Ensure enrich policy is immutable (#43604)

This commit ensures the policy cannot be overwritten. An error is thrown
if the policy exists. All tests have been updated accordingly.

x-pack/plugin/enrich/qa/common/src/main/java/org/elasticsearch/test/enrich/CommonEnrichRestTestCase.java

@@ -8,6 +8,7 @@ package org.elasticsearch.test.enrich;
 import org.apache.http.util.EntityUtils;
 import org.elasticsearch.client.Request;
 import org.elasticsearch.client.Response;
+import org.elasticsearch.client.ResponseException;
 import org.elasticsearch.common.xcontent.XContentHelper;
 import org.elasticsearch.common.xcontent.json.JsonXContent;
 import org.elasticsearch.test.rest.ESRestTestCase;
@@ -76,6 +77,16 @@ public abstract class CommonEnrichRestTestCase extends ESRestTestCase {
         assertThat(_source.get("tld_rank"), equalTo(7));
     }
 
+    public void testImmutablePolicy() throws IOException {
+        Request putPolicyRequest = new Request("PUT", "/_enrich/policy/my_policy");
+        putPolicyRequest.setJsonEntity("{\"type\": \"exact_match\",\"indices\": [\"my-source-index\"], \"enrich_key\": \"host\", " +
+            "\"enrich_values\": [\"globalRank\", \"tldRank\", \"tld\"]}");
+        assertOK(client().performRequest(putPolicyRequest));
+
+        ResponseException exc = expectThrows(ResponseException.class, () -> client().performRequest(putPolicyRequest));
+        assertTrue(exc.getMessage().contains("policy [my_policy] already exists"));
+    }
+
     private static Map<String, Object> toMap(Response response) throws IOException {
         return toMap(EntityUtils.toString(response.getEntity()));
     }

x-pack/plugin/enrich/src/main/java/org/elasticsearch/xpack/enrich/EnrichStore.java

@@ -5,6 +5,7 @@
  */
 package org.elasticsearch.xpack.enrich;
 
+import org.elasticsearch.ResourceAlreadyExistsException;
 import org.elasticsearch.ResourceNotFoundException;
 import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.cluster.ClusterStateUpdateTask;
@@ -46,6 +47,9 @@ public final class EnrichStore {
 
         updateClusterState(clusterService, handler, current -> {
             final Map<String, EnrichPolicy> policies = getPolicies(current);
+            if (policies.get(name) != null) {
+                throw new ResourceAlreadyExistsException("policy [{}] already exists", name);
+            }
             policies.put(name, policy);
             return policies;
         });

x-pack/plugin/enrich/src/test/java/org/elasticsearch/xpack/enrich/EnrichPolicyUpdateTests.java

@@ -5,6 +5,7 @@
  */
 package org.elasticsearch.xpack.enrich;
 
+import org.elasticsearch.ResourceAlreadyExistsException;
 import org.elasticsearch.action.ingest.PutPipelineRequest;
 import org.elasticsearch.common.bytes.BytesArray;
 import org.elasticsearch.common.xcontent.XContentType;
@@ -21,7 +22,6 @@ import java.util.Collections;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.instanceOf;
-import static org.hamcrest.Matchers.sameInstance;
 
 public class EnrichPolicyUpdateTests extends ESSingleNodeTestCase {
 
@@ -49,11 +49,8 @@ public class EnrichPolicyUpdateTests extends ESSingleNodeTestCase {
 
         EnrichPolicy instance2 = new EnrichPolicy(EnrichPolicy.EXACT_MATCH_TYPE, null, Collections.singletonList("index"),
             "key2", Collections.singletonList("field2"));
-        putPolicyRequest = new PutEnrichPolicyAction.Request("my_policy", instance2);
+        ResourceAlreadyExistsException exc = expectThrows(ResourceAlreadyExistsException.class, () ->
-        assertAcked(client().execute(PutEnrichPolicyAction.INSTANCE, putPolicyRequest).actionGet());
+            client().execute(PutEnrichPolicyAction.INSTANCE, new PutEnrichPolicyAction.Request("my_policy", instance2)).actionGet());
-        assertThat(enrichProcessorFactory.policies.get("my_policy"), equalTo(instance2));
+        assertTrue(exc.getMessage().contains("policy [my_policy] already exists"));
-
-        Pipeline pipelineInstance2 = ingestService.getPipeline("1");
-        assertThat(pipelineInstance2, sameInstance(pipelineInstance1));
     }
 }

x-pack/plugin/enrich/src/test/java/org/elasticsearch/xpack/enrich/EnrichStoreTests.java

@@ -41,6 +41,22 @@ public class EnrichStoreTests extends ESSingleNodeTestCase {
         assertThat(result, nullValue());
     }
 
+    public void testImmutability() throws Exception {
+        EnrichPolicy policy = randomEnrichPolicy(XContentType.JSON);
+        ClusterService clusterService = getInstanceFromNode(ClusterService.class);
+        String name = "my-policy";
+
+        AtomicReference<Exception> error = saveEnrichPolicy(name, policy, clusterService);
+        assertThat(error.get(), nullValue());
+
+        error = saveEnrichPolicy(name, policy, clusterService);
+        assertTrue(error.get().getMessage().contains("policy [my-policy] already exists"));;
+
+        deleteEnrichPolicy(name, clusterService);
+        EnrichPolicy result = EnrichStore.getPolicy(name, clusterService.state());
+        assertThat(result, nullValue());
+    }
+
     public void testPutValidation() throws Exception {
         EnrichPolicy policy = randomEnrichPolicy(XContentType.JSON);
         ClusterService clusterService = getInstanceFromNode(ClusterService.class);