add option to associate public ip with instance

README.md

@@ -60,6 +60,20 @@ For specific default values, please consult [amis.json][amis_json].
 
 ## <a name="config"></a> Configuration
 
+### <a name="config-associate-public-ip"></a> associate\_public\_ip
+
+AWS does not automatically allocate public IP addresses for instances created
+within non-default [subnets][subnet_docs]. Set this option to `true` to force
+allocation of a public IP and associate it with the launched instance.
+
+If you set this option to `false` when launching into a non-default
+[subnet][subnet_docs], Test Kitchen will be unable to communicate with the
+instance unless you have a VPN connection to your
+[Virtual Private Cloud][vpc_docs].
+
+The default is `true` if you have configured a [subnet_id](#config-subnet-id),
+or `false` otherwise.
+
 ### <a name="config-az"></a> availability\_zone
 
 **Required** The AWS [availability zone][region_docs] to use.
@@ -145,7 +159,6 @@ The place from which to derive the hostname for communicating with the instance.
 
 The default is unset.
 
-
 ### <a name="config-region"></a> region
 
 **Required** The AWS [region][region_docs] to use.
@@ -290,3 +303,4 @@ Apache 2.0 (see [LICENSE][license])
 [kitchenci]:        http://kitchen.ci/
 [region_docs]:      http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-regions-availability-zones.html
 [subnet_docs]:      http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ec2-subnet.html
+[vpc_docs]:         http://docs.aws.amazon.com/AmazonVPC/latest/GettingStartedGuide/ExerciseOverview.html

lib/kitchen/driver/ec2.rb

@@ -61,6 +61,10 @@ class Ec2 < Kitchen::Driver::SSHBase
 
       default_config :interface, nil
 
+      default_config :associate_public_ip do |driver|
+        driver.default_public_ip_association
+      end
+
       required_config :aws_access_key_id
       required_config :aws_secret_access_key
       required_config :aws_ssh_key_id
@@ -101,6 +105,10 @@ def default_username
         amis['usernames'][instance.platform.name] || 'root'
       end
 
+      def default_public_ip_association
+        !!config[:subnet_id]
+      end
+
       private
 
       def connection
@@ -127,6 +135,7 @@ def create_server
           :key_name                  => config[:aws_ssh_key_id],
           :subnet_id                 => config[:subnet_id],
           :iam_instance_profile_name => config[:iam_profile_name],
+          :associate_public_ip       => config[:associate_public_ip]
         )
       end
 
@@ -141,6 +150,7 @@ def debug_server_config
         debug("ec2:key_name '#{config[:aws_ssh_key_id]}'")
         debug("ec2:subnet_id '#{config[:subnet_id]}'")
         debug("ec2:iam_profile_name '#{config[:iam_profile_name]}'")
+        debug("ec2:associate_public_ip '#{config[:associate_public_ip]}'")
       end
 
       def amis