add gzipbase64 interpolation function

config/interpolate_funcs.go

@@ -1,6 +1,8 @@
 package config
 
 import (
+	"bytes"
+	"compress/gzip"
 	"crypto/md5"
 	"crypto/sha1"
 	"crypto/sha256"
@@ -72,6 +74,7 @@ func Funcs() map[string]ast.Function {
 		"distinct":     interpolationFuncDistinct(),
 		"element":      interpolationFuncElement(),
 		"file":         interpolationFuncFile(),
+		"gzipbase64":   interpolationFuncGzipBase64(),
 		"matchkeys":    interpolationFuncMatchKeys(),
 		"floor":        interpolationFuncFloor(),
 		"format":       interpolationFuncFormat(),
@@ -1322,6 +1325,28 @@ func interpolationFuncBase64Sha512() ast.Function {
 	}
 }
 
+func interpolationFuncGzipBase64() 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 gzip raw data: '%s'", s)
+			}
+			if err := gz.Flush(); err != nil {
+				return "", fmt.Errorf("failed to gzip raw data: '%s'", s)
+			}
+			if err := gz.Close(); err != nil {
+				return "", fmt.Errorf("failed to gzip raw data: '%s'", s)
+			}
+			return base64.StdEncoding.EncodeToString(b.Bytes()), nil
+		},
+	}
+}
+
 func interpolationFuncUUID() ast.Function {
 	return ast.Function{
 		ArgTypes:   []ast.Type{},

config/interpolate_funcs_test.go

@@ -2249,6 +2249,18 @@ func TestInterpolateFuncBase64Sha512(t *testing.T) {
 	})
 }
 
+func TestInterpolateFuncGzip(t *testing.T) {
+	testFunction(t, testFunctionConfig{
+		Cases: []testFunctionCase{
+			{
+				`${gzipbase64("test")}`,
+				"H4sIAAAAAAAA/ypJLS4BAAAA//8BAAD//wx+f9gEAAAA",
+				false,
+			},
+		},
+	})
+}
+
 func TestInterpolateFuncMd5(t *testing.T) {
 	testFunction(t, testFunctionConfig{
 		Cases: []testFunctionCase{