switch to graal JS engine (#461)

Nashorn has been removed in jdk15. Move to Graal to make
it compile and run on newer JDKs.

build.sbt

@@ -47,6 +47,8 @@ lazy val `iep-config` = project
   .settings(libraryDependencies ++= Seq(
     Dependencies.archaiusBridge,
     Dependencies.archaiusCore,
+    Dependencies.graalJs,
+    Dependencies.graalJsEngine,
     Dependencies.guiceCore,
     Dependencies.jodaTime,
     Dependencies.equalsVerifier % "test"

iep-config/src/main/java/com/netflix/iep/config/ConfigFile.java

@@ -15,6 +15,9 @@
  */
 package com.netflix.iep.config;
 
+import org.graalvm.polyglot.Context;
+import org.graalvm.polyglot.Value;
+
 import java.io.File;
 import java.io.IOException;
 import java.io.Reader;
@@ -30,10 +33,6 @@
 import java.util.Set;
 import java.util.TreeSet;
 import java.util.Comparator;
-import javax.script.ScriptEngineManager;
-import javax.script.ScriptEngine;
-import javax.script.SimpleBindings;
-import javax.script.ScriptException;
 
 /**
  * Helpers for loading configuration properties with scoped blocks.
@@ -55,21 +54,12 @@
 public class ConfigFile {
 
   public static boolean checkScope(Map<String,String> vars, String str) {
-    ScriptEngineManager mgr = new ScriptEngineManager(null);
-    ScriptEngine engine = mgr.getEngineByName("javascript");
-
-    if (engine == null) throw new IllegalStateException("no javascipt engine found");
-
-    SimpleBindings bindings = new SimpleBindings();
+    Context context = Context.create();
+    Value bindings = context.getBindings("js");
     for (Map.Entry<String,String> t : vars.entrySet()) {
-      bindings.put(t.getKey(), t.getValue());
-    }
-    try {
-      return (Boolean) engine.eval(str, bindings);
-    }
-    catch (ScriptException e) {
-      throw new RuntimeException(e);
+      bindings.putMember(t.getKey(), t.getValue());
     }
+    return context.eval("js", str).asBoolean();
   }
 
   /** Load the configuration file using the system environment variables as the `vars`. */

project/Dependencies.scala

@@ -7,6 +7,7 @@ object Dependencies {
     val aws        = "1.11.847"
     val aws2       = "2.14.4"
     val eureka     = "1.9.25"
+    val graal      = "20.0.0"
     val guice      = "4.1.0"
     val jackson    = "2.11.2"
     val rxnetty    = "0.4.20"
@@ -47,6 +48,8 @@ object Dependencies {
   val caffeine           = "com.github.ben-manes.caffeine" % "caffeine" % "2.8.5"
   val equalsVerifier     = "nl.jqno.equalsverifier" % "equalsverifier" % "3.4.2"
   val eurekaClient       = "com.netflix.eureka" % "eureka-client" % eureka
+  val graalJs            = "org.graalvm.js" % "js" % graal
+  val graalJsEngine      = "org.graalvm.js" % "js-scriptengine" % graal
   val guiceCore          = "com.google.inject" % "guice" % guice
   val guiceMulti         = "com.google.inject.extensions" % "guice-multibindings" % guice
   val inject             = "javax.inject" % "javax.inject" % "1"