ingest: Introduce the dissect processor

docs/reference/ingest/ingest-node.asciidoc

@@ -1049,6 +1049,199 @@ understands this to mean `2016-04-01` as is explained in the <<date-math-index-n
 | `index_name_format`    | no        | yyyy-MM-dd                   | The format to be used when printing the parsed date into the index name. An valid Joda pattern is expected here.
 |======
 
+[[dissect-processor]]
+=== Dissect Processor
+
+Similar to the <<grok-processor,Grok Processor>>, dissect also extracts structured fields out of a single text field
+within a document.  However unlike the <<grok-processor,Grok Processor>>, dissect does not use
+https://en.wikipedia.org/wiki/Regular_expression[Regular Expressions]. This allows dissect's syntax to be simple and for
+some cases faster than the <<grok-processor,Grok Processor>>.
+
+Dissect matches a single text field against a defined pattern.
+
+For example the following pattern:
+[source,txt]
+--------------------------------------------------
+%{clientip} %{ident} %{auth} [%{@timestamp}] \"%{verb} %{request} HTTP/%{httpversion}\" %{status} %{size}
+--------------------------------------------------
+will match a log line of this format:
+[source,txt]
+--------------------------------------------------
+1.2.3.4 - - [30/Apr/1998:22:00:52 +0000] \"GET /english/venues/cities/images/montpellier/18.gif HTTP/1.0\" 200 3171
+--------------------------------------------------
+and result in a document with the following fields:
+[source,js]
+--------------------------------------------------
+"doc": {
+  "_index": "_index",
+  "_type": "_type",
+  "_id": "_id",
+  "_source": {
+    "request": "/english/venues/cities/images/montpellier/18.gif",
+    "auth": "-",
+    "ident": "-",
+    "verb": "GET",
+    "@timestamp": "30/Apr/1998:22:00:52 +0000",
+    "size": "3171",
+    "clientip": "1.2.3.4",
+    "httpversion": "1.0",
+    "status": "200"
+  }
+}
+--------------------------------------------------
+// NOTCONSOLE
+
+A dissect pattern is defined by the parts of the string that will be discarded. In the example above the first part
+to be discarded is a single space. Dissect finds this space, then assigns the value of `clientip` is everything up
+until that space.
+Later dissect matches the `[` and then `]` and then assigns `@timestamp` to everything in-between `[` and `]`.
+Paying special attention the parts of the string to discard will help build successful dissect patterns.
+
+Successful matches require all keys in a pattern to have a value. If any of the `%{keyname}` defined in the pattern do
+not have a value, then an exception is thrown and may be handled by the <<handling-failure-in-pipelines,on_falure>> directive.
+An empty key `%{}` or a <<dissect-modifier-named-skip-key, named skip key>> can be used to match values, but exclude the value from
+the final document. All matched values are represented as string data types. The <<convert-processor, convert processor>>
+may be used to convert to expected data type.
+
+Dissect also supports <<dissect-key-modifiers,key modifiers>> that can change dissect's default
+behavior. For example you can instruct dissect to ignore certain fields, append fields, skip over padding, etc.
+See <<dissect-key-modifiers, below>> for more information.
+
+[[dissect-options]]
+.Dissect Options
+[options="header"]
+|======
+| Name              | Required  | Default  | Description
+| `field`           | yes       | -        | The field to dissect
+| `pattern`         | yes       | -        | The pattern to apply to the field
+| `append_separator`| no        | "" (empty string) | The character(s) that separate the appended fields.
+| `ignore_missing`  | no        | false             | If `true` and `field` does not exist or is `null`, the processor quietly exits without modifying the document
+| `
+|======
+
+[source,js]
+--------------------------------------------------
+{
+  "dissect": {
+    "field": "message",
+    "pattern" : "%{clientip} %{ident} %{auth} [%{@timestamp}] \"%{verb} %{request} HTTP/%{httpversion}\" %{status} %{size}"
+   }
+}
+--------------------------------------------------
+// NOTCONSOLE
+[[dissect-key-modifiers]]
+==== Dissect key modifiers
+Key modifiers can change the default behavior for dissection. Key modifiers may be found on the left or right
+of the `%{keyname}` always inside the `%{` and `}`. For example `%{+keyname ->}` has the append and right padding
+modifiers.
+
+.Dissect Key Modifiers
+[options="header"]
+|======
+| Modifier      | Name               | Position       | Example                      | Description                                                  | Details
+| `->`          | Skip right padding | (far) right    | `%{keyname1->}`  | Skips any repeated characters to the right                   | <<dissect-modifier-skip-right-padding,link>>
