Log when Data Prepper is shutdown via the HTTP shutdown endpoint. (#4001

)

Signed-off-by: David Venable <dlv@amazon.com>

data-prepper-core/src/main/java/org/opensearch/dataprepper/pipeline/server/ShutdownHandler.java

@@ -5,20 +5,20 @@
 
 package org.opensearch.dataprepper.pipeline.server;
 
-import org.opensearch.dataprepper.DataPrepper;
-import javax.ws.rs.HttpMethod;
-import java.io.IOException;
-import java.net.HttpURLConnection;
 import com.sun.net.httpserver.HttpExchange;
 import com.sun.net.httpserver.HttpHandler;
+import org.opensearch.dataprepper.DataPrepper;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import javax.ws.rs.HttpMethod;
+import java.io.IOException;
+import java.net.HttpURLConnection;
+
 /**
  * HttpHandler to handle requests to shut down the data prepper instance
  */
 public class ShutdownHandler implements HttpHandler {
-
     private final DataPrepper dataPrepper;
     private static final Logger LOG = LoggerFactory.getLogger(ShutdownHandler.class);
 
@@ -27,18 +27,19 @@ public ShutdownHandler(final DataPrepper dataPrepper) {
     }
 
     @Override
-    public void handle(HttpExchange exchange) throws IOException {
-        String requestMethod = exchange.getRequestMethod();
+    public void handle(final HttpExchange exchange) throws IOException {
+        final String requestMethod = exchange.getRequestMethod();
         if (!requestMethod.equals(HttpMethod.POST)) {
             exchange.sendResponseHeaders(HttpURLConnection.HTTP_BAD_METHOD, 0);
             exchange.getResponseBody().close();
             return;
         }
 
         try {
+            LOG.info("Received HTTP shutdown request to shutdown Data Prepper. Shutdown pipelines and server.");
             dataPrepper.shutdownPipelines();
             exchange.sendResponseHeaders(HttpURLConnection.HTTP_OK, 0);
-        } catch (Exception e) {
+        } catch (final Exception e) {
             LOG.error("Caught exception shutting down data prepper", e);
             exchange.sendResponseHeaders(HttpURLConnection.HTTP_INTERNAL_ERROR, 0);
         } finally {