Error on deprecated nGram and edgeNGram custom filters

The camel-case `nGram` and `edgeNGram` filter names were deprecated in 6. We
currently throw errors on new indices when they are used. However these errors
are currently only thrown for pre-configured filters, adding them as custom
filters doesn't trigger the warning and error. This change adds the appropriate
exceptions for `nGram` and `edgeNGram` respectively.

Closes elastic#50360

modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/CommonAnalysisPlugin.java

@@ -118,9 +118,11 @@
 import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
 import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.common.regex.Regex;
+import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.xcontent.NamedXContentRegistry;
 import org.elasticsearch.env.Environment;
 import org.elasticsearch.env.NodeEnvironment;
+import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.analysis.AnalyzerProvider;
 import org.elasticsearch.index.analysis.CharFilterFactory;
 import org.elasticsearch.index.analysis.PreBuiltAnalyzerProviderFactory;
@@ -242,7 +244,17 @@ public Map<String, AnalysisProvider<TokenFilterFactory>> getTokenFilters() {
         filters.put("dictionary_decompounder", requiresAnalysisSettings(DictionaryCompoundWordTokenFilterFactory::new));
         filters.put("dutch_stem", DutchStemTokenFilterFactory::new);
         filters.put("edge_ngram", EdgeNGramTokenFilterFactory::new);
-        filters.put("edgeNGram", EdgeNGramTokenFilterFactory::new);
+        filters.put("edgeNGram", (IndexSettings indexSettings, Environment environment, String name, Settings settings) -> {
+            if (indexSettings.getIndexVersionCreated().onOrAfter(org.elasticsearch.Version.V_7_6_0)) {
+                throw new IllegalArgumentException("The [edgeNGram] token filter name was deprecated in 6.4 and "
+                        + "cannot be used in new indices. Please change the filter name to [edge_ngram] instead.");
+            } else {
+                deprecationLogger.deprecatedAndMaybeLog("edgeNGram_deprecation",
+                        "The [edgeNGram] token filter name is deprecated and will be removed in a future version. "
+                                + "Please change the filter name to [edge_ngram] instead.");
+            }
+            return new EdgeNGramTokenFilterFactory(indexSettings, environment, name, settings);
+        });
         filters.put("elision", requiresAnalysisSettings(ElisionTokenFilterFactory::new));
         filters.put("fingerprint", FingerprintTokenFilterFactory::new);
         filters.put("flatten_graph", FlattenGraphTokenFilterFactory::new);
@@ -262,7 +274,17 @@ public Map<String, AnalysisProvider<TokenFilterFactory>> getTokenFilters() {
         filters.put("min_hash", MinHashTokenFilterFactory::new);
         filters.put("multiplexer", MultiplexerTokenFilterFactory::new);
         filters.put("ngram", NGramTokenFilterFactory::new);
-        filters.put("nGram", NGramTokenFilterFactory::new);
+        filters.put("nGram", (IndexSettings indexSettings, Environment environment, String name, Settings settings) -> {
+            if (indexSettings.getIndexVersionCreated().onOrAfter(org.elasticsearch.Version.V_7_6_0)) {
+                throw new IllegalArgumentException("The [nGram] token filter name was deprecated in 6.4 and cannot be used in new indices. "
+                        + "Please change the filter name to [ngram] instead.");
+            } else {
+                deprecationLogger.deprecatedAndMaybeLog("nGram_deprecation",
+                        "The [nGram] token filter name is deprecated and will be removed in a future version. "
+                                + "Please change the filter name to [ngram] instead.");
+            }
+            return new NGramTokenFilterFactory(indexSettings, environment, name, settings);
+        });
         filters.put("pattern_capture", requiresAnalysisSettings(PatternCaptureGroupTokenFilterFactory::new));
         filters.put("pattern_replace", requiresAnalysisSettings(PatternReplaceTokenFilterFactory::new));
         filters.put("persian_normalization", PersianNormalizationFilterFactory::new);

modules/analysis-common/src/test/java/org/elasticsearch/analysis/common/CommonAnalysisPluginTests.java

