providers/aws: expand wildcard string lists

builtin/providers/aws/structure.go

@@ -1,6 +1,8 @@
 package aws
 
 import (
+	"strings"
+
 	"github.com/mitchellh/goamz/autoscaling"
 	"github.com/mitchellh/goamz/ec2"
 	"github.com/mitchellh/goamz/elb"
@@ -134,6 +136,14 @@ func flattenInstances(list []elb.Instance) []string {
 // Takes the result of flatmap.Expand for an array of strings
 // and returns a []string
 func expandStringList(configured []interface{}) []string {
+	// here we special case the * expanded lists. For example:
+	//
+	//	 instances = ["${aws_instance.foo.*.id}"]
+	//
+	if len(configured) == 1 && strings.Contains(configured[0].(string), ",") {
+		return strings.Split(configured[0].(string), ",")
+	}
+
 	vs := make([]string, 0, len(configured))
 	for _, v := range configured {
 		vs = append(vs, v.(string))

builtin/providers/aws/structure_test.go

@@ -90,3 +90,19 @@ func Test_expandStringList(t *testing.T) {
 	}
 
 }
+
+func Test_expandStringListWildcard(t *testing.T) {
+	stringList := expandStringList([]interface{}{"us-east-1a,us-east-1b"})
+	expected := []string{
+		"us-east-1a",
+		"us-east-1b",
+	}
+
+	if !reflect.DeepEqual(stringList, expected) {
+		t.Fatalf(
+			"Got:\n\n%#v\n\nExpected:\n\n%#v\n",
+			stringList,
+			expected)
+	}
+
+}