Rails - Postgres - could not connect to server: Connection refused (PG::ConnectionBad)

Question

Yesterday I've install Postgres and pgAdminIII, all worked correctly, but after reload it stopped working. After rails server I've got error message:

=> Booting Thin
=> Rails 3.2.13 application starting in development on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
Exiting
/home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:1216:in `initialize': could not connect to server: Connection refused (PG::ConnectionBad)
        Is the server running on host "localhost" (127.0.0.1) and accepting
        TCP/IP connections on port 5432?
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:1216:in `new'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:1216:in `connect'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:324:in `initialize'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:28:in `new'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:28:in `postgresql_connection'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:315:in `new_connection'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:325:in `checkout_new_connection'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:247:in `block (2 levels) in checkout'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:242:in `loop'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:242:in `block in checkout'
        from /home/home/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:239:in `checkout'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:102:in `block in connection'
        from /home/home/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:101:in `connection'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:410:in `retrieve_connection'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_specification.rb:171:in `retrieve_connection'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_specification.rb:145:in `connection'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/railtie.rb:88:in `block in <class:Railtie>'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/railties-3.2.13/lib/rails/initializable.rb:30:in `instance_exec'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/railties-3.2.13/lib/rails/initializable.rb:30:in `run'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/railties-3.2.13/lib/rails/initializable.rb:55:in `block in run_initializers'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/railties-3.2.13/lib/rails/initializable.rb:54:in `each'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/railties-3.2.13/lib/rails/initializable.rb:54:in `run_initializers'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/railties-3.2.13/lib/rails/application.rb:136:in `initialize!'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/railties-3.2.13/lib/rails/railtie/configurable.rb:30:in `method_missing'
        from /home/home/Projects/mostdance/config/environment.rb:5:in `<top (required)>'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:251:in `require'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:251:in `block in require'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:236:in `load_dependency'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-3.2.13/lib/active_support/dependencies.rb:251:in `require'
        from /home/home/Projects/mostdance/config.ru:3:in `block in <main>'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.4.5/lib/rack/builder.rb:51:in `instance_eval'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.4.5/lib/rack/builder.rb:51:in `initialize'
        from /home/home/Projects/mostdance/config.ru:in `new'
        from /home/home/Projects/mostdance/config.ru:in `<main>'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.4.5/lib/rack/builder.rb:40:in `eval'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.4.5/lib/rack/builder.rb:40:in `parse_file'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.4.5/lib/rack/server.rb:200:in `app'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/railties-3.2.13/lib/rails/commands/server.rb:46:in `app'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.4.5/lib/rack/server.rb:304:in `wrapped_app'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.4.5/lib/rack/server.rb:254:in `start'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/railties-3.2.13/lib/rails/commands/server.rb:70:in `start'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/railties-3.2.13/lib/rails/commands.rb:55:in `block in <top (required)>'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/railties-3.2.13/lib/rails/commands.rb:50:in `tap'
        from /home/home/.rvm/gems/ruby-1.9.3-p448/gems/railties-3.2.13/lib/rails/commands.rb:50:in `<top (required)>'
        from script/rails:6:in `require'
        from script/rails:6:in `<main>'

This is my database.yml file:

development:
  host: localhost
  adapter: postgresql
  encoding: unicode
  database: mydb
  pool: 5
  timeout: 5000
  username: postgres
  password: password
  min_messages: WARNING

test:
  host: localhost
  adapter: sqlite3
  database: db/test.sqlite3
  pool: 5
  timeout: 5000

production:
  adapter: postgresql
  encoding: unicode
  database: mydb
  pool: 5
  timeout: 5000
  username: postgres
  password: password
  host: 127.0.0.1
  port: 5432
  min_messages: WARNING

Also I try to run server Postgres:

su postgres /etc/init.d/postgresql start

Password: 
 * Starting PostgreSQL 9.1 database server                                                                                                                                                       * Use of uninitialized value $info{"pgdata"} in -d at /usr/bin/pg_ctlcluster line 331.
Use of uninitialized value $info{"pgdata"} in concatenation (.) or string at /usr/bin/pg_ctlcluster line 332.
Error:  is not accessible or does not exist

Also I don't know why, but now rails server put this error:

=> Booting Thin
=> Rails 3.2.13 application starting in development on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
Exiting
/home/home/.rvm/gems/ruby-1.9.3-p448/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:1216:in `initialize': FATAL:  Peer authentication failed for user "postgres" (PG::ConnectionBad)

Please, help me! If you need more information - write into comments and I will update my question

Answer 1

When I have had this issue in the past there are often a few things I can do to get it running, most of them seem simple, but I'm mighty forgetful --

sometimes I haven't actually created the DB after switching to postgres

bundle exec rake db:create

and then get all of my tables in there --

bundle exec rake db:migrate

other times I need to double check and make sure the PG gem is installed

gem install pg