@@ -127,6 +127,74 @@ public void testEdgeNGramDeprecationError() throws IOException {
                     ex.getMessage());
         }
     }
+
+    /**
+     * Check that the deprecated "nGram" filter throws exception for indices created since 7.0.0 and
+     * logs a warning for earlier indices when the filter is used as a custom filter
+     */
+    public void testnGramFilterInCustomAnalyzerDeprecationError() throws IOException {
+        final Settings settings = Settings.builder().put(Environment.PATH_HOME_SETTING.getKey(), createTempDir())
+            .put(IndexMetaData.SETTING_VERSION_CREATED,
+                VersionUtils.randomVersionBetween(random(), Version.V_7_6_0, Version.CURRENT))
+            .put("index.analysis.analyzer.custom_analyzer.type", "custom")
+            .put("index.analysis.analyzer.custom_analyzer.tokenizer", "standard")
+            .putList("index.analysis.analyzer.custom_analyzer.filter", "my_ngram")
+            .put("index.analysis.filter.my_ngram.type", "nGram")
+            .build();
+
+        final CommonAnalysisPlugin commonAnalysisPlugin = new CommonAnalysisPlugin();
+        IllegalArgumentException ex = expectThrows(IllegalArgumentException.class,
+            () -> createTestAnalysis(IndexSettingsModule.newIndexSettings("index", settings), settings, commonAnalysisPlugin));
+        assertEquals("The [nGram] token filter name was deprecated in 6.4 and cannot be used in new indices. "
+                + "Please change the filter name to [ngram] instead.", ex.getMessage());
+
+        final Settings settingsPre7 = Settings.builder().put(Environment.PATH_HOME_SETTING.getKey(), createTempDir())
+                .put(IndexMetaData.SETTING_VERSION_CREATED,
+                    VersionUtils.randomVersionBetween(random(), Version.V_6_0_0, Version.V_7_5_2))
+                .put("index.analysis.analyzer.custom_analyzer.type", "custom")
+                .put("index.analysis.analyzer.custom_analyzer.tokenizer", "standard")
+                .putList("index.analysis.analyzer.custom_analyzer.filter", "my_ngram")
+                .put("index.analysis.filter.my_ngram.type", "nGram")
+                .build();
+
+        createTestAnalysis(IndexSettingsModule.newIndexSettings("index", settingsPre7), settingsPre7, commonAnalysisPlugin);
+        assertWarnings("The [nGram] token filter name is deprecated and will be removed in a future version. "
+                + "Please change the filter name to [ngram] instead.");
+    }
+
+    /**
+     * Check that the deprecated "edgeNGram" filter throws exception for indices created since 7.0.0 and
+     * logs a warning for earlier indices when the filter is used as a custom filter
+     */
+    public void testEdgeNGramFilterInCustomAnalyzerDeprecationError() throws IOException {
+        final Settings settings = Settings.builder().put(Environment.PATH_HOME_SETTING.getKey(), createTempDir())
+            .put(IndexMetaData.SETTING_VERSION_CREATED,
+                VersionUtils.randomVersionBetween(random(), Version.V_7_6_0, Version.CURRENT))
+            .put("index.analysis.analyzer.custom_analyzer.type", "custom")
+            .put("index.analysis.analyzer.custom_analyzer.tokenizer", "standard")
+            .putList("index.analysis.analyzer.custom_analyzer.filter", "my_ngram")
+            .put("index.analysis.filter.my_ngram.type", "edgeNGram")
+            .build();
+
+        final CommonAnalysisPlugin commonAnalysisPlugin = new CommonAnalysisPlugin();
+        IllegalArgumentException ex = expectThrows(IllegalArgumentException.class,
+            () -> createTestAnalysis(IndexSettingsModule.newIndexSettings("index", settings), settings, commonAnalysisPlugin));
+        assertEquals("The [edgeNGram] token filter name was deprecated in 6.4 and cannot be used in new indices. "
+                + "Please change the filter name to [edge_ngram] instead.", ex.getMessage());
+
+        final Settings settingsPre7 = Settings.builder().put(Environment.PATH_HOME_SETTING.getKey(), createTempDir())
+                .put(IndexMetaData.SETTING_VERSION_CREATED,
+                    VersionUtils.randomVersionBetween(random(), Version.V_6_0_0, Version.V_7_5_2))
+                .put("index.analysis.analyzer.custom_analyzer.type", "custom")
+                .put("index.analysis.analyzer.custom_analyzer.tokenizer", "standard")
+                .putList("index.analysis.analyzer.custom_analyzer.filter", "my_ngram")
+                .put("index.analysis.filter.my_ngram.type", "edgeNGram")
+                .build();
+
+        createTestAnalysis(IndexSettingsModule.newIndexSettings("index", settingsPre7), settingsPre7, commonAnalysisPlugin);
+        assertWarnings("The [edgeNGram] token filter name is deprecated and will be removed in a future version. "
+                + "Please change the filter name to [edge_ngram] instead.");
+    }
 
     /**
      * Check that the deprecated analyzer name "standard_html_strip" throws exception for indices created since 7.0.0