PostgreSQL could not connect to: Unexpected error while processing request: could not connect to server: No such file or directory

Question

I am facing a very strange problem with PostgreSQL on Amazon EC2 below is the error:

Unexpected error while processing request: could not connect to server: No such file or directory
    Is the server running locally and accepting
    connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?

    /bundle/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql_adapter.rb:671:in `initialize'
    /bundle/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql_adapter.rb:671:in `new'
    /bundle/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql_adapter.rb:671:in `connect'
    /bundle/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql_adapter.rb:217:in `initialize'
    /bundle/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql_adapter.rb:37:in `new'
    /bundle/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/postgresql_adapter.rb:37:in `postgresql_connection'

I am able to log in from ssh through psql command to the AWS EC2 instance but when it is using my rails app it's not working, what could be the issue?

I am using AWS+EC2+Docker+RDS for my app deployment.

database.yml

default: &default
  adapter: postgresql
  encoding: unicode
  pool: 5
  timeout: 5000

development:
  <<: *default
  database: <%= Figaro.env.rds_db_name || Figaro.env.database_name %>
  host: <%= Figaro.env.rds_hostname || Figaro.env.database_host %>
  port: <%= Figaro.env.rds_port || Figaro.env.database_port %>
  username: <%= Figaro.env.rds_username || Figaro.env.database_username %>
  password: <%= Figaro.env.rds_password || Figaro.env.database_password %>

test:
  <<: *default
  database: cluetap_test

dev:
  <<: *default
  database: <%= Figaro.env.database_name %>

staging:
  <<: *default
  database: <%= Figaro.env.rds_db_name || Figaro.env.database_name %>
  host: <%= Figaro.env.rds_hostname || Figaro.env.database_host %>
  port: <%= Figaro.env.rds_port || Figaro.env.database_port %>
  username: <%= Figaro.env.rds_username || Figaro.env.database_username %>
  password: <%= Figaro.env.rds_password || Figaro.env.database_password %>

production:
  <<: *default
  database: <%= Figaro.env.rds_db_name || Figaro.env.database_name %>
  host: <%= Figaro.env.rds_hostname || Figaro.env.database_host %>
  port: <%= Figaro.env.rds_port || Figaro.env.database_port %>
  username: <%= Figaro.env.rds_username || Figaro.env.database_username %>
  password: <%= Figaro.env.rds_password || Figaro.env.database_password %>

Answer 1

这是安全组的问题，因此我已对其进行了更新，然后它可以正常工作。