我正在使用ruby 2.2.2（运行ubuntu 16.04）开发Rails 4.2.3项目。它工作正常，但经过一段时间重新访问后，我无法服务。我试过搜索，但所有情况似乎没有帮助。这是错误日志：
bigzoo@bigzoo:~/Documents/projects/proj$ rs
=> Booting Puma
=> Rails 4.2.3 application starting in development on http://localhost:3000
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
Exiting
/home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/postgresql_adapter.rb:655:in `initialize': could not translate host name "postgres" to address: Name or service not known (PG::ConnectionBad)
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/postgresql_adapter.rb:655:in `new'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/postgresql_adapter.rb:655:in `connect'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/postgresql_adapter.rb:242:in `initialize'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/postgresql_adapter.rb:44:in `new'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/postgresql_adapter.rb:44:in `postgresql_connection'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:438:in `new_connection'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:448:in `checkout_new_connection'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:422:in `acquire_connection'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:349:in `block in checkout'
from /home/bigzoo/.rbenv/versions/2.2.2/lib/ruby/2.2.0/monitor.rb:211:in `mon_synchronize'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:348:in `checkout'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:263:in `block in connection'
from /home/bigzoo/.rbenv/versions/2.2.2/lib/ruby/2.2.0/monitor.rb:211:in `mon_synchronize'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:262:in `connection'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:571:in `retrieve_connection'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_handling.rb:113:in `retrieve_connection'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/connection_handling.rb:87:in `connection'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/querying.rb:39:in `find_by_sql'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/relation.rb:638:in `exec_queries'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/relation.rb:514:in `load'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/relation.rb:243:in `to_a'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activerecord-4.2.3/lib/active_record/relation/delegation.rb:46:in `map'
from /home/bigzoo/Documents/projects/proj/app/admin/product.rb:62:in `block in <top (required)>'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/bundler/gems/activeadmin-21f76b1faf65/lib/active_admin/dsl.rb:15:in `instance_exec'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/bundler/gems/activeadmin-21f76b1faf65/lib/active_admin/dsl.rb:15:in `run_registration_block'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/bundler/gems/activeadmin-21f76b1faf65/lib/active_admin/namespace.rb:223:in `parse_registration_block'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/bundler/gems/activeadmin-21f76b1faf65/lib/active_admin/namespace.rb:48:in `register'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/bundler/gems/activeadmin-21f76b1faf65/lib/active_admin/application.rb:154:in `register'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/bundler/gems/activeadmin-21f76b1faf65/lib/active_admin.rb:75:in `register'
from /home/bigzoo/Documents/projects/proj/app/admin/product.rb:1:in `<top (required)>'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:268:in `load'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:268:in `block in load'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:240:in `load_dependency'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:268:in `load'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/bundler/gems/activeadmin-21f76b1faf65/lib/active_admin/application.rb:212:in `block in load'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/bundler/gems/activeadmin-21f76b1faf65/lib/active_admin/error.rb:41:in `capture'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/bundler/gems/activeadmin-21f76b1faf65/lib/active_admin/application.rb:212:in `load'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/bundler/gems/activeadmin-21f76b1faf65/lib/active_admin/application.rb:204:in `block in load!'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/bundler/gems/activeadmin-21f76b1faf65/lib/active_admin/application.rb:204:in `each'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/bundler/gems/activeadmin-21f76b1faf65/lib/active_admin/application.rb:204:in `load!'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/bundler/gems/activeadmin-21f76b1faf65/lib/active_admin/application.rb:226:in `routes'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/bundler/gems/activeadmin-21f76b1faf65/lib/active_admin.rb:79:in `routes'
from /home/bigzoo/Documents/projects/proj/config/routes.rb:20:in `block in <top (required)>'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/actionpack-4.2.3/lib/action_dispatch/routing/route_set.rb:434:in `instance_exec'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/actionpack-4.2.3/lib/action_dispatch/routing/route_set.rb:434:in `eval_block'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/actionpack-4.2.3/lib/action_dispatch/routing/route_set.rb:412:in `draw'
from /home/bigzoo/Documents/projects/proj/config/routes.rb:1:in `<top (required)>'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:268:in `load'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:268:in `block in load'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:240:in `load_dependency'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:268:in `load'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/application/routes_reloader.rb:40:in `block in load_paths'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/application/routes_reloader.rb:40:in `each'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/application/routes_reloader.rb:40:in `load_paths'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/application/routes_reloader.rb:16:in `reload!'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/application/routes_reloader.rb:26:in `block in updater'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/file_update_checker.rb:75:in `call'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/file_update_checker.rb:75:in `execute'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/application/routes_reloader.rb:27:in `updater'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/application/routes_reloader.rb:7:in `execute_if_updated'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/application/finisher.rb:69:in `block in <module:Finisher>'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/initializable.rb:30:in `instance_exec'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/initializable.rb:30:in `run'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/initializable.rb:55:in `block in run_initializers'
from /home/bigzoo/.rbenv/versions/2.2.2/lib/ruby/2.2.0/tsort.rb:226:in `block in tsort_each'
from /home/bigzoo/.rbenv/versions/2.2.2/lib/ruby/2.2.0/tsort.rb:348:in `block (2 levels) in each_strongly_connected_component'
from /home/bigzoo/.rbenv/versions/2.2.2/lib/ruby/2.2.0/tsort.rb:429:in `each_strongly_connected_component_from'
from /home/bigzoo/.rbenv/versions/2.2.2/lib/ruby/2.2.0/tsort.rb:347:in `block in each_strongly_connected_component'
from /home/bigzoo/.rbenv/versions/2.2.2/lib/ruby/2.2.0/tsort.rb:345:in `each'
from /home/bigzoo/.rbenv/versions/2.2.2/lib/ruby/2.2.0/tsort.rb:345:in `call'
from /home/bigzoo/.rbenv/versions/2.2.2/lib/ruby/2.2.0/tsort.rb:345:in `each_strongly_connected_component'
from /home/bigzoo/.rbenv/versions/2.2.2/lib/ruby/2.2.0/tsort.rb:224:in `tsort_each'
from /home/bigzoo/.rbenv/versions/2.2.2/lib/ruby/2.2.0/tsort.rb:203:in `tsort_each'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/initializable.rb:54:in `run_initializers'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/application.rb:352:in `initialize!'
