provisioning: escape literal '$' with '$$' to avoid interpolation (#18045)

fixes #17986

pkg/services/provisioning/values/values_test.go

@@ -1,16 +1,18 @@
 package values
 
 import (
-	. "github.com/smartystreets/goconvey/convey"
-	"gopkg.in/yaml.v2"
 	"os"
 	"testing"
+
+	. "github.com/smartystreets/goconvey/convey"
+	"gopkg.in/yaml.v2"
 )
 
 func TestValues(t *testing.T) {
 	Convey("Values", t, func() {
 		os.Setenv("INT", "1")
 		os.Setenv("STRING", "test")
+		os.Setenv("EMPTYSTRING", "")
 		os.Setenv("BOOL", "true")
 
 		Convey("IntValue", func() {
@@ -61,6 +63,24 @@ func TestValues(t *testing.T) {
 				So(d.Val.Value(), ShouldEqual, "")
 				So(d.Val.Raw, ShouldEqual, "")
 			})
+
+			Convey("empty var should have empty value", func() {
+				unmarshalingTest(`val: $EMPTYSTRING`, d)
+				So(d.Val.Value(), ShouldEqual, "")
+				So(d.Val.Raw, ShouldEqual, "$EMPTYSTRING")
+			})
+
+			Convey("$$ should be a literal $", func() {
+				unmarshalingTest(`val: $$`, d)
+				So(d.Val.Value(), ShouldEqual, "$")
+				So(d.Val.Raw, ShouldEqual, "$$")
+			})
+
+			Convey("$$ should be a literal $ and not expanded within a string", func() {
+				unmarshalingTest(`val: mY,Passwo$$rd`, d)
+				So(d.Val.Value(), ShouldEqual, "mY,Passwo$rd")
+				So(d.Val.Raw, ShouldEqual, "mY,Passwo$$rd")
+			})
 		})
 
 		Convey("BoolValue", func() {
@@ -199,6 +219,7 @@ func TestValues(t *testing.T) {
 		Reset(func() {
 			os.Unsetenv("INT")
 			os.Unsetenv("STRING")
+			os.Unsetenv("EMPTYSTRING")
 			os.Unsetenv("BOOL")
 		})
 	})