IGNITE-26385 Add check that ignite-json is enabled when using ignite-rest-http module

docs/_docs/quick-start/restapi.adoc

@@ -29,7 +29,7 @@ include::includes/prereqs.adoc[]
 include::includes/install-ignite.adoc[]
 
 Once that's done, you will need to enable HTTP connectivity.
-To do this, copy the `ignite-rest-http` module from `{IGNITE_HOME}/libs/optional/` to the `{IGNITE_HOME}/libs` folder.
+To do this, copy the `ignite-rest-http` and `ignite-json` modules from `{IGNITE_HOME}/libs/optional/` to the `{IGNITE_HOME}/libs` folder.
 
 == Starting a Node
 

docs/_docs/restapi.adoc

@@ -22,8 +22,8 @@ Internally, Ignite uses Jetty to provide HTTP server features. See <<Configurati
 
 == Getting Started
 
-To enable HTTP connectivity, make sure that the `ignite-rest-http` module is enabled.
-If you use the binary distribution, copy the `ignite-rest-http` module from `IGNITE_HOME/libs/optional/` to the `IGNITE_HOME/libs` folder.
+To enable HTTP connectivity, make sure that the `ignite-rest-http` and `ignite-json` modules are enabled.
+If you use the binary distribution, copy the `ignite-rest-http` and `ignite-json` modules from `IGNITE_HOME/libs/optional/` to the `IGNITE_HOME/libs` folder.
 See link:setup#enabling-modules[Enabling modules] for details.
 
 Explicit configuration is not required; the connector starts up automatically and listens on port `8080`. You can check if it works with curl:

modules/rest-http/src/main/java/org/apache/ignite/internal/processors/rest/protocols/http/jetty/GridJettyRestProtocol.java

@@ -49,6 +49,7 @@
 import org.jetbrains.annotations.Nullable;
 import org.xml.sax.SAXException;
 
+import static org.apache.ignite.IgniteCommonsSystemProperties.IGNITE_HOME;
 import static org.apache.ignite.IgniteSystemProperties.IGNITE_JETTY_HOST;
 import static org.apache.ignite.IgniteSystemProperties.IGNITE_JETTY_LOG_NO_OVERRIDE;
 import static org.apache.ignite.IgniteSystemProperties.IGNITE_JETTY_PORT;
@@ -71,6 +72,9 @@ public class GridJettyRestProtocol extends GridRestProtocolAdapter {
         }
     }
 
+    /** Object mapper class name. */
+    private static final String IGNITE_OBJECT_MAPPER = "org.apache.ignite.internal.jackson.IgniteObjectMapper";
+
     /** Jetty handler. */
     private GridJettyRestHandler jettyHnd;
 
@@ -93,6 +97,11 @@ public GridJettyRestProtocol(GridKernalContext ctx) {
     @Override public void start(GridRestProtocolHandler hnd) throws IgniteCheckedException {
         assert ctx.config().getConnectorConfiguration() != null;
 
+        if (!checkJacksonEnabled())
+            throw new IgniteCheckedException("Can't find ignite-json module in classpath, which is required for REST API " +
+                "functionality. Copy ignite-json module from " + IGNITE_HOME + "/libs/optional/ to " + IGNITE_HOME +
+                "/libs folder.");
+
         String jettyHost = System.getProperty(IGNITE_JETTY_HOST, ctx.config().getLocalHost());
 
         try {
@@ -330,6 +339,20 @@ private AbstractNetworkConnector getJettyConnector() throws IgniteCheckedExcepti
                 httpSrv.getConnectors().length + "connectorsExpected=1]");
     }
 
+    /**
+     * Check if ignite-json module enabled.
+     */
+    private static boolean checkJacksonEnabled() {
+        try {
+            Class.forName(IGNITE_OBJECT_MAPPER);
+
+            return true;
+        }
+        catch (Exception e) {
+            return false;
+        }
+    }
+
     /**
      * Stops Jetty.
      */