Add HTML strip processor (#41888)

This processor uses the lucene HTMLStripCharFilter class to remove HTML
entities from a field. This adds to the char filter, so that there is
possibility to store the stripped version as well.

Note, that the characeter filter replaces tags with a newline, so that
the produced HTML will look slightly different than the incoming HTML
with regards to newlines.

docs/reference/ingest/ingest-node.asciidoc

@@ -864,6 +864,7 @@ include::processors/foreach.asciidoc[]
 include::processors/geoip.asciidoc[]
 include::processors/grok.asciidoc[]
 include::processors/gsub.asciidoc[]
+include::processors/html_strip.asciidoc[]
 include::processors/join.asciidoc[]
 include::processors/json.asciidoc[]
 include::processors/kv.asciidoc[]

docs/reference/ingest/processors/html_strip.asciidoc

@@ -0,0 +1,26 @@
+[[htmlstrip-processor]]
+=== HTML Strip Processor
+Removes HTML from field.
+
+NOTE: Each HTML tag is replaced with a `\n` character.
+
+[[htmlstrip-options]]
+.HTML Strip Options
+[options="header"]
+|======
+| Name              | Required  | Default  | Description
+| `field`           | yes       | -        | The string-valued field to remove HTML tags from
+| `target_field`    | no        | `field`  | The field to assign the value to, by default `field` is updated in-place
+| `ignore_missing`  | no        | `false`  | If `true` and `field` does not exist, the processor quietly exits without modifying the document
+include::common-options.asciidoc[]
+|======
+
+[source,js]
+--------------------------------------------------
+{
+  "html_strip": {
+    "field": "foo"
+  }
+}
+--------------------------------------------------
+// NOTCONSOLE

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/HtmlStripProcessor.java

@@ -0,0 +1,76 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.ingest.common;
+
+import org.apache.lucene.analysis.charfilter.HTMLStripCharFilter;
+import org.elasticsearch.ElasticsearchException;
+
+import java.io.IOException;
+import java.io.StringReader;
+import java.util.Map;
+
+public final class HtmlStripProcessor extends AbstractStringProcessor<String> {
+
+    public static final String TYPE = "html_strip";
+
+    HtmlStripProcessor(String tag, String field, boolean ignoreMissing, String targetField) {
+        super(tag, field, ignoreMissing, targetField);
+    }
+
+    @Override
+    protected String process(String value) {
+        // shortcut, no need to create a string builder and go through each char
+        if (value.contains("<") == false || value.contains(">") == false) {
+            return value;
+        }
+
+        HTMLStripCharFilter filter = new HTMLStripCharFilter(new StringReader(value));
+
+        StringBuilder builder = new StringBuilder();
+        int ch;
+        try {
+            while ((ch = filter.read()) != -1) {
+                builder.append((char)ch);
+            }
+        } catch (IOException e) {
+            throw new ElasticsearchException(e);
+        }
+
+        return builder.toString();
+    }
+
+    @Override
+    public String getType() {
+        return TYPE;
+    }
+
+    public static final class Factory extends AbstractStringProcessor.Factory {
+
+        public Factory() {
+            super(TYPE);
+        }
+
+        @Override
+        protected HtmlStripProcessor newProcessor(String tag, Map<String, Object> config, String field,
+                                             boolean ignoreMissing, String targetField) {
+            return new HtmlStripProcessor(tag, field, ignoreMissing, targetField);
+        }
+    }
+}

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/IngestCommonPlugin.java

@@ -87,6 +87,7 @@ public class IngestCommonPlugin extends Plugin implements ActionPlugin, IngestPl
         processors.put(PipelineProcessor.TYPE, new PipelineProcessor.Factory(parameters.ingestService));
         processors.put(DissectProcessor.TYPE, new DissectProcessor.Factory());
         processors.put(DropProcessor.TYPE, new DropProcessor.Factory());
+        processors.put(HtmlStripProcessor.TYPE, new HtmlStripProcessor.Factory());
         return Collections.unmodifiableMap(processors);
     }
 

modules/ingest-common/src/test/java/org/elasticsearch/ingest/common/HtmlStripProcessorFactoryTests.java

@@ -0,0 +1,27 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.ingest.common;
+
+public class HtmlStripProcessorFactoryTests extends AbstractStringProcessorFactoryTestCase {
+    @Override
+    protected AbstractStringProcessor.Factory newFactory() {
+        return new HtmlStripProcessor.Factory();
+    }
+}

modules/ingest-common/src/test/java/org/elasticsearch/ingest/common/HtmlStripProcessorTests.java

@@ -0,0 +1,38 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.ingest.common;
+
+public class HtmlStripProcessorTests extends AbstractStringProcessorTestCase<String> {
+
+    @Override
+    protected AbstractStringProcessor<String> newProcessor(String field, boolean ignoreMissing, String targetField) {
+        return new HtmlStripProcessor(randomAlphaOfLength(10), field, ignoreMissing, targetField);
+    }
+
+    @Override
+    protected String modifyInput(String input) {
+        return "<p><b>test</b>" + input + "<p><b>test</b>";
+    }
+
+    @Override
+    protected String expectedResult(String input) {
+        return "\ntest" + input + "\ntest";
+    }
+}

modules/ingest-common/src/test/resources/rest-api-spec/test/ingest/10_basic.yml

@@ -23,6 +23,7 @@
     - contains:  { nodes.$master.ingest.processors: { type: foreach } }
     - contains:  { nodes.$master.ingest.processors: { type: grok } }
     - contains:  { nodes.$master.ingest.processors: { type: gsub } }
+    - contains:  { nodes.$master.ingest.processors: { type: html_strip } }
     - contains:  { nodes.$master.ingest.processors: { type: join } }
     - contains:  { nodes.$master.ingest.processors: { type: json } }
     - contains:  { nodes.$master.ingest.processors: { type: kv } }

modules/ingest-common/src/test/resources/rest-api-spec/test/ingest/40_mutate.yml

@@ -76,6 +76,11 @@ teardown:
                   "pattern" : "-",
                   "replacement" : "."
                 }
+              },
+              {
+                "html_strip" : {
+                  "field" : "field_to_html_strip"
+                }
               }
             ]
           }
@@ -96,7 +101,8 @@ teardown:
             "field_to_split": "127-0-0-1",
             "field_to_join": ["127","0","0","1"],
             "field_to_convert": ["127","0","0","1"],
-            "field_to_gsub": "127-0-0-1"
+            "field_to_gsub": "127-0-0-1",
+            "field_to_html_strip": "<p>this <title>is</title> a <b>test</b>"
           }
 
   - do:
@@ -114,6 +120,7 @@ teardown:
   - match: { _source.field_to_join: "127-0-0-1" }
   - match: { _source.field_to_convert: [127,0,0,1] }
   - match: { _source.field_to_gsub: "127.0.0.1" }
+  - match: { _source.field_to_html_strip: "\nthis \nis\n a test" }
 
 ---
 "Test metadata":