from /home/bigzoo/Documents/projects/proj/config/environment.rb:5:in `<top (required)>'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:274:in `require'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:274:in `block in require'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:240:in `load_dependency'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:274:in `require'
from /home/bigzoo/Documents/projects/proj/config.ru:3:in `block in <main>'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/rack-1.6.5/lib/rack/builder.rb:55:in `instance_eval'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/rack-1.6.5/lib/rack/builder.rb:55:in `initialize'
from /home/bigzoo/Documents/projects/proj/config.ru:in `new'
from /home/bigzoo/Documents/projects/proj/config.ru:in `<main>'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/rack-1.6.5/lib/rack/builder.rb:49:in `eval'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/rack-1.6.5/lib/rack/builder.rb:49:in `new_from_string'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/rack-1.6.5/lib/rack/builder.rb:40:in `parse_file'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/rack-1.6.5/lib/rack/server.rb:299:in `build_app_and_options_from_config'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/rack-1.6.5/lib/rack/server.rb:208:in `app'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/commands/server.rb:61:in `app'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/rack-1.6.5/lib/rack/server.rb:336:in `wrapped_app'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/commands/server.rb:139:in `log_to_stdout'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/commands/server.rb:78:in `start'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/commands/commands_tasks.rb:80:in `block in server'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/commands/commands_tasks.rb:75:in `tap'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/commands/commands_tasks.rb:75:in `server'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/railties-4.2.3/lib/rails/commands.rb:17:in `<top (required)>'
from /home/bigzoo/Documents/projects/proj/bin/rails:8:in `require'
from /home/bigzoo/Documents/projects/proj/bin/rails:8:in `<top (required)>'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/spring-1.3.6/lib/spring/client/rails.rb:28:in `load'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/spring-1.3.6/lib/spring/client/rails.rb:28:in `call'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/spring-1.3.6/lib/spring/client/command.rb:7:in `call'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/spring-1.3.6/lib/spring/client.rb:26:in `run'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/spring-1.3.6/bin/spring:48:in `<top (required)>'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/spring-1.3.6/lib/spring/binstub.rb:11:in `load'
from /home/bigzoo/Documents/projects/proj/.bundle/ruby/2.2.0/gems/spring-1.3.6/lib/spring/binstub.rb:11:in `<top (required)>'
from /home/bigzoo/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
from /home/bigzoo/.rbenv/versions/2.2.2/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
from /home/bigzoo/Documents/projects/proj/bin/spring:13:in `<top (required)>'
from bin/rails:3:in `load'
from bin/rails:3:in `<main>'
唯一的问题似乎是连接到postgres。
PS。我已经尝试过运行unset DATABASE_URL，如果有人感到被迫建议那样做。
额外信息：
bigzoo@bigzoo:~/Documents/projects/proj$ sudo netstat -atpn | grep 5432
[sudo] password for bigzoo:
tcp 0 0 127.0.0.1:5432 0.0.0.0:* LISTEN 1744/postgres
将下面的行添加到/ etc / hosts就可以了。
127.0.0.1 postgres
做了伎俩。
Rails使用主机名postgres并将其留给系统，以根据需要将postgres引导到主机和端口。如果由于某种原因它不起作用，则上面的行允许映射。
积分@mudasobwa。
PS。要编辑/ etc / hosts，只需键入（在控制台中）
sudo nano /etc/hosts
打开它并添加该行。
这件事发生在我经常使用的容器上。它只是随机开始抛出这个错误而不是解决。
我最终解决了它
docker system prune --volumes
没有卷标志运行它没有解决它。