Rename and document field in index resolution (#136694)

Author: idegtiarenko

server/src/main/java/org/elasticsearch/action/ResolvedIndexExpression.java

@@ -32,7 +32,7 @@
  * {
  *   "original": "my-index-*",
  *   "localExpressions": {
- *     "expressions": ["my-index-000001", "my-index-000002"],
+ *     "indices": ["my-index-000001", "my-index-000002"],
  *     "localIndexResolutionResult": "SUCCESS"
  *   },
  *   "remoteExpressions": ["remote1:my-index-*", "remote2:my-index-*"]
@@ -42,7 +42,8 @@
  * @param original the original index expression, as provided by the user
  * @param localExpressions the local expressions that replace the original along with their resolution result
  *                         and failure info
- * @param remoteExpressions the remote expressions that replace the original
+ * @param remoteExpressions the remote expressions that replace the original one (in the case of CPS/flat index resolution).
+ *                          Only set on the local ResolvedIndexExpression, empty otherwise.
  */
 public record ResolvedIndexExpression(String original, LocalExpressions localExpressions, Set<String> remoteExpressions)
     implements
@@ -64,7 +65,7 @@ public void writeTo(StreamOutput out) throws IOException {
      * Failures can be due to concrete resources not being visible (either missing or not visible due to indices options)
      * or unauthorized concrete resources.
      * A wildcard expression resolving to nothing is still considered a successful resolution.
-     * The NONE result indicates that no local resolution was attempted, because the expression is known to be remote-only.
+     * The NONE result indicates that no local resolution was attempted because the expression is known to be remote-only.
      */
     public enum LocalIndexResolutionResult {
         NONE,
@@ -75,9 +76,11 @@ public enum LocalIndexResolutionResult {
 
     /**
      * Represents local (non-remote) resolution results, including expanded indices, and a {@link LocalIndexResolutionResult}.
+     *
+     * @param indices represents the resolved concrete indices backing the expression
      */
     public record LocalExpressions(
-        Set<String> expressions,
+        Set<String> indices,
         LocalIndexResolutionResult localIndexResolutionResult,
         @Nullable ElasticsearchException exception
     ) implements Writeable {
@@ -99,7 +102,7 @@ public LocalExpressions(StreamInput in) throws IOException {
 
         @Override
         public void writeTo(StreamOutput out) throws IOException {
-            out.writeStringCollection(expressions);
+            out.writeStringCollection(indices);
             out.writeEnum(localIndexResolutionResult);
             ElasticsearchException.writeException(exception, out);
         }

server/src/main/java/org/elasticsearch/action/ResolvedIndexExpressions.java

@@ -33,7 +33,7 @@ public ResolvedIndexExpressions(StreamInput in) throws IOException {
     }
 
     public List<String> getLocalIndicesList() {
-        return expressions.stream().flatMap(e -> e.localExpressions().expressions().stream()).toList();
+        return expressions.stream().flatMap(e -> e.localExpressions().indices().stream()).toList();
     }
 
     public List<String> getRemoteIndicesList() {
@@ -86,7 +86,7 @@ public void excludeFromLocalExpressions(Set<String> expressionsToExclude) {
             Objects.requireNonNull(expressionsToExclude);
             if (expressionsToExclude.isEmpty() == false) {
                 for (ResolvedIndexExpression prior : expressions) {
-                    final Set<String> localExpressions = prior.localExpressions().expressions();
+                    final Set<String> localExpressions = prior.localExpressions().indices();
                     if (localExpressions.isEmpty()) {
                         continue;
                     }

server/src/main/java/org/elasticsearch/search/crossproject/CrossProjectIndexResolutionValidator.java

@@ -98,12 +98,7 @@ public static ElasticsearchException validate(
             ResolvedIndexExpression.LocalExpressions localExpressions = localResolvedIndices.localExpressions();
             ResolvedIndexExpression.LocalIndexResolutionResult result = localExpressions.localIndexResolutionResult();
             if (isQualifiedExpression) {
-                ElasticsearchException e = checkResolutionFailure(
-                    localExpressions.expressions(),
-                    result,
-                    originalExpression,
-                    indicesOptions
-                );
+                ElasticsearchException e = checkResolutionFailure(localExpressions.indices(), result, originalExpression, indicesOptions);
                 if (e != null) {
                     return e;
                 }
@@ -123,7 +118,7 @@ public static ElasticsearchException validate(
                 }
             } else {
                 ElasticsearchException localException = checkResolutionFailure(
-                    localExpressions.expressions(),
+                    localExpressions.indices(),
                     result,
                     originalExpression,
                     indicesOptions
@@ -196,7 +191,7 @@ private static ElasticsearchException checkSingleRemoteExpression(
         }
 
         return checkResolutionFailure(
-            matchingExpression.expressions(),
+            matchingExpression.indices(),
             matchingExpression.localIndexResolutionResult(),
             remoteExpression,
             indicesOptions

x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authz/IndicesAndAliasesResolverTests.java

@@ -2000,7 +2000,7 @@ public void testXPackSecurityUserHasAccessToSecurityIndex() {
             assertEquals(1, resolved.expressions().size());
             var expression = resolved.expressions().getFirst();
             assertEquals("_all", expression.original());
-            assertThat(expression.localExpressions().expressions(), hasItem(SECURITY_MAIN_ALIAS));
+            assertThat(expression.localExpressions().indices(), hasItem(SECURITY_MAIN_ALIAS));
         }
         {
             IndicesAliasesRequest aliasesRequest = new IndicesAliasesRequest(TEST_REQUEST_TIMEOUT, TEST_REQUEST_TIMEOUT);
@@ -2025,7 +2025,7 @@ public void testXPackUserDoesNotHaveAccessToSecurityIndex() {
         assertEquals(1, resolved.expressions().size());
         var expression = resolved.expressions().getFirst();
         assertEquals("_all", expression.original());
-        assertThat(expression.localExpressions().expressions(), not(hasItem(SECURITY_MAIN_ALIAS)));
+        assertThat(expression.localExpressions().indices(), not(hasItem(SECURITY_MAIN_ALIAS)));
     }
 
     public void testNonXPackUserAccessingSecurityIndex() {
@@ -2051,7 +2051,7 @@ public void testNonXPackUserAccessingSecurityIndex() {
             assertEquals(1, resolved.expressions().size());
             var expression = resolved.expressions().getFirst();
             assertEquals("_all", expression.original());
-            assertThat(expression.localExpressions().expressions(), not(hasItem(SECURITY_MAIN_ALIAS)));
+            assertThat(expression.localExpressions().indices(), not(hasItem(SECURITY_MAIN_ALIAS)));
         }
 
         {