add hot reload functionnality for mock server

karate-core/src/main/java/com/intuit/karate/netty/FileChangedWatcher.java

@@ -0,0 +1,61 @@
+package com.intuit.karate.netty;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.FileSystems;
+import java.nio.file.Path;
+import java.nio.file.StandardWatchEventKinds;
+import java.nio.file.WatchEvent;
+import java.nio.file.WatchKey;
+import java.nio.file.WatchService;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class FileChangedWatcher {
+
+  private static final Logger logger = LoggerFactory.getLogger(FileChangedWatcher.class);
+
+  private File file;
+  private FeatureServer server;
+  private Integer port;
+  private boolean ssl;
+  private File cert;
+  private File key;
+
+  public FileChangedWatcher(File mock, FeatureServer server, Integer port, boolean ssl, File cert, File key) {
+    this.file = mock;
+    this.server = server;
+    this.port = port;
+    this.ssl = ssl;
+    this.cert = cert;
+    this.key = key;
+  }
+
+  public void watch() throws InterruptedException, IOException {
+
+    try {
+      final Path directoryPath = file.toPath().getParent();
+      final WatchService watchService = FileSystems.getDefault().newWatchService();
+      directoryPath.register(watchService, StandardWatchEventKinds.ENTRY_MODIFY);
+      while (true) {
+        final WatchKey wk = watchService.take();
+        for (WatchEvent<?> event : wk.pollEvents()) {
+          final Path fileChangedPath = (Path) event.context();
+          if (fileChangedPath.endsWith(file.getName())) {
+            onModified();
+          }
+        }
+        wk.reset();
+      }
+    } catch (Exception exception) {
+      logger.error("exception when handling change of mock file");
+    }
+  }
+
+  public void onModified() {
+    if (server != null) {
+      server.stop();
+      server = FeatureServer.start(file, port, ssl, cert, key, null);
+    }
+  }
+}

karate-netty/src/main/java/com/intuit/karate/Main.java

@@ -28,6 +28,7 @@
 import com.intuit.karate.exception.KarateException;
 import com.intuit.karate.job.JobExecutor;
 import com.intuit.karate.netty.FeatureServer;
+import com.intuit.karate.netty.FileChangedWatcher;
 import java.io.File;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -199,8 +200,12 @@ public Void call() throws Exception {
             key = new File(FeatureServer.DEFAULT_KEY_NAME);
         }
         FeatureServer server = FeatureServer.start(mock, port, ssl, cert, key, null);
+
+        // hot reload
+        FileChangedWatcher watcher = new FileChangedWatcher(mock, server, port, ssl, cert, key);
+        watcher.watch();
+
         server.waitSync();
         return null;
     }
-
 }