Use ENV['MONGODB_URI'] if available

README.md

@@ -173,6 +173,14 @@ Certain Ruby application servers work by forking, and it has long been necessary
 re-establish the child process's connection to the database after fork. But with the release
 of v1.3.0, the Ruby driver detects forking and reconnects automatically.
 
+## Environment variable `MONGODB_URI`
+
+`Mongo::Connection.new` and `Mongo::ReplSetConnection.new` will use <code>ENV["MONGODB_URI"]</code> if no other args are provided.
+
+The URI must fit this specification:
+
+    mongodb://[username:password@]host1[:port1][,host2[:port2],...[,hostN[:portN]]][/[database][?options]]
+
 ## String Encoding
 
 The BSON ("Binary JSON") format used to communicate with Mongo requires that

lib/mongo/connection.rb

@@ -32,6 +32,7 @@ class Connection
 
     Thread.abort_on_exception = true
 
+    DEFAULT_HOST = 'localhost'
     DEFAULT_PORT = 27017
     GENERIC_OPTS = [:ssl, :auths, :pool_size, :pool_timeout, :timeout, :op_timeout, :connect_timeout, :safe, :logger, :connect]
     CONNECTION_OPTS = [:slave_ok]
@@ -44,6 +45,8 @@ class Connection
 
     # Create a connection to single MongoDB instance.
     #
+    # If no args are provided, it will check <code>ENV["MONGODB_URI"]</code>.
+    #
     # You may specify whether connection to slave is permitted.
     # In all cases, the default host is "localhost" and the default port is 27017.
     #
@@ -76,7 +79,7 @@ class Connection
     #   connection attempt.
     # @option opts [Boolean] :ssl (false) If true, create the connection to the server using SSL.
     #
-    # @example localhost, 27017
+    # @example localhost, 27017 (or <code>ENV["MONGODB_URI"]</code> if available)
     #   Mongo::Connection.new
     #
     # @example localhost, 27017
@@ -93,9 +96,22 @@ class Connection
     # @raise [ReplicaSetConnectionError] This is raised if a replica set name is specified and the
     #   driver fails to connect to a replica set with that name.
     #
+    # @raise [MongoArgumentError] If called with no arguments and <code>ENV["MONGODB_URI"]</code> implies a replica set.
+    #
     # @core self.connections
     def initialize(host=nil, port=nil, opts={})
-      @host_to_try = format_pair(host, port)
+      if host.nil? and ENV.has_key?('MONGODB_URI')
+        parser = URIParser.new ENV['MONGODB_URI'], opts
+        if parser.replicaset?
+          raise MongoArgumentError, "Mongo::Connection.new called with no arguments, but ENV['MONGODB_URI'] implies a replica set."
+        end
+        opts = parser.connection_options
+        @host_to_try = [parser.host, parser.port]
+      elsif host.is_a?(String)
+        @host_to_try = [host, (port || DEFAULT_PORT).to_i]
+      else
+        @host_to_try = [DEFAULT_HOST, DEFAULT_PORT]
+      end
 
       # Host and port of current master.
       @host = @port = nil
@@ -143,8 +159,7 @@ def initialize(host=nil, port=nil, opts={})
     def self.multi(nodes, opts={})
       warn "Connection.multi is now deprecated and will be removed in v2.0. Please use ReplSetConnection.new instead."
 
-      nodes << opts
-      ReplSetConnection.new(*nodes)
+      ReplSetConnection.new(*(nodes+[opts]))
     end
 
     # Initialize a connection to MongoDB using the MongoDB URI spec:
@@ -155,21 +170,9 @@ def self.multi(nodes, opts={})
     # @param opts Any of the options available for Connection.new
     #
     # @return [Mongo::Connection, Mongo::ReplSetConnection]
-    def self.from_uri(string, extra_opts={})
-      uri = URIParser.new(string)
-      opts = uri.connection_options
-      opts.merge!(extra_opts)
-
-      if uri.nodes.length == 1
-        opts.merge!({:auths => uri.auths})
-        Connection.new(uri.nodes[0][0], uri.nodes[0][1], opts)
-      elsif uri.nodes.length > 1
-        nodes = uri.nodes.clone
-        nodes_with_opts = nodes << opts
-        ReplSetConnection.new(*nodes_with_opts)
-      else
-        raise MongoArgumentError, "No nodes specified. Please ensure that you've provided at least one node."
-      end
+    def self.from_uri(uri, extra_opts={})
+      parser = URIParser.new uri, extra_opts
+      parser.connection
     end
 
