template/interpolate: add template_path

template/interpolate/funcs.go

@@ -23,12 +23,13 @@ func init() {
 
 // Funcs are the interpolation funcs that are available within interpolations.
 var FuncGens = map[string]FuncGenerator{
-	"env":       funcGenEnv,
-	"isotime":   funcGenIsotime,
-	"pwd":       funcGenPwd,
-	"timestamp": funcGenTimestamp,
-	"uuid":      funcGenUuid,
-	"user":      funcGenUser,
+	"env":           funcGenEnv,
+	"isotime":       funcGenIsotime,
+	"pwd":           funcGenPwd,
+	"template_path": funcGenTemplatePath,
+	"timestamp":     funcGenTimestamp,
+	"uuid":          funcGenUuid,
+	"user":          funcGenUser,
 
 	"upper": funcGenPrimitive(strings.ToUpper),
 	"lower": funcGenPrimitive(strings.ToLower),
@@ -92,6 +93,16 @@ func funcGenPwd(ctx *Context) interface{} {
 	}
 }
 
+func funcGenTemplatePath(ctx *Context) interface{} {
+	return func() (string, error) {
+		if ctx == nil || ctx.TemplatePath == "" {
+			return "", errors.New("template path not available")
+		}
+
+		return ctx.TemplatePath, nil
+	}
+}
+
 func funcGenTimestamp(ctx *Context) interface{} {
 	return func() string {
 		return strconv.FormatInt(InitTime.Unix(), 10)

template/interpolate/funcs_test.go

@@ -116,6 +116,33 @@ func TestFuncPwd(t *testing.T) {
 	}
 }
 
+func TestFuncTemplatePath(t *testing.T) {
+	cases := []struct {
+		Input  string
+		Output string
+	}{
+		{
+			`{{template_path}}`,
+			`foo`,
+		},
+	}
+
+	ctx := &Context{
+		TemplatePath: "foo",
+	}
+	for _, tc := range cases {
+		i := &I{Value: tc.Input}
+		result, err := i.Render(ctx)
+		if err != nil {
+			t.Fatalf("Input: %s\n\nerr: %s", tc.Input, err)
+		}
+
+		if result != tc.Output {
+			t.Fatalf("Input: %s\n\nGot: %s", tc.Input, result)
+		}
+	}
+}
+
 func TestFuncTimestamp(t *testing.T) {
 	expected := strconv.FormatInt(InitTime.Unix(), 10)
 

template/interpolate/i.go

@@ -14,6 +14,10 @@ type Context struct {
 	// Funcs are extra functions available in the template
 	Funcs map[string]interface{}
 
+	// TemplatePath is the path to the template that this is being
+	// rendered within.
+	TemplatePath string
+
 	// UserVariables is the mapping of user variables that the
 	// "user" function reads from.
 	UserVariables map[string]string