+| `+`           | Append             | left           | `%{+keyname} %{+keyname}`    | Appends two or more fields together                          | <<dissect-modifier-append-key,link>>
+| `+` with `/n` | Append with order  | left and right | `%{+keyname/2} %{+keyname/1}` | Appends two or more fields together in the order specified   | <<dissect-modifier-append-key-with-order,link>>
+| `?`           | Named skip key     | left           | `%{?ignoreme}`  | Skips the matched value in the output. Same behavior as `%{}`| <<dissect-modifier-named-skip-key,link>>
+| `*` and `&`   | Reference keys     | left           | `%{*r1} %{&r1}`    | Sets the output key as value of `*` and output value of `&`  | <<dissect-modifier-reference-keys,link>>
+| `
+|======
+
+[[dissect-modifier-skip-right-padding]]
+===== Right padding modifier (`->`)
+
+The algorithm that performs the dissection is very strict in that it requires all characters in the pattern to match
+the source string. For example, the pattern `%{fookey} %{barkey}` (1 space), will match the string "foo{nbsp}bar"
+(1 space), but will not match the string "foo{nbsp}{nbsp}bar" (2 spaces) since the pattern has only 1 space and the
+source string has 2 spaces.
+
+The right padding modifier helps with this case. Adding the right padding modifier to the pattern `%{fookey->} %{barkey}`,
+It will now will match "foo{nbsp}bar" (1 space) and "foo{nbsp}{nbsp}bar" (2 spaces)
+and even "foo{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}bar" (10 spaces).
+
+Use the right padding modifier to allow for repetition of the characters after a `%{keyname->}`.
+
+The right padding modifier may be placed on any key with any other modifiers. It should always be the furthest right
+modifier. For example: `%{+keyname/1->}` and `%{->}`
+
+Right padding modifier example
+|======
+| *Pattern* | `%{ts->} %{level}`
+| *Input*   |  1998-08-10T17:15:42,466{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}WARN
+| *Result*  a|
+* ts = 1998-08-10T17:15:42,466
+* level = WARN
+|======
+
+The right padding modifier may be used with an empty key to help skip unwanted data. For example, the same input string, but wrapped with brackets requires the use of an empty right padded key to achieve the same result.
+
+Right padding modifier with empty key example
+|======
+| *Pattern* | `[%{ts}]%{->}[%{level}]`
+| *Input*   | [1998-08-10T17:15:42,466]{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}{nbsp}[WARN]
+| *Result*  a|
+* ts = 1998-08-10T17:15:42,466
+* level = WARN
+|======
+
+===== Append modifier (`+`)
+[[dissect-modifier-append-key]]
+Dissect supports appending two or more results together for the output.
+Values are appended left to right. An append separator can be specified.
+In this example the append_separator is defined as a space.
+
+Append modifier example
+|======
+| *Pattern* | `%{+name} %{+name} %{+name} %{+name}`
+| *Input*   | john jacob jingleheimer schmidt
+| *Result*  a|
+* name = john jacob jingleheimer schmidt
+|======
+
+===== Append with order modifier (`+` and `/n`)
+[[dissect-modifier-append-key-with-order]]
+Dissect supports appending two or more results together for the output.
+Values are appended based on the order defined (`/n`). An append separator can be specified.
+In this example the append_separator is defined as a comma.
+
+Append with order modifier example
+|======
+| *Pattern* | `%{+name/2} %{+name/4} %{+name/3} %{+name/1}`
+| *Input*   | john jacob jingleheimer schmidt
+| *Result*  a|
+* name = schmidt,john,jingleheimer,jacob
+|======
+
+===== Named skip key (`?`)
+[[dissect-modifier-named-skip-key]]
+Dissect supports ignoring matches in the final result. This can be done with an empty key `%{}`, but for readability
+it may be desired to give that empty key a name. 
+
+Named skip key modifier example
+|======
+| *Pattern* | `%{clientip} %{?ident} %{?auth} [%{@timestamp}]`
+| *Input*   | 1.2.3.4 - - [30/Apr/1998:22:00:52 +0000]
+| *Result*  a|
+* ip = 1.2.3.4
+* @timestamp = 30/Apr/1998:22:00:52 +0000
+|======
+
+===== Reference keys (`*` and `&`)
+[[dissect-modifier-reference-keys]]
+Dissect support using parsed values as the key/value pairings for the structured content. Imagine a system that 
+partially logs in key/value pairs. Reference keys allow you to maintain that key/value relationship.
+
+Reference key modifier example
+|======
+| *Pattern* | `[%{ts}] [%{level}] %{*p1}:%{&p1} %{*p2}:%{&p2}`
+| *Input*   | [2018-08-10T17:15:42,466] [ERR] ip:1.2.3.4 error:REFUSED
+| *Result*  a|
+* ts = 1998-08-10T17:15:42,466
+* level = ERR
+* ip = 1.2.3.4
+* error = REFUSED
+|====== 
+
 [[dot-expand-processor]]
 === Dot Expander Processor
 

