From f5074cd521d777a5350731f1548b9cdcd90e7f43 Mon Sep 17 00:00:00 2001
From: Colin Hebert <hebert.colin@gmail.com>
Date: Sat, 30 Jan 2016 10:28:04 +1100
Subject: [PATCH] Add the trim() interpolation function

---
 config/interpolate_funcs.go                          | 12 ++++++++++++
 config/interpolate_funcs_test.go                     | 12 ++++++++++++
 .../source/docs/configuration/interpolation.html.md  |  2 ++
 3 files changed, 26 insertions(+)

diff --git a/config/interpolate_funcs.go b/config/interpolate_funcs.go
index a0ceeeec4..1757da79a 100644
--- a/config/interpolate_funcs.go
+++ b/config/interpolate_funcs.go
@@ -41,6 +41,7 @@ func Funcs() map[string]ast.Function {
 		"split":        interpolationFuncSplit(),
 		"sha1":         interpolationFuncSha1(),
 		"sha256":       interpolationFuncSha256(),
+		"strip":        interpolationFuncStrip(),
 		"base64encode": interpolationFuncBase64Encode(),
 		"base64decode": interpolationFuncBase64Decode(),
 		"upper":        interpolationFuncUpper(),
@@ -617,3 +618,14 @@ func interpolationFuncSha256() ast.Function {
 		},
 	}
 }
+
+func interpolationFuncTrim() ast.Function {
+	return ast.Function{
+		ArgTypes:   []ast.Type{ast.TypeString},
+		ReturnType: ast.TypeString,
+		Callback: func(args []interface{}) (interface{}, error) {
+			trim := args[0].(string)
+			return strings.TrimSpace(trim), nil
+		},
+	}
+}
diff --git a/config/interpolate_funcs_test.go b/config/interpolate_funcs_test.go
index 78139aa2d..b80d7456b 100644
--- a/config/interpolate_funcs_test.go
+++ b/config/interpolate_funcs_test.go
@@ -858,6 +858,18 @@ func TestInterpolateFuncSha256(t *testing.T) {
 	})
 }
 
+func TestInterpolateFuncTrim(t *testing.T) {
+	testFunction(t, testFunctionConfig{
+		Cases: []testFunctionCase{
+			{
+				`${trim(" test ")}`,
+				"test",
+				false,
+			},
+		},
+	})
+}
+
 type testFunctionConfig struct {
 	Cases []testFunctionCase
 	Vars  map[string]ast.Variable
diff --git a/website/source/docs/configuration/interpolation.html.md b/website/source/docs/configuration/interpolation.html.md
index 77c40e59e..e43f524b3 100644
--- a/website/source/docs/configuration/interpolation.html.md
+++ b/website/source/docs/configuration/interpolation.html.md
@@ -176,6 +176,8 @@ The supported built-in functions are:
       `a_resource_param = ["${split(",", var.CSV_STRING)}"]`.
       Example: `split(",", module.amod.server_ids)`
 
+  * `trim(string)` - Returns a copy of the string with all leading and trailing white spaces removed.
+
   * `upper(string)` - Returns a copy of the string with all Unicode letters mapped to their upper case.
 
 ## Templates