Rails: fe_sendauth: no password supplied (PG::ConnectionBad) from Ruby, but ok in Rails

Question

I'm having problems assessing a postgres database from straight ruby.

I've created a Postgres database using Rails

>rails new www --database=postgresql

using Rails 4.2.5 and Postgres is 9.4

It produces the following config/database.yml file.

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

development:
  <<: *default
  database: www_development

test:
  <<: *default
  database: www_test

production:
  <<: *default
  database: www_production
  username: www
  password: <%= ENV['WWW_DATABASE_PASSWORD'] %>

I can run rails server, db:drop, db:create and db:migrate fine.

I can also access the database fine with psql

>psql www_development

But when I run the following app.rb from a non Rails project directory, I get a fe_sendauth: no password supplied (PG::ConnectionBad) error message.

It's clearly not a Rails issue. I've either missed something in my ruby or Postgres need a tweek to handle some difference between Rails and pure Ruby [that I'm not aware off]. I've also included Postgres' pg_hba.conf file.

At wits end trying to figure this one out. Any help would be much appreciated.

app.rb

require 'yaml'
require 'active_record'
require 'pg'

ActiveRecord::Base.establish_connection(
  adapter:  'postgresql',
  host:     'localhost',
  database: 'www_development',
)

/etc/postgresql/9.4/main/pg_hba.conf

# TYPE  DATABASE        USER            ADDRESS                 METHOD

local   all             postgres                                peer
local   all             all                                     peer
host    all             all             127.0.0.1/32            md5
host    all             all             ::1/128                 md5

Answer 1

You don't specify neither username, no password in your ActiveRecord::Base.establish_connection(. I assume you want to use some SUPERUSER without password for www_development database - right?

as per documentation peer auth does

Obtain the client's operating system user name from the operating system and check if it matches the requested database user name.

That is why if you can psql without password, you should be able run app.rb with same OS user and environment without password. If you can't, then app.rb tries to connect with different username or so...

Options:

1. put username: postgres to ActiveRecord::Base.establish_connection(

2. change local all all peer to local all all trust