config: allow '/' in string args

CHANGELOG.md

@@ -32,6 +32,7 @@ BUG FIXES:
   * core: Variables are validated to not contain interpolations. [GH-180]
   * core: Key files for provisioning can now contain `~` and will be expanded
       to the user's home directory. [GH-179]
+  * core: The `file()` function can load files in sub-directories. [GH-213]
   * providers/aws: Fix issues around failing to read EIPs. [GH-122]
   * providers/aws: Autoscaling groups now register and export load
     balancers. [GH-207]

config/interpolate_walk.go

@@ -11,7 +11,7 @@ import (
 
 // 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

@@ -87,6 +87,22 @@ func TestInterpolationWalker_detect(t *testing.T) {
 				},
 			},
 		},
+
+		{
+			Input: map[string]interface{}{
+				"foo": `${file("foo/bar.txt")}`,
+			},
+			Result: []Interpolation{
+				&FunctionInterpolation{
+					Func: nil,
+					Args: []Interpolation{
+						&LiteralInterpolation{
+							Literal: "foo/bar.txt",
+						},
+					},
+				},
+			},
+		},
 	}
 
 	for i, tc := range cases {