CORE: Make Pattern Exclusion Work with Aliases (#33518)

* CORE: Make Pattern Exclusion Work with Aliases

* Adds the pattern exclusion logic to finding aliases
* Closes #33395

Author: original-brownbear

server/src/main/java/org/elasticsearch/cluster/metadata/MetaData.java

@@ -296,14 +296,38 @@ private ImmutableOpenMap<String, List<AliasMetaData>> findAliases(String[] origi
             return ImmutableOpenMap.of();
         }
 
-        boolean matchAllAliases = matchAllAliases(aliases);
+        String[] patterns = new String[aliases.length];
+        boolean[] include = new boolean[aliases.length];
+        for (int i = 0; i < aliases.length; i++) {
+            String alias = aliases[i];
+            if (alias.charAt(0) == '-') {
+                patterns[i] = alias.substring(1);
+                include[i] = false;
+            } else {
+                patterns[i] = alias;
+                include[i] = true;
+            }
+        }
+        boolean matchAllAliases = patterns.length == 0;
         ImmutableOpenMap.Builder<String, List<AliasMetaData>> mapBuilder = ImmutableOpenMap.builder();
         for (String index : concreteIndices) {
             IndexMetaData indexMetaData = indices.get(index);
             List<AliasMetaData> filteredValues = new ArrayList<>();
             for (ObjectCursor<AliasMetaData> cursor : indexMetaData.getAliases().values()) {
                 AliasMetaData value = cursor.value;
-                if (matchAllAliases || Regex.simpleMatch(aliases, value.alias())) {
+                boolean matched = matchAllAliases;
+                String alias = value.alias();
+                for (int i = 0; i < patterns.length; i++) {
+                    if (include[i]) {
+                        if (matched == false) {
+                            String pattern = patterns[i];
+                            matched = ALL.equals(pattern) || Regex.simpleMatch(pattern, alias);
+                        }
+                    } else if (matched) {
+                        matched = Regex.simpleMatch(patterns[i], alias) == false;
+                    }
+                }
+                if (matched) {
                     filteredValues.add(value);
                 }
             }
@@ -317,15 +341,6 @@ private ImmutableOpenMap<String, List<AliasMetaData>> findAliases(String[] origi
         return mapBuilder.build();
     }
 
-    private static boolean matchAllAliases(final String[] aliases) {
-        for (String alias : aliases) {
-            if (alias.equals(ALL)) {
-                return true;
-            }
-        }
-        return aliases.length == 0;
-    }
-
     /**
      * Checks if at least one of the specified aliases exists in the specified concrete indices. Wildcards are supported in the
      * alias names for partial matches.

server/src/test/java/org/elasticsearch/cluster/metadata/MetaDataTests.java

@@ -109,6 +109,38 @@ public void testFindAliases() {
         }
     }
 
+    public void testFindAliasWithExclusion() {
+        MetaData metaData = MetaData.builder().put(
+            IndexMetaData.builder("index")
+                .settings(Settings.builder().put(IndexMetaData.SETTING_VERSION_CREATED, Version.CURRENT))
+                .numberOfShards(1)
+                .numberOfReplicas(0)
+                .putAlias(AliasMetaData.builder("alias1").build())
+                .putAlias(AliasMetaData.builder("alias2").build())
+        ).build();
+        List<AliasMetaData> aliases =
+            metaData.findAliases(new GetAliasesRequest().aliases("*", "-alias1"), new String[] {"index"}).get("index");
+        assertThat(aliases.size(), equalTo(1));
+        assertThat(aliases.get(0).alias(), equalTo("alias2"));
+    }
+
+    public void testFindAliasWithExclusionAndOverride() {
+        MetaData metaData = MetaData.builder().put(
+            IndexMetaData.builder("index")
+                .settings(Settings.builder().put(IndexMetaData.SETTING_VERSION_CREATED, Version.CURRENT))
+                .numberOfShards(1)
+                .numberOfReplicas(0)
+                .putAlias(AliasMetaData.builder("aa").build())
+                .putAlias(AliasMetaData.builder("ab").build())
+                .putAlias(AliasMetaData.builder("bb").build())
+        ).build();
+        List<AliasMetaData> aliases =
+            metaData.findAliases(new GetAliasesRequest().aliases("a*", "-*b", "b*"), new String[] {"index"}).get("index");
+        assertThat(aliases.size(), equalTo(2));
+        assertThat(aliases.get(0).alias(), equalTo("aa"));
+        assertThat(aliases.get(1).alias(), equalTo("bb"));
+    }
+
     public void testIndexAndAliasWithSameName() {
         IndexMetaData.Builder builder = IndexMetaData.builder("index")
                 .settings(Settings.builder().put(IndexMetaData.SETTING_VERSION_CREATED, Version.CURRENT))