:
# gem install pg
# Choose the win32 build.
# Install PostgreSQL and put its /bin directory on your path.
#
# Configure Using Gemfile
# gem 'pg'
#
development:
adapter: postgresql
encoding: unicode
host: localhost
database: study_development
pool: 5
# Connect on a TCP socket. Omitted by default since the client uses a
# domain socket that doesn't need configuration. Windows does not have
# domain sockets, so uncomment these lines.
#host: localhost
#port: 5432
# Schema search path. The server defaults to $user,public
#schema_search_path: myapp,sharedapp,public
# Minimum log levels, in increasing order:
# debug5, debug4, debug3, debug2, debug1,
# log, notice, warning, error, fatal, and panic
# The server defaults to notice.
#min_messages: warning
# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
adapter: postgresql
encoding: unicode
host: localhost
database: study_test
pool: 5
production:
adapter: postgresql
encoding: unicode
host: localhost
database: study_production
pool: 5
真正奇怪的是它在开发和测试环境中都成功运行。我检查了 StackOverflow 上的其他问题，大多数人都说这是一个间距问题；但是，我已经多次重做database.yml文件，结果相同。
我的 unicorn 和 nginx 文件是标准配置。
任何帮助将不胜感激。在运行之前，我一直处于静止状态。提前致谢。
RAILS_ENV
通过执行来使用 Rails 控制台时RAILS_ENV=production rails c，运行RAILS_ENV会产生：
NameError: uninitialized constant RAILS_ENV
from (irb):1
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/commands/console.rb:47:in `start'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/commands/console.rb:8:in `start'
from /Users/benvreed/.rbenv/versions/1.9.3-p327/lib/ruby/gems/1.9.1/gems/railties-3.2.8/lib/rails/commands.rb:41:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'
Rails.env 产生：
=> "production"