[filebeat][s3] Add custom parsing script for S3 notifications (#28946)

* Add custom parsing script for S3 notifications

* Remove unnecessary custom jsmapstr type.
It can be used as a regular JS map since its only purpose is to be read.

* add docs and changelog entry

* Remove commented code

* Document script options restriction

* Better error if Records are missing in notification

* Fix test

* Pass notification as string and add xml parsing options for the scripts

(cherry picked from commit df3fcec)

CHANGELOG.next.asciidoc

@@ -329,6 +329,8 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Sophos UTM: Support logs containing hostname in syslog header. {pull}28638[28638]
 - Moving Oracle Filebeat module to GA. {pull}28754[28754]
 - Add support in aws-s3 input for s3 notification from SNS to SQS. {pull}28800[28800]
+- Add support in aws-s3 input for custom script parsing of s3 notifications. {pull}28946[28946]
+- Improve error handling in aws-s3 input for malformed s3 notifications. {issue}28828[28828] {pull}28946[28946]
 
 *Heartbeat*
 

x-pack/filebeat/docs/inputs/input-aws-s3.asciidoc

@@ -282,6 +282,90 @@ attribute. The default value is 5.
 If you have configured a dead letter queue then you can set this value to
 `-1` to disable deletion on failure.
 
+[float]
+==== `sqs.notification_parsing_script.source`
+
+Inline Javascript source code.
+
+[source,yaml]
+----
+sqs.notification_parsing_script.source: >
+  function parse(notification) {
+      var evts = [];
+      var evt = new S3EventV2();
+      evt.SetS3BucketName(notification.bucket);
+      evt.SetS3ObjectKey(notification.path);
+      evts.push(evt);
+      return evts;
+  }
+----
+
+[float]
+==== `sqs.notification_parsing_script.file`
+
+Path to a script file to load. Relative paths are interpreted as
+relative to the `path.config` directory. Globs are expanded.
+
+This loads `filter.js` from disk.
+
+[source,yaml]
+----
+sqs.notification_parsing_script.file: ${path.config}/filter.js
+----
+
+[float]
+==== `sqs.notification_parsing_script.files`
+
+List of script files to load. The scripts are concatenated together.
+Relative paths are interpreted as relative to the `path.config` directory.
+And globs are expanded.
+
+[float]
+==== `sqs.notification_parsing_script.params`
+
+A dictionary of parameters that are passed to the `register` of the
+script.
+
+Parameters can be passed to the script by adding `params` to the config.
+This allows for a script to be made reusable. When using `params` the
+code must define a `register(params)` function to receive the parameters.
+
+[source,yaml]
+----
+sqs.notification_parsing_script:
+  params:
+    provider: aws:s3
+  source: >
+    var params = {provider: ""};
+    function register(scriptParams) {
+      params = scriptParams;
+    }
+    function parse(notification) {
+      var evts = [];
+      var evt = new S3EventV2();
+      evt.SetS3BucketName(notification.bucket);
+      evt.SetS3ObjectKey(notification.path);
+      evt.SetProvider(params.provider);
+      evts.push(evt);
+      return evts;
+    }
+----
+
+[float]
+==== `sqs.notification_parsing_script.timeout`
+
+This sets an execution timeout for the `process` function. When
+the `process` function takes longer than the `timeout` period the function
+is interrupted. You can set this option to prevent a script from running for
+too long (like preventing an infinite `while` loop). By default there is no
+timeout.
+
+[float]
+==== `sqs.notification_parsing_script.max_cached_sessions`
+
+This sets the maximum number of Javascript VM sessions
+that will be cached to avoid reallocation.
+
 [float]
 ==== `sqs.wait_time`
 
@@ -426,6 +510,177 @@ Therefore, when using the polling list of S3 bucket objects method, scaling shou
 vertical, with a single bigger {beatname_uc} instance and higher `number_of_workers`
 config value.
 
