Use DescribeRegions for aws region validation

builder/amazon/common/regions.go

@@ -1,29 +1,26 @@
 package common
 
-// aws ec2 describe-regions --query 'Regions[].{Name:RegionName}' --output text | sed 's/\(.*\)/"\1",/' | sort
+import (
+	"github.com/aws/aws-sdk-go/aws/session"
+	"github.com/aws/aws-sdk-go/service/ec2"
+)
+
 func listEC2Regions() []string {
-	return []string{
-		"ap-northeast-1",
-		"ap-northeast-2",
-		"ap-northeast-3",
-		"ap-south-1",
-		"ap-southeast-1",
-		"ap-southeast-2",
-		"ca-central-1",
-		"eu-central-1",
-		"eu-west-1",
-		"eu-west-2",
-		"eu-west-3",
-		"sa-east-1",
-		"us-east-1",
-		"us-east-2",
-		"us-west-1",
-		"us-west-2",
-		// not part of autogenerated list
-		"us-gov-west-1",
-		"cn-north-1",
-		"cn-northwest-1",
+	var regions []string
+	// append regions that are not part of autogenerated list
+	regions = append(regions, "us-gov-west-1", "cn-north-1", "cn-northwest-1")
+
+	sess := session.Must(session.NewSessionWithOptions(session.Options{
+		SharedConfigState: session.SharedConfigEnable,
+	}))
+
+	ec2conn := ec2.New(sess)
+	resultRegions, _ := ec2conn.DescribeRegions(nil)
+	for _, region := range resultRegions.Regions {
+		regions = append(regions, *region.RegionName)
 	}
+
+	return regions
 }
 
 // ValidateRegion returns true if the supplied region is a valid AWS