From a303817e03bc048c5656f4648e91fa3384c981f3 Mon Sep 17 00:00:00 2001
From: Gorka Lerchundi Osa <glertxundi@gmail.com>
Date: Wed, 11 Nov 2015 09:51:30 +0100
Subject: [PATCH] config: base64gzip interpolation function

Since Terraform's internals are not 8-bit clean (it assumes UTF-8
strings), we can't implement raw gzip directly. We're going to add
support where it makes sense for passing data to attributes as
base64 so that the result of this function can be used.
---
 config/interpolate_funcs.go                   | 29 +++++++++++++++++++
 config/interpolate_funcs_test.go              | 12 ++++++++
 .../docs/configuration/interpolation.html.md  |  5 ++++
 3 files changed, 46 insertions(+)

diff --git a/config/interpolate_funcs.go b/config/interpolate_funcs.go
index 2c5e660a6..0160bef05 100644
--- a/config/interpolate_funcs.go
+++ b/config/interpolate_funcs.go
@@ -1,6 +1,8 @@
 package config
 
 import (
+	"bytes"
+	"compress/gzip"
 	"crypto/md5"
 	"crypto/sha1"
 	"crypto/sha256"
@@ -58,6 +60,7 @@ func Funcs() map[string]ast.Function {
 		"basename":     interpolationFuncBasename(),
 		"base64decode": interpolationFuncBase64Decode(),
 		"base64encode": interpolationFuncBase64Encode(),
+		"base64gzip":   interpolationFuncBase64Gzip(),
 		"base64sha256": interpolationFuncBase64Sha256(),
 		"base64sha512": interpolationFuncBase64Sha512(),
 		"bcrypt":       interpolationFuncBcrypt(),
@@ -1205,6 +1208,32 @@ func interpolationFuncBase64Decode() ast.Function {
 	}
 }
 
+// interpolationFuncBase64Gzip implements the "gzip" function that allows gzip
+// compression encoding the result using base64
+func interpolationFuncBase64Gzip() ast.Function {
+	return ast.Function{
+		ArgTypes:   []ast.Type{ast.TypeString},
+		ReturnType: ast.TypeString,
+		Callback: func(args []interface{}) (interface{}, error) {
+			s := args[0].(string)
+
+			var b bytes.Buffer
+			gz := gzip.NewWriter(&b)
+			if _, err := gz.Write([]byte(s)); err != nil {
+				return "", fmt.Errorf("failed to write gzip raw data: '%s'", s)
+			}
+			if err := gz.Flush(); err != nil {
+				return "", fmt.Errorf("failed to flush gzip writer: '%s'", s)
+			}
+			if err := gz.Close(); err != nil {
+				return "", fmt.Errorf("failed to close gzip writer: '%s'", s)
+			}
+
+			return base64.StdEncoding.EncodeToString(b.Bytes()), nil
+		},
+	}
+}
+
 // interpolationFuncLower implements the "lower" function that does
 // string lower casing.
 func interpolationFuncLower() ast.Function {
diff --git a/config/interpolate_funcs_test.go b/config/interpolate_funcs_test.go
index 8ed0734a6..2719f3fca 100644
--- a/config/interpolate_funcs_test.go
+++ b/config/interpolate_funcs_test.go
@@ -2249,6 +2249,18 @@ func TestInterpolateFuncTrimSpace(t *testing.T) {
 	})
 }
 
+func TestInterpolateFuncBase64Gzip(t *testing.T) {
+	testFunction(t, testFunctionConfig{
+		Cases: []testFunctionCase{
+			{
+				`${base64gzip("test")}`,
+				"H4sIAAAAAAAA/ypJLS4BAAAA//8BAAD//wx+f9gEAAAA",
+				false,
+			},
+		},
+	})
+}
+
 func TestInterpolateFuncBase64Sha256(t *testing.T) {
 	testFunction(t, testFunctionConfig{
 		Cases: []testFunctionCase{
diff --git a/website/docs/configuration/interpolation.html.md b/website/docs/configuration/interpolation.html.md
index aea83516c..12700b2d8 100644
--- a/website/docs/configuration/interpolation.html.md
+++ b/website/docs/configuration/interpolation.html.md
@@ -153,6 +153,11 @@ The supported built-in functions are:
   * `base64encode(string)` - Returns a base64-encoded representation of the
     given string.
 
+  * `base64gzip(string)` - Compresses the given string with gzip and then
+    encodes the result to base64. This can be used with certain resource
+    arguments that allow binary data to be passed with base64 encoding, since
+    Terraform strings are required to be valid UTF-8.
+
   * `base64sha256(string)` - Returns a base64-encoded representation of raw
     SHA-256 sum of the given string.
     **This is not equivalent** of `base64encode(sha256(string))`