* Removed script.default_lang setting and made painless the hardc…

…oded default script language.

** The default script language is now maintained in `Script` class.
* Added `script.legacy.default_lang` setting that controls the default language for scripts that are stored inside documents (for example percolator queries).  This defaults to groovy.
** Added `QueryParseContext#getDefaultScriptLanguage()` that manages the default scripting language. Returns always `painless`, unless loading query/search request in legacy mode then the returns what is configured in `script.legacy.default_lang` setting.
** In the aggregation parsing code added `ParserContext` that also holds the default scripting language like `QueryParseContext`. Most parser don't have access to `QueryParseContext`. This is for scripts in aggregations.
* The `lang` script field is always serialized (toXContent).

Closes elastic#20122

core/src/main/java/org/elasticsearch/index/query/QueryParseContext.java

@@ -25,8 +25,11 @@
 import org.elasticsearch.common.ParsingException;
 import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.common.logging.Loggers;
+import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.indices.query.IndicesQueriesRegistry;
+import org.elasticsearch.script.Script;
+import org.elasticsearch.script.ScriptSettings;
 
 import java.io.IOException;
 import java.util.Objects;
@@ -42,11 +45,18 @@ public class QueryParseContext implements ParseFieldMatcherSupplier {
     private final XContentParser parser;
     private final IndicesQueriesRegistry indicesQueriesRegistry;
     private final ParseFieldMatcher parseFieldMatcher;
+    private final String defaultScriptLanguage;
 
     public QueryParseContext(IndicesQueriesRegistry registry, XContentParser parser, ParseFieldMatcher parseFieldMatcher) {
+        this(Script.DEFAULT_SCRIPT_LANG, registry, parser, parseFieldMatcher);
+    }
+
+    public QueryParseContext(String defaultScriptLanguage, IndicesQueriesRegistry registry, XContentParser parser,
+                             ParseFieldMatcher parseFieldMatcher) {
         this.indicesQueriesRegistry = Objects.requireNonNull(registry, "indices queries registry cannot be null");
         this.parser = Objects.requireNonNull(parser, "parser cannot be null");
         this.parseFieldMatcher = Objects.requireNonNull(parseFieldMatcher, "parse field matcher cannot be null");
+        this.defaultScriptLanguage = defaultScriptLanguage;
     }
 
     public XContentParser parser() {
@@ -127,4 +137,12 @@ public Optional<QueryBuilder> parseInnerQueryBuilder() throws IOException {
     public ParseFieldMatcher getParseFieldMatcher() {
         return parseFieldMatcher;
     }
+
+    /**
+     * Returns the default scripting language, that should be used if scripts don't specify the script language
+     * explicitly.
+     */
+    public String getDefaultScriptLanguage() {
+        return defaultScriptLanguage;
+    }
 }

core/src/main/java/org/elasticsearch/index/query/QueryRewriteContext.java

@@ -28,6 +28,7 @@
 import org.elasticsearch.index.mapper.MapperService;
 import org.elasticsearch.indices.query.IndicesQueriesRegistry;
 import org.elasticsearch.script.ScriptService;
+import org.elasticsearch.script.ScriptSettings;
 
 /**
  * Context object used to rewrite {@link QueryBuilder} instances into simplified version.
@@ -101,9 +102,18 @@ public ClusterState getClusterState() {
 
     /**
      * Returns a new {@link QueryParseContext} that wraps the provided parser, using the ParseFieldMatcher settings that
-     * are configured in the index settings
+     * are configured in the index settings. The default script language will always default to Painless.
      */
     public QueryParseContext newParseContext(XContentParser parser) {
         return new QueryParseContext(indicesQueriesRegistry, parser, indexSettings.getParseFieldMatcher());
     }
+
+    /**
+     * Returns a new {@link QueryParseContext} like {@link #newParseContext(XContentParser)} with the only diffence, that
+     * the default script language will default to what has been set in the 'script.legacy.default_lang' setting.
+     */
+    public QueryParseContext newParseContextWithLegacyScriptLanguage(XContentParser parser) {
+        String defaultScriptLanguage = ScriptSettings.getLegacyDefaultLang(indexSettings.getNodeSettings());
+        return new QueryParseContext(defaultScriptLanguage, indicesQueriesRegistry, parser, indexSettings.getParseFieldMatcher());
+    }
 }

