Govcloud support

[elerch]

There is a small change needed to support AWS Govcloud (and possibly Montreal region?). According to http://docs.aws.amazon.com/govcloud-us/latest/UserGuide/govcloud-ec2.html the bundles need a different cert to work successfully with ec2-bundle-image.

I got the script to work fine by adding --ec2cert $EC2_AMITOOL_HOME/etc/ec2/amitools/cert-ec2-gov.pem to the ec2-bundle-image command (note that $EC2_AMITOOL_HOME by default is not set, so the cert path is /etc/ec2/amitools/cert-ec2-gov.pem). Patch is below. It would be cool if the script detected govcloud and added the required ec2cert parameter. Given that my /etc/ec2/amitools/ directory also includes a cert for cn-north-1 this might be required for Montreal region as well, but I don't see documentation to that effect.

diff --git a/centos7-ami-builder.sh b/centos7-ami-builder.sh
index 57d025c..31238b4 100755
--- a/centos7-ami-builder.sh
+++ b/centos7-ami-builder.sh
@@ -420,7 +420,7 @@ undefine_hvm_dev() {
 bundle_ami() {
 	output "Bundling AMI for upload..."
 	RUBYLIB=/usr/lib/ruby/site_ruby/ ec2-bundle-image --privatekey $AWS_PRIVATE_KEY --cert $AWS_CERT \
-		--user $AWS_USER --image $AMI_IMG --prefix $AMI_NAME --destination $AMI_OUT --arch x86_64 || \
+		--user $AWS_USER --image $AMI_IMG --prefix $AMI_NAME --destination $AMI_OUT --arch x86_64 --ec2cert $EC2_AMITOOL_HOME/etc/ec2/amitools/cert-ec2-gov.pem || \
 		fatal "Failed to bundle image!"
 	AMI_MANIFEST=$AMI_OUT/$AMI_NAME.manifest.xml
 }