     # The host name used for this connection.
@@ -337,7 +340,7 @@ def drop_database(name)
     # @param [String] from_host host of the 'from' database.
     # @param [String] username username for authentication against from_db (>=1.3.x).
     # @param [String] password password for authentication against from_db (>=1.3.x).
-    def copy_database(from, to, from_host="localhost", username=nil, password=nil)
+    def copy_database(from, to, from_host=DEFAULT_HOST, username=nil, password=nil)
       oh = BSON::OrderedHash.new
       oh[:copydb]   = 1
       oh[:fromhost] = from_host
@@ -585,23 +588,8 @@ def setup(opts)
         write_logging_startup_message
       end
 
-      should_connect = opts.fetch(:connect, true)
-      connect if should_connect
-    end
-
-    ## Configuration helper methods
-
-    # Returns a host-port pair.
-    #
-    # @return [Array]
-    #
-    # @private
-    def format_pair(host, port)
-      case host
-        when String
-          [host, port ? port.to_i : DEFAULT_PORT]
-        when nil
-          ['localhost', DEFAULT_PORT]
+      if opts.fetch(:connect, true)
+        connect
       end
     end
 

lib/mongo/repl_set_connection.rb

@@ -29,6 +29,8 @@ class ReplSetConnection < Connection
 
     # Create a connection to a MongoDB replica set.
     #
+    # If no args are provided, it will check <code>ENV["MONGODB_URI"]</code>.
+    #
     # Once connected to a replica set, you can find out which nodes are primary, secondary, and
     # arbiters with the corresponding accessors: Connection#primary, Connection#secondaries, and
     # Connection#arbiters. This is useful if your application needs to connect manually to nodes other
@@ -78,6 +80,8 @@ class ReplSetConnection < Connection
     #
     # @see http://api.mongodb.org/ruby/current/file.REPLICA_SETS.html Replica sets in Ruby
     #
+    # @raise [MongoArgumentError] If called with no arguments and <code>ENV["MONGODB_URI"]</code> implies a direct connection.
+    #
     # @raise [ReplicaSetConnectionError] This is raised if a replica set name is specified and the
     #   driver fails to connect to a replica set with that name.
     def initialize(*args)
@@ -87,21 +91,30 @@ def initialize(*args)
         opts = {}
       end
 
-      unless args.length > 0
+      nodes = args
+
+      if nodes.empty? and ENV.has_key?('MONGODB_URI')
+        parser = URIParser.new ENV['MONGODB_URI'], opts
+        if parser.direct?
+          raise MongoArgumentError, "Mongo::ReplSetConnection.new called with no arguments, but ENV['MONGODB_URI'] implies a direct connection."
+        end
+        opts = parser.connection_options
+        nodes = parser.nodes
+      end
+
+      unless nodes.length > 0
         raise MongoArgumentError, "A ReplSetConnection requires at least one seed node."
       end
 
       # This is temporary until support for the old format is dropped
-      @seeds = []
-      if args.first.last.is_a?(Integer)
+      if nodes.first.last.is_a?(Integer)
         warn "Initiating a ReplSetConnection with seeds passed as individual [host, port] array arguments is deprecated."
         warn "Please specify hosts as an array of 'host:port' strings; the old format will be removed in v2.0"
-        @seeds = args
+        @seeds = nodes
       else
-        args.first.map do |host_port|
-          seed = host_port.split(":")
-          seed[1] = seed[1].to_i
-          seeds << seed
+        @seeds = nodes.first.map do |host_port|
+          host, port = host_port.split(":")
+          [ host, port.to_i ]
         end
       end