Heroku vs YAML - Valid YAML is not being read by Heroku

Question

I've been playing with spaces all day and cannot, for the life of my, get my Heroku app to migrate the database. I keep getting

    rake aborted!
    YAML syntax error occurred while parsing /app/config/database.yml. Please note that YAML must be consistently indented using spaces. Tabs are not allowed. Error: (<unknown>): did not find expected key while parsing a block mapping at line 62 column 3

Which would be all fine and dandy as an error except I have run my YAML file through three different Validators and have been told by all of them that they are 'valid'.

Here's the edited YAML in question

# PostgreSQL. Versions 8.2 and up are supported.
#
# Install the pg driver:
#   gem install pg
# On OS X with Homebrew:
#   gem install pg -- --with-pg-config=/usr/local/bin/pg_config
# On 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'
#
default: &default
  adapter: postgresql
  encoding: unicode
  pool: 5

development:
  <<: *default
  database: coder-app_title
  username: postgres
  password: 123456
  host: localhost

  username: personal_username
  password: personal_password

# 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: 
   <<: *default   [[<< This is line 62.]]
   database: coder-add_title_test
   username: postgres
   password: 123456
   host: localhost

# As with config/secrets.yml, you never want to store sensitive information,
# like your database password, in your source code. If your source code is
# ever seen by anyone, they now have access to your database.
#
# Instead, provide the password as a unix environment variable when you boot
# the app. Read http://guides.rubyonrails.org/configuring.html#configuring-a-database
# for a full rundown on how to provide these environment variables in a
# production deployment.
#
# On Heroku and other platform providers, you may have a full connection URL
# available as an environment variable. For example:
#
#   DATABASE_URL="postgres://myuser:mypass@localhost/somedatabase"
#
# You can use this database configuration with:
#
   production:
     url: <%= ENV['DATABASE_URL'] %>
#
production:

Answer 1

The parser error is due to inconsistent indenting. I would recommend you use a decent text editor and use 2 spaces to indent the blocks.

I don't know what you have been using to validate the YAML which is not catching the error - copy pasting into a web based validator does not really work that well. Instead you can use the Ruby YAML module to parse the file:

# run `$ irb` from the root of project
require 'yaml'
YAML.parse(File.open('./config/development.rb'))

Also Heroku will write the production settings into the file so you should not have a production: section in your database.yml file.

This is a corrected version which parses properly:

# PostgreSQL. Versions 8.2 and up are supported.
#
# Install the pg driver:
#   gem install pg
# On OS X with Homebrew:
#   gem install pg -- --with-pg-config=/usr/local/bin/pg_config
# On 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'
#
default: &default
  adapter: postgresql
  encoding: unicode
  pool: 5

development:
  <<: *default
  database: coder-app_title
  username: postgres
  password: 123456
  host: localhost
  username: personal_username
  password: personal_password

# 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: 
  <<: *default
  database: coder-add_title_test
  username: postgres
  password: 123456
  host: localhost

# As with config/secrets.yml, you never want to store sensitive information,
# like your database password, in your source code. If your source code is
# ever seen by anyone, they now have access to your database.
#
# Instead, provide the password as a unix environment variable when you boot
# the app. Read http://guides.rubyonrails.org/configuring.html#configuring-a-database
# for a full rundown on how to provide these environment variables in a
# production deployment.
#
# NOTE. Heroku will write production settings in a post-commit hook. No configuration needed.