+[float]
+=== SQS Custom Notification Parsing Script
+
+Under some circumstances you might want to listen to events that are not following
+the standard SQS notifications format. To be able to parse them, it is possible to
+define a custom script that will take care of processing them and generating the
+required list of S3 Events used to download the files.
+
+The `sqs.notification_parsing_script` executes Javascript code to process an event.
+It uses a pure Go implementation of ECMAScript 5.1 and has no external dependencies.
+
+It can be configured by embedding Javascript in your configuration file or by pointing
+the processor at external file(s). Only one of the options `sqs.notification_parsing_script.source`, `sqs.notification_parsing_script.file`, and `sqs.notification_parsing_script.files`
+can be set at the same time.
+
+The script requires a `parse(notification)` function that receives the notification as
+a raw string and returns a list of `S3EventV2` objects. This raw string can then be
+processed as needed, e.g.: `JSON.parse(n)` or the provided helper for XML `new XMLDecoder(n)`.
+
+If the script defines a `test()` function it will be invoked when it is loaded. Any exceptions thrown will cause the processor to fail to load. This can be used to make assertions about the behavior of the script.
+
+[source,javascript]
+----
+function parse(n) {
+  var m = JSON.parse(n);
+  var evts = [];
+  var files = m.files;
+  var bucket = m.bucket;
+
+  if (!Array.isArray(files) || (files.length == 0) || bucket == null || bucket == "") {
+    return evts;
+  }
+
+  files.forEach(function(f){
+    var evt = new S3EventV2();
+    evt.SetS3BucketName(bucket);
+    evt.SetS3ObjectKey(f.path);
+    evts.push(evt);
+  });
+
+  return evts;
+}
+
+function test() {
+    var events = parse({bucket: "aBucket", files: [{path: "path/to/file"}]});
+    if (events.length !== 1) {
+      throw "expecting one event";
+    }
+    if (events[0].S3.Bucket.Name === "aBucket") {
+        throw "expected bucket === aBucket";
+    }
+    if (events[0].S3.Object.Key === "path/to/file") {
+        throw "expected bucket === path/to/file";
+    }
+}
+----
+
+[float]
+==== S3EventV2 API
+
+The `S3EventV2` object returned by the `parse` method.
+
+[frame="topbot",options="header"]
+|===
+|Method |Description
+
+|`new S3EventV2()`
+|Returns a new `S3EventV2` object.
+
+*Example*: `var evt = new S3EventV2();`
+
+|`SetAWSRegion(string)`
+|Sets the AWS region.
+
+*Example*: `evt.SetAWSRegion("us-east-1");`
+
+|`SetProvider(string)`
+|Sets the provider.
+
+*Example*: `evt.SetProvider("provider");`
+
+|`SetEventName(string)`
+|Sets the event name.
+
+*Example*: `evt.SetEventName("event-type");`
+
+|`SetEventSource(string)`
+|Sets the event surce.
+
+*Example*: `evt.SetEventSource("aws:s3");`
+
+|`SetS3BucketName(string)`
+|Sets the bucket name.
+
+*Example*: `evt.SetS3BucketName("bucket-name");`
+
+|`SetS3BucketARN(string)`
+|Sets the bucket ARN.
+
+*Example*: `evt.SetS3BucketARN("bucket-ARN");`
+
+|`SetS3ObjectKey(string)`
+|Sets the object key.
+
+*Example*: `evt.SetS3ObjectKey("path/to/object");`
+
+|===
+
+In order to be able to retrieve an S3 object successfully, at least `S3.Object.Key`
+and `S3.Bucket.Name` properties must be set (using the provided setters). The other
+properties will be used as metadata in the resulting event when available.
+
+[float]
+==== XMLDecoder API
+
+To help with XML decoding, an `XMLDecoder` class is provided.
+
+Example XML input:
+
+[source,xml]
+-------------------------------------------------------------------------------
+<catalog>
+  <book seq="1">
+    <author>William H. Gaddis</author>
+    <title>The Recognitions</title>
+    <review>One of the great seminal American novels of the 20th century.</review>
+  </book>
+</catalog>
+-------------------------------------------------------------------------------
+
+Will produce the following output:
+
+[source,json]
+-------------------------------------------------------------------------------
+{
+  "catalog": {
+    "book": {
+      "author": "William H. Gaddis",
+      "review": "One of the great seminal American novels of the 20th century.",
+      "seq": "1",
+      "title": "The Recognitions"
+    }
+  }
+}
+-------------------------------------------------------------------------------
+
+[frame="topbot",options="header"]
+|===
+|Method |Description
+
+|`new XMLDecoder(string)`
+|Returns a new `XMLDecoder` object to decode the provided `string`.
+
+*Example*: `var dec = new XMLDecoder(n);`
+
+|`PrependHyphenToAttr()`
+|Causes the Decoder to prepend a hyphen (`-`) to to all XML attribute names.
+
+*Example*: `dec.PrependHyphenToAttr();`
+
+|`LowercaseKeys()`
+|Causes the Decoder to transform all key name to lowercase.
+
+*Example*: `dec.LowercaseKeys();`
+
+|`Decode()`
+|Reads the XML string and return a map containing the data.
+
+*Example*: `var m = dec.Decode();`
+
+|===
 
