From aa9f9486a8dd00b59fdc91a9f7ccfc762683ac5e Mon Sep 17 00:00:00 2001
From: nitrocode <nitrocode@users.noreply.github.com>
Date: Wed, 12 May 2021 11:27:21 -0400
Subject: [PATCH] Add templatestring function

---
 lang/funcs/filesystem.go      | 16 +++++++++++-----
 lang/funcs/filesystem_test.go |  2 +-
 lang/functions.go             |  7 ++++++-
 lang/functions_test.go        |  7 +++++++
 4 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/lang/funcs/filesystem.go b/lang/funcs/filesystem.go
index 1f00b50868fe..3efa82f83e4a 100644
--- a/lang/funcs/filesystem.go
+++ b/lang/funcs/filesystem.go
@@ -63,7 +63,7 @@ func MakeFileFunc(baseDir string, encBase64 bool) function.Function {
 // As a special exception, a referenced template file may not recursively call
 // the templatefile function, since that would risk the same file being
 // included into itself indefinitely.
-func MakeTemplateFileFunc(baseDir string, funcsCb func() map[string]function.Function) function.Function {
+func MakeTemplateFileFunc(baseDir string, templateFile bool, funcsCb func() map[string]function.Function) function.Function {
 
 	params := []function.Parameter{
 		{
@@ -79,9 +79,15 @@ func MakeTemplateFileFunc(baseDir string, funcsCb func() map[string]function.Fun
 	loadTmpl := func(fn string) (hcl.Expression, error) {
 		// We re-use File here to ensure the same filename interpretation
 		// as it does, along with its other safety checks.
-		tmplVal, err := File(baseDir, cty.StringVal(fn))
-		if err != nil {
-			return nil, err
+		var tmplVal cty.Value
+		if templateFile {
+			var err error
+			tmplVal, err = File(baseDir, cty.StringVal(fn))
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			tmplVal = cty.StringVal(fn)
 		}
 
 		expr, diags := hclsyntax.ParseTemplate([]byte(tmplVal.AsString()), fn, hcl.Pos{Line: 1, Column: 1})
@@ -128,7 +134,7 @@ func MakeTemplateFileFunc(baseDir string, funcsCb func() map[string]function.Fun
 		givenFuncs := funcsCb() // this callback indirection is to avoid chicken/egg problems
 		funcs := make(map[string]function.Function, len(givenFuncs))
 		for name, fn := range givenFuncs {
-			if name == "templatefile" {
+			if name == "templatefile" || name == "templatestring" {
 				// We stub this one out to prevent recursive calls.
 				funcs[name] = function.New(&function.Spec{
 					Params: params,
diff --git a/lang/funcs/filesystem_test.go b/lang/funcs/filesystem_test.go
index b91b52b1ed1a..8ffac0c63130 100644
--- a/lang/funcs/filesystem_test.go
+++ b/lang/funcs/filesystem_test.go
@@ -157,7 +157,7 @@ func TestTemplateFile(t *testing.T) {
 		},
 	}
 
-	templateFileFn := MakeTemplateFileFunc(".", func() map[string]function.Function {
+	templateFileFn := MakeTemplateFileFunc(".", true, func() map[string]function.Function {
 		return map[string]function.Function{
 			"join":         stdlib.JoinFunc,
 			"templatefile": MakeFileFunc(".", false), // just a placeholder, since templatefile itself overrides this
diff --git a/lang/functions.go b/lang/functions.go
index 21be9a7f1013..d5a918a8ccfc 100644
--- a/lang/functions.go
+++ b/lang/functions.go
@@ -146,11 +146,16 @@ func (s *Scope) Functions() map[string]function.Function {
 			"zipmap":           stdlib.ZipmapFunc,
 		}
 
-		s.funcs["templatefile"] = funcs.MakeTemplateFileFunc(s.BaseDir, func() map[string]function.Function {
+		s.funcs["templatefile"] = funcs.MakeTemplateFileFunc(s.BaseDir, true, func() map[string]function.Function {
 			// The templatefile function prevents recursive calls to itself
 			// by copying this map and overwriting the "templatefile" entry.
 			return s.funcs
 		})
+		s.funcs["templatestring"] = funcs.MakeTemplateFileFunc(s.BaseDir, false, func() map[string]function.Function {
+			// The templatestring function prevents recursive calls to itself
+			// by copying this map and overwriting the "templatestring" entry.
+			return s.funcs
+		})
 
 		if s.ConsoleMode {
 			// The type function is only available in terraform console.
diff --git a/lang/functions_test.go b/lang/functions_test.go
index c33bc3672a10..b504459b365d 100644
--- a/lang/functions_test.go
+++ b/lang/functions_test.go
@@ -869,6 +869,13 @@ func TestFunctions(t *testing.T) {
 			},
 		},
 
+		"templatestring": {
+			{
+				`templatestring("Hello, $${name}!", {name = "Jodie"})`,
+				cty.StringVal("Hello, Jodie!"),
+			},
+		},
+
 		"timeadd": {
 			{
 				`timeadd("2017-11-22T00:00:00Z", "1s")`,