core/src/main/java/org/elasticsearch/index/query/ScriptQueryBuilder.java

@@ -106,7 +106,7 @@ public static Optional<ScriptQueryBuilder> fromXContent(QueryParseContext parseC
                 // skip
             } else if (token == XContentParser.Token.START_OBJECT) {
                 if (parseContext.getParseFieldMatcher().match(currentFieldName, ScriptField.SCRIPT)) {
-                    script = Script.parse(parser, parseContext.getParseFieldMatcher());
+                    script = Script.parse(parser, parseContext.getParseFieldMatcher(), parseContext.getDefaultScriptLanguage());
                 } else {
                     throw new ParsingException(parser.getTokenLocation(), "[script] query does not support [" + currentFieldName + "]");
                 }
@@ -116,7 +116,7 @@ public static Optional<ScriptQueryBuilder> fromXContent(QueryParseContext parseC
                 } else if (parseContext.getParseFieldMatcher().match(currentFieldName, AbstractQueryBuilder.BOOST_FIELD)) {
                     boost = parser.floatValue();
                 } else if (parseContext.getParseFieldMatcher().match(currentFieldName, ScriptField.SCRIPT)) {
-                    script = Script.parse(parser, parseContext.getParseFieldMatcher());
+                    script = Script.parse(parser, parseContext.getParseFieldMatcher(), parseContext.getDefaultScriptLanguage());
                 } else {
                     throw new ParsingException(parser.getTokenLocation(), "[script] query does not support [" + currentFieldName + "]");
                 }

core/src/main/java/org/elasticsearch/index/query/functionscore/ScriptScoreFunctionBuilder.java

@@ -115,7 +115,7 @@ public static ScriptScoreFunctionBuilder fromXContent(QueryParseContext parseCon
                 currentFieldName = parser.currentName();
             } else {
                 if (parseContext.getParseFieldMatcher().match(currentFieldName, ScriptField.SCRIPT)) {
-                    script = Script.parse(parser, parseContext.getParseFieldMatcher());
+                    script = Script.parse(parser, parseContext.getParseFieldMatcher(), parseContext.getDefaultScriptLanguage());
                 } else {
                     throw new ParsingException(parser.getTokenLocation(), NAME + " query does not support [" + currentFieldName + "]");
                 }

core/src/main/java/org/elasticsearch/script/Script.java

@@ -44,6 +44,7 @@
 public final class Script implements ToXContent, Writeable {
 
     public static final ScriptType DEFAULT_TYPE = ScriptType.INLINE;
+    public static final String DEFAULT_SCRIPT_LANG = "painless";
 
     private String script;
     private ScriptType type;
@@ -60,7 +61,7 @@ public Script(String script) {
         this(script, ScriptType.INLINE, null, null);
     }
 
-    public Script(String script, ScriptType type, @Nullable String lang, @Nullable Map<String, ?> params) {
+    public Script(String script, ScriptType type, String lang, @Nullable Map<String, ?> params) {
         this(script, type, lang, params, null);
     }
 
@@ -78,14 +79,14 @@ public Script(String script, ScriptType type, @Nullable String lang, @Nullable M
      *                      when serializing the script back to xcontent.
      */
     @SuppressWarnings("unchecked")
-    public Script(String script, ScriptType type, @Nullable String lang, @Nullable Map<String, ?> params,
+    public Script(String script, ScriptType type, String lang, @Nullable Map<String, ?> params,
                   @Nullable XContentType  contentType) {
         if (contentType != null && type != ScriptType.INLINE) {
             throw new IllegalArgumentException("The parameter contentType only makes sense for inline scripts");
         }
         this.script = Objects.requireNonNull(script);
         this.type = Objects.requireNonNull(type);
-        this.lang = lang;
+        this.lang = lang == null ? DEFAULT_SCRIPT_LANG : lang;
         this.params = (Map<String, Object>) params;
         this.contentType = contentType;
     }
@@ -135,7 +136,7 @@ public String getScript() {
      * @return The type of script -- inline, stored, or file.
      */
     public ScriptType getType() {
-        return type == null ? DEFAULT_TYPE : type;
+        return type;
     }
 
