throw exception when grok processor does not match

plugins/ingest/src/main/java/org/elasticsearch/ingest/processor/grok/GrokProcessor.java

@@ -44,14 +44,13 @@ public final class GrokProcessor implements Processor {
     }
 
     @Override
-    public void execute(IngestDocument ingestDocument) {
-        Object field = ingestDocument.getFieldValue(matchField, Object.class);
-        // TODO(talevy): handle invalid field types
-        if (field instanceof String) {
-            Map<String, Object> matches = grok.captures((String) field);
-            if (matches != null) {
-                matches.forEach((k, v) -> ingestDocument.setFieldValue(k, v));
-            }
+    public void execute(IngestDocument ingestDocument) throws Exception {
+        String fieldValue = ingestDocument.getFieldValue(matchField, String.class);
+        Map<String, Object> matches = grok.captures(fieldValue);
+        if (matches != null) {
+            matches.forEach((k, v) -> ingestDocument.setFieldValue(k, v));
+        } else {
+            throw new IllegalArgumentException("Grok expression does not match field value: [" + fieldValue + "]");
         }
     }
 

plugins/ingest/src/test/java/org/elasticsearch/ingest/processor/grok/GrokProcessorTests.java

@@ -0,0 +1,83 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.ingest.processor.grok;
+
+import org.elasticsearch.ingest.IngestDocument;
+import org.elasticsearch.ingest.RandomDocumentPicks;
+import org.elasticsearch.test.ESTestCase;
+
+import java.util.*;
+
+import static org.hamcrest.Matchers.*;
+
+
+public class GrokProcessorTests extends ESTestCase {
+
+    public void testMatch() throws Exception {
+        String fieldName = RandomDocumentPicks.randomFieldName(random());
+        IngestDocument doc = new IngestDocument("index", "type", "id", new HashMap<>());
+        doc.setFieldValue(fieldName, "1");
+        Grok grok = new Grok(Collections.singletonMap("ONE", "1"), "%{ONE:one}");
+        GrokProcessor processor = new GrokProcessor(grok, fieldName);
+        processor.execute(doc);
+        assertThat(doc.getFieldValue("one", String.class), equalTo("1"));
+    }
+
+    public void testNoMatch() {
+        String fieldName = RandomDocumentPicks.randomFieldName(random());
+        IngestDocument doc = new IngestDocument("index", "type", "id", new HashMap<>());
+        doc.setFieldValue(fieldName, "23");
+        Grok grok = new Grok(Collections.singletonMap("ONE", "1"), "%{ONE:one}");
+        GrokProcessor processor = new GrokProcessor(grok, fieldName);
+        try {
+            processor.execute(doc);
+            fail();
+        } catch (Exception e) {
+            assertThat(e.getMessage(), equalTo("Grok expression does not match field value: [23]"));
+        }
+    }
+
+    public void testNotStringField() {
+        String fieldName = RandomDocumentPicks.randomFieldName(random());
+        IngestDocument doc = new IngestDocument("index", "type", "id", new HashMap<>());
+        doc.setFieldValue(fieldName, 1);
+        Grok grok = new Grok(Collections.singletonMap("ONE", "1"), "%{ONE:one}");
+        GrokProcessor processor = new GrokProcessor(grok, fieldName);
+        try {
+            processor.execute(doc);
+            fail();
+        } catch (Exception e) {
+            assertThat(e.getMessage(), equalTo("field [" + fieldName + "] of type [java.lang.Integer] cannot be cast to [java.lang.String]"));
+        }
+    }
+
+    public void testMissingField() {
+        String fieldName = "foo.bar";
+        IngestDocument doc = new IngestDocument("index", "type", "id", new HashMap<>());
+        Grok grok = new Grok(Collections.singletonMap("ONE", "1"), "%{ONE:one}");
+        GrokProcessor processor = new GrokProcessor(grok, fieldName);
+        try {
+            processor.execute(doc);
+            fail();
+        } catch (Exception e) {
+            assertThat(e.getMessage(), equalTo("field [foo] not present as part of path [foo.bar]"));
+        }
+    }
+}

plugins/ingest/src/test/java/org/elasticsearch/ingest/processor/grok/GrokTests.java

@@ -281,4 +281,11 @@ public class GrokTests extends ESTestCase {
 
         assertEquals(expected, actual);
     }
+
+    public void testNoMatch() {
+        Map<String, String> bank = new HashMap<>();
+        bank.put("MONTHDAY", "(?:(?:0[1-9])|(?:[12][0-9])|(?:3[01])|[1-9])");
+        Grok grok = new Grok(bank, "%{MONTHDAY:greatday}");
+        assertThat(grok.captures("nomatch"), nullValue());
+    }
 }