modules/ingest-common/build.gradle

@@ -26,6 +26,7 @@ esplugin {
 dependencies {
     compileOnly project(':modules:lang-painless')
     compile project(':libs:grok')
+    compile project(':libs:dissect')
 }
 
 compileJava.options.compilerArgs << "-Xlint:-unchecked,-rawtypes"

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/DissectProcessor.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.elasticsearch.dissect.DissectParser;
+import org.elasticsearch.ingest.AbstractProcessor;
+import org.elasticsearch.ingest.ConfigurationUtils;
+import org.elasticsearch.ingest.IngestDocument;
+import org.elasticsearch.ingest.Processor;
+
+import java.util.Map;
+
+public final class DissectProcessor extends AbstractProcessor {
+
+    public static final String TYPE = "dissect";
+    //package private members for testing
+    final String field;
+    final boolean ignoreMissing;
+    final String pattern;
+    final String appendSeparator;
+    final DissectParser dissectParser;
+
+    DissectProcessor(String tag, String field, String pattern, String appendSeparator, boolean ignoreMissing) {
+        super(tag);
+        this.field = field;
+        this.ignoreMissing = ignoreMissing;
+        this.pattern = pattern;
+        this.appendSeparator = appendSeparator;
+        this.dissectParser = new DissectParser(pattern, appendSeparator);
+    }
+
+    @Override
+    public void execute(IngestDocument ingestDocument) {
+        String input = ingestDocument.getFieldValue(field, String.class, ignoreMissing);
+        if (input == null && ignoreMissing) {
+            return;
+        } else if (input == null) {
+            throw new IllegalArgumentException("field [" + field + "] is null, cannot process it.");
+        }
+        dissectParser.parse(input).forEach(ingestDocument::setFieldValue);
+    }
+
+    @Override
+    public String getType() {
+        return TYPE;
+    }
+
+    public static final class Factory implements Processor.Factory {
+
+        @Override
+        public DissectProcessor create(Map<String, Processor.Factory> registry, String processorTag, Map<String, Object> config) {
+            String field = ConfigurationUtils.readStringProperty(TYPE, processorTag, config, "field");
+            String pattern = ConfigurationUtils.readStringProperty(TYPE, processorTag, config, "pattern");
+            String appendSeparator = ConfigurationUtils.readStringProperty(TYPE, processorTag, config, "append_separator", "");
+            boolean ignoreMissing = ConfigurationUtils.readBooleanProperty(TYPE, processorTag, config, "ignore_missing", false);
+            return new DissectProcessor(processorTag, field, pattern, appendSeparator, ignoreMissing);
+        }
+    }
+}

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

@@ -82,6 +82,7 @@ public Map<String, Processor.Factory> getProcessors(Processor.Parameters paramet
         processors.put(KeyValueProcessor.TYPE, new KeyValueProcessor.Factory());
         processors.put(URLDecodeProcessor.TYPE, new URLDecodeProcessor.Factory());
         processors.put(BytesProcessor.TYPE, new BytesProcessor.Factory());
+        processors.put(DissectProcessor.TYPE, new DissectProcessor.Factory());
         return Collections.unmodifiableMap(processors);
     }
 

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

@@ -0,0 +1,92 @@
+/*
+ * 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.elasticsearch.ElasticsearchParseException;
+import org.elasticsearch.dissect.DissectException;
+import org.elasticsearch.ingest.RandomDocumentPicks;
+import org.elasticsearch.test.ESTestCase;
+import org.hamcrest.Matchers;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.CoreMatchers.notNullValue;
+import static org.hamcrest.Matchers.is;
+
+public class DissectProcessorFactoryTests extends ESTestCase {
+
+    public void testCreate() {
+        DissectProcessor.Factory factory = new DissectProcessor.Factory();
+        String fieldName = RandomDocumentPicks.randomFieldName(random());
+        String processorTag = randomAlphaOfLength(10);
+        String pattern = "%{a},%{b},%{c}";
+        String appendSeparator = ":";
+
+        Map<String, Object> config = new HashMap<>();
+        config.put("field", fieldName);
+        config.put("pattern", pattern);
+        config.put("append_separator", appendSeparator);
+        config.put("ignore_missing", true);
+
+        DissectProcessor processor = factory.create(null, processorTag, config);
+        assertThat(processor.getTag(), equalTo(processorTag));
+        assertThat(processor.field, equalTo(fieldName));
+        assertThat(processor.pattern, equalTo(pattern));
+        assertThat(processor.appendSeparator, equalTo(appendSeparator));
+        assertThat(processor.dissectParser, is(notNullValue()));
+        assertThat(processor.ignoreMissing, is(true));
+    }
+
+    public void testCreateMissingField() {
+        DissectProcessor.Factory factory = new DissectProcessor.Factory();
+        Map<String, Object> config = new HashMap<>();
+        config.put("pattern", "%{a},%{b},%{c}");
+        Exception e = expectThrows(ElasticsearchParseException.class, () -> factory.create(null, "_tag", config));
+        assertThat(e.getMessage(), Matchers.equalTo("[field] required property is missing"));
+    }
+
+    public void testCreateMissingPattern() {
+        DissectProcessor.Factory factory = new DissectProcessor.Factory();
+        Map<String, Object> config = new HashMap<>();
+        config.put("field", randomAlphaOfLength(10));
+        Exception e = expectThrows(ElasticsearchParseException.class, () -> factory.create(null, "_tag", config));
+        assertThat(e.getMessage(), Matchers.equalTo("[pattern] required property is missing"));
+    }
+
+    public void testCreateMissingOptionals() {
+        DissectProcessor.Factory factory = new DissectProcessor.Factory();
+        Map<String, Object> config = new HashMap<>();
+        config.put("pattern", "%{a},%{b},%{c}");
+        config.put("field", randomAlphaOfLength(10));
+        DissectProcessor processor = factory.create(null, "_tag", config);
+        assertThat(processor.appendSeparator, equalTo(""));
+        assertThat(processor.ignoreMissing, is(false));
+    }
+
+    public void testCreateBadPattern() {
+        DissectProcessor.Factory factory = new DissectProcessor.Factory();
+        Map<String, Object> config = new HashMap<>();
+        config.put("pattern", "no keys defined");
+        config.put("field", randomAlphaOfLength(10));
+        expectThrows(DissectException.class, () -> factory.create(null, "_tag", config));
+    }
+}