Class: HerokuExternalDb::Configuration

Inherits:
Object
  • Object
show all
Defined in:
lib/heroku_external_db.rb

Overview

Represents an ActiveRecord database configuration to be used in a Heroku app. This configuration consists of at least one environment variable, and possibly several:

  • [PREFIX]_DATABASE_URL - the Heroku-style DATABASE_URL to connect to. Required.

  • [PREFIX]_DATABASE_CA - the filename of a SSL certificate file which will be configured as the :sslca for the database. Useful for encrypted MySQL, e.g.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(env_prefix, configuration_name) ⇒ Configuration

Returns a new instance of Configuration.



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# File 'lib/heroku_external_db.rb', line 43

def initialize(env_prefix, configuration_name)
  @env_prefix = env_prefix
  @configuration_name = configuration_name
end

Instance Attribute Details

#ca_path ⇒ Object

The path in which your SSL CA certificates are stored. By default, this is [Rails app root]/config/ca.



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# File 'lib/heroku_external_db.rb', line 50

def ca_path
  @ca_path ||= ca_path_from_rails_root
end

#configuration_name ⇒ Object (readonly)

The ActiveRecord configuration that will be set up. Typically this should be the same as your RAILS_ENV environment variable, but some apps may have multiple database connections with different names.



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# File 'lib/heroku_external_db.rb', line 40

def configuration_name
  @configuration_name
end

#env_prefix ⇒ Object (readonly)

Each HerokuExternalDb must have a unique prefix for its environment variables. For example, if the prefix was set to CRAZY, then the database URL would be taken from CRAZY_DATABASE_URL, and the CA filename would be taken from CRAZY_DATABASE_CA, if it existed.

In typical usage, the prefix will be EXTERNAL by default.



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# File 'lib/heroku_external_db.rb', line 35

def env_prefix
  @env_prefix
end

Instance Method Details

#db_ca_configuration(ca_filename) ⇒ Object

Returns a partial ActiveRecord configuration hash for the given SSL CA certificate. Checks to make sure the given filename actually exists, and raises an error if it does not.



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# File 'lib/heroku_external_db.rb', line 79

def db_ca_configuration(ca_filename)
  return {} unless ca_filename

  raise "ca_path for #{ca_filename} cannot be determined from Rails root; please set it explicitly" unless ca_path
  
  ca_filepath = File.join(ca_path, ca_filename)
  raise "CA file #{ca_filepath} does not exist!" unless File.exists?(ca_filepath)

  return { :sslca => ca_filepath }
end

#db_config ⇒ Object

Returns an ActiveRecord configuration hash based on the environment variables.



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# File 'lib/heroku_external_db.rb', line 91

def db_config
  @db_config ||= begin 
    raise "ENV['#{env_prefix}_DATABASE_URL'] expected but not found!" unless ENV["#{env_prefix}_DATABASE_URL"]
    config = parse_db_uri(ENV["#{env_prefix}_DATABASE_URL"])

    if ENV["#{env_prefix}_DATABASE_CA"]
      config.merge!(db_ca_configuration(ENV["#{env_prefix}_DATABASE_CA"]))
    end
  
    config
  end
end

#parse_db_uri(db_uri) ⇒ Object

Parse a Heroku-style database URI and return an ActiveRecord configuration hash based on it. Format is as follows:

<adapter>://[<username>[:<password>]]@<host>[:<port>]/<database>



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# File 'lib/heroku_external_db.rb', line 58

def parse_db_uri(db_uri)
  uri = URI.parse(db_uri)

  db_config = {
    :adapter => uri.scheme,
    :database => uri.path[1..-1],
    :host => uri.host
  }

  if uri.user
    db_config[:username] = uri.user
    db_config[:password] = uri.password if uri.password
  end
  db_config[:port] = uri.port if uri.port

  db_config
end

#setup! ⇒ Object

Installs an ActiveRecord configuration based on the environment variables, and makes an initial connection to the database. (This flushes out the connection pool if a different connection has already been established, and tests to make sure we can actually connect.)



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# File 'lib/heroku_external_db.rb', line 108

def setup!
  ActiveRecord::Base.configurations[configuration_name] = db_config
  ActiveRecord::Base.establish_connection(configuration_name).connection
  self
end