 [float]
 === Metrics

x-pack/filebeat/input/awss3/config.go

@@ -24,6 +24,7 @@ type config struct {
 	VisibilityTimeout   time.Duration        `config:"visibility_timeout"`
 	SQSWaitTime         time.Duration        `config:"sqs.wait_time"`         // The max duration for which the SQS ReceiveMessage call waits for a message to arrive in the queue before returning.
 	SQSMaxReceiveCount  int                  `config:"sqs.max_receive_count"` // The max number of times a message should be received (retried) before deleting it.
+	SQSScript           *scriptConfig        `config:"sqs.notification_parsing_script"`
 	FIPSEnabled         bool                 `config:"fips_enabled"`
 	MaxNumberOfMessages int                  `config:"max_number_of_messages"`
 	QueueURL            string               `config:"queue_url"`
@@ -151,6 +152,36 @@ func (rc *readerConfig) Validate() error {
 	return nil
 }
 
+type scriptConfig struct {
+	Source            string                 `config:"source"`                               // Inline script to execute.
+	File              string                 `config:"file"`                                 // Source file.
+	Files             []string               `config:"files"`                                // Multiple source files.
+	Params            map[string]interface{} `config:"params"`                               // Parameters to pass to script.
+	Timeout           time.Duration          `config:"timeout" validate:"min=0"`             // Execution timeout.
+	MaxCachedSessions int                    `config:"max_cached_sessions" validate:"min=0"` // Max. number of cached VM sessions.
+}
+
+// Validate returns an error if one (and only one) option is not set.
+func (c scriptConfig) Validate() error {
+	numConfigured := 0
+	for _, set := range []bool{c.Source != "", c.File != "", len(c.Files) > 0} {
+		if set {
+			numConfigured++
+		}
+	}
+
+	switch {
+	case numConfigured == 0:
+		return errors.New("javascript must be defined via 'file', " +
+			"'files', or inline as 'source'")
+	case numConfigured > 1:
+		return errors.New("javascript can be defined in only one of " +
+			"'file', 'files', or inline as 'source'")
+	}
+
+	return nil
+}
+
 func (rc *readerConfig) InitDefaults() {
 	rc.BufferSize = 16 * humanize.KiByte
 	rc.MaxBytes = 10 * humanize.MiByte

x-pack/filebeat/input/awss3/input.go

@@ -186,8 +186,12 @@ func (in *s3Input) createSQSReceiver(ctx v2.Context, client beat.Client) (*sqsRe
 	if len(in.config.FileSelectors) == 0 {
 		fileSelectors = []fileSelectorConfig{{ReaderConfig: in.config.ReaderConfig}}
 	}
+	script, err := newScriptFromConfig(log.Named("sqs_script"), in.config.SQSScript)
+	if err != nil {
+		return nil, err
+	}
 	s3EventHandlerFactory := newS3ObjectProcessorFactory(log.Named("s3"), metrics, s3API, client, fileSelectors)
-	sqsMessageHandler := newSQSS3EventProcessor(log.Named("sqs_s3_event"), metrics, sqsAPI, in.config.VisibilityTimeout, in.config.SQSMaxReceiveCount, s3EventHandlerFactory)
+	sqsMessageHandler := newSQSS3EventProcessor(log.Named("sqs_s3_event"), metrics, sqsAPI, script, in.config.VisibilityTimeout, in.config.SQSMaxReceiveCount, s3EventHandlerFactory)
 	sqsReader := newSQSReader(log.Named("sqs"), metrics, sqsAPI, in.config.MaxNumberOfMessages, sqsMessageHandler)
 
 	return sqsReader, nil

x-pack/filebeat/input/awss3/input_benchmark_test.go

@@ -166,7 +166,7 @@ func benchmarkInputSQS(t *testing.T, maxMessagesInflight int) testing.BenchmarkR
 		conf := makeBenchmarkConfig(t)
 
 		s3EventHandlerFactory := newS3ObjectProcessorFactory(log.Named("s3"), metrics, s3API, client, conf.FileSelectors)
-		sqsMessageHandler := newSQSