adding literal colon to interpolated regex

config/interpolate_walk.go

@@ -16,7 +16,7 @@ const InterpSplitDelim = `B780FFEC-B661-4EB8-9236-A01737AD98B6`
 
 // interpRegexp is a regexp that matches interpolations such as ${foo.bar}
 var interpRegexp *regexp.Regexp = regexp.MustCompile(
-	`(?i)(\$+)\{([\s*-.,\\/\(\)a-z0-9_"]+)\}`)
+	`(?i)(\$+)\{([\s*-.,\\/\(\):a-z0-9_"]+)\}`)
 
 // interpolationWalker implements interfaces for the reflectwalk package
 // (github.com/mitchellh/reflectwalk) that can be used to automatically

config/interpolate_walk_test.go

@@ -129,6 +129,25 @@ func TestInterpolationWalker_detect(t *testing.T) {
 				},
 			},
 		},
+
+		{
+			Input: map[string]interface{}{
+				"foo": `${concat("localhost", ":8080")}`,
+			},
+			Result: []Interpolation{
+				&FunctionInterpolation{
+					Func: nil,
+					Args: []Interpolation{
+						&LiteralInterpolation{
+							Literal: "localhost",
+						},
+						&LiteralInterpolation{
+							Literal: ":8080",
+						},
+					},
+				},
+			},
+		},
 	}
 
 	for i, tc := range cases {