     /**
@@ -196,7 +197,7 @@ public static Script parse(XContentParser parser, ParseFieldMatcher parseFieldMa
             token = parser.nextToken();
         }
         if (token == XContentParser.Token.VALUE_STRING) {
-            return new Script(parser.text());
+            return new Script(parser.text(), ScriptType.INLINE, lang, null);
         }
         if (token != XContentParser.Token.START_OBJECT) {
             throw new ElasticsearchParseException("expected a string value or an object, but found [{}] instead", token);

core/src/main/java/org/elasticsearch/script/ScriptService.java

@@ -92,8 +92,6 @@ public class ScriptService extends AbstractComponent implements Closeable, Clust
     public static final Setting<Integer> SCRIPT_MAX_COMPILATIONS_PER_MINUTE =
         Setting.intSetting("script.max_compilations_per_minute", 15, 0, Property.Dynamic, Property.NodeScope);
 
-    private final String defaultLang;
-
     private final Collection<ScriptEngineService> scriptEngines;
     private final Map<String, ScriptEngineService> scriptEnginesByLang;
     private final Map<String, ScriptEngineService> scriptEnginesByExt;
@@ -131,8 +129,6 @@ public ScriptService(Settings settings, Environment env,
         this.scriptContextRegistry = scriptContextRegistry;
         int cacheMaxSize = SCRIPT_CACHE_SIZE_SETTING.get(settings);
 
-        this.defaultLang = scriptSettings.getDefaultScriptLanguageSetting().get(settings);
-
         CacheBuilder<CacheKey, CompiledScript> cacheBuilder = CacheBuilder.builder();
         if (cacheMaxSize >= 0) {
             cacheBuilder.setMaximumWeight(cacheMaxSize);
@@ -222,11 +218,6 @@ public CompiledScript compile(Script script, ScriptContext scriptContext, Map<St
         }
 
         String lang = script.getLang();
-
-        if (lang == null) {
-            lang = defaultLang;
-        }
-
         ScriptEngineService scriptEngineService = getScriptEngineServiceForLang(lang);
         if (canExecuteScript(lang, script.getType(), scriptContext) == false) {
             throw new IllegalStateException("scripts of type [" + script.getType() + "], operation [" + scriptContext.getKey() + "] and lang [" + lang + "] are disabled");
@@ -285,7 +276,7 @@ CompiledScript compileInternal(Script script, Map<String, String> params) {
             throw new IllegalArgumentException("The parameter script (Script) must not be null.");
         }
 
-        String lang = script.getLang() == null ? defaultLang : script.getLang();
+        String lang = script.getLang();
         ScriptType type = script.getType();
         //script.getScript() could return either a name or code for a script,
         //but we check for a file script name first and an indexed script name second
@@ -364,9 +355,8 @@ CompiledScript compileInternal(Script script, Map<String, String> params) {
     }
 
     private String validateScriptLanguage(String scriptLang) {
-        if (scriptLang == null) {
-            scriptLang = defaultLang;
-        } else if (scriptEnginesByLang.containsKey(scriptLang) == false) {
+        Objects.requireNonNull(scriptLang);
+        if (scriptEnginesByLang.containsKey(scriptLang) == false) {
             throw new IllegalArgumentException("script_lang not supported [" + scriptLang + "]");
         }
         return scriptLang;

core/src/main/java/org/elasticsearch/script/ScriptSettings.java

@@ -32,7 +32,16 @@
 
 public class ScriptSettings {
 
-    public static final String DEFAULT_LANG = "painless";
+    static final String LEGACY_DEFAULT_LANG = "groovy";
+
+    /**
+     * The default script language to use for scripts that are stored in documents that have no script lang set explicitly.
+     * This setting is legacy setting and only applies for indices created on ES versions prior to version 5.0
+     *
+     * This constant will be removed in the next major release.
+     */
+    @Deprecated
+    public static final String LEGACY_SCRIPT_SETTING = "script.legacy.default_lang";
 
     private static final Map<ScriptService.ScriptType, Setting<Boolean>> SCRIPT_TYPE_SETTING_MAP;
 
@@ -49,7 +58,7 @@ public class ScriptSettings {
 
     private final Map<ScriptContext, Setting<Boolean>> scriptContextSettingMap;
     private final List<Setting<Boolean>> scriptLanguageSettings;
-    private final Setting<String> defaultScriptLanguageSetting;
+    private final Setting<String> defaultLegacyScriptLanguageSetting;
 
     public ScriptSettings(ScriptEngineRegistry scriptEngineRegistry, ScriptContextRegistry scriptContextRegistry) {
         Map<ScriptContext, Setting<Boolean>> scriptContextSettingMap = contextSettings(scriptContextRegistry);
@@ -58,8 +67,8 @@ public ScriptSettings(ScriptEngineRegistry scriptEngineRegistry, ScriptContextRe
         List<Setting<Boolean>> scriptLanguageSettings = languageSettings(SCRIPT_TYPE_SETTING_MAP, scriptContextSettingMap, scriptEngineRegistry, scriptContextRegistry);
         this.scriptLanguageSettings = Collections.unmodifiableList(scriptLanguageSettings);
 
-        this.defaultScriptLanguageSetting = new Setting<>("script.default_lang", DEFAULT_LANG, setting -> {
-            if (!DEFAULT_LANG.equals(setting) && !scriptEngineRegistry.getRegisteredLanguages().containsKey(setting)) {
+        this.defaultLegacyScriptLanguageSetting = new Setting<>(LEGACY_SCRIPT_SETTING, LEGACY_DEFAULT_LANG, setting -> {
+            if (!LEGACY_DEFAULT_LANG.equals(setting) && !scriptEngineRegistry.getRegisteredLanguages().containsKey(setting)) {
                 throw new IllegalArgumentException("unregistered default language [" + setting + "]");
             }
             return setting;
@@ -160,15 +169,19 @@ public List<Setting<?>> getSettings() {
         settings.addAll(SCRIPT_TYPE_SETTING_MAP.values());
         settings.addAll(scriptContextSettingMap.values());
         settings.addAll(scriptLanguageSettings);
-        settings.add(defaultScriptLanguageSetting);
+        settings.add(defaultLegacyScriptLanguageSetting);
         return settings;
     }
 
     public Iterable<Setting<Boolean>> getScriptLanguageSettings() {
         return scriptLanguageSettings;
     }
 
-    public Setting<String> getDefaultScriptLanguageSetting() {
-        return defaultScriptLanguageSetting;
+    public Setting<String> getDefaultLegacyScriptLanguageSetting() {
+        return defaultLegacyScriptLanguageSetting;
+    }
+
+    public static String getLegacyDefaultLang(Settings settings) {
+        return settings.get(LEGACY_SCRIPT_SETTING, ScriptSettings.LEGACY_DEFAULT_LANG);
     }
 }

core/src/main/java/org/elasticsearch/search/aggregations/bucket/geogrid/GeoHashGridParser.java

@@ -19,11 +19,11 @@
 package org.elasticsearch.search.aggregations.bucket.geogrid;
 
 import org.elasticsearch.common.ParseField;
-import org.elasticsearch.common.ParseFieldMatcher;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.common.xcontent.XContentParser.Token;
 import org.elasticsearch.index.query.GeoBoundingBoxQueryBuilder;
 import org.elasticsearch.search.aggregations.support.AbstractValuesSourceParser.GeoPointValuesSourceParser;
+import org.elasticsearch.search.aggregations.support.XContentParseContext;
 import org.elasticsearch.search.aggregations.support.ValueType;
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
 
@@ -65,16 +65,17 @@ protected GeoGridAggregationBuilder createFactory(
     }
 
     @Override
-    protected boolean token(String aggregationName, String currentFieldName, Token token, XContentParser parser,
-            ParseFieldMatcher parseFieldMatcher, Map<ParseField, Object> otherOptions) throws IOException {
+    protected boolean token(String aggregationName, String currentFieldName, Token token,
+                            XContentParseContext context, Map<ParseField, Object> otherOptions) throws IOException {
+        XContentParser parser = context.getParser();
         if (token == XContentParser.Token.VALUE_NUMBER || token == XContentParser.Token.VALUE_STRING) {
-            if (parseFieldMatcher.match(currentFieldName, GeoHashGridParams.FIELD_PRECISION)) {
+            if (context.matchField(currentFieldName, GeoHashGridParams.FIELD_PRECISION)) {
                 otherOptions.put(GeoHashGridParams.FIELD_PRECISION, parser.intValue());
                 return true;
-            } else if (parseFieldMatcher.match(currentFieldName, GeoHashGridParams.FIELD_SIZE)) {
+            } else if (context.matchField(currentFieldName, GeoHashGridParams.FIELD_SIZE)) {
                 otherOptions.put(GeoHashGridParams.FIELD_SIZE, parser.intValue());
                 return true;
-            } else if (parseFieldMatcher.match(currentFieldName, GeoHashGridParams.FIELD_SHARD_SIZE)) {
+            } else if (context.matchField(currentFieldName, GeoHashGridParams.FIELD_SHARD_SIZE)) {
                 otherOptions.put(GeoHashGridParams.FIELD_SHARD_SIZE, parser.intValue());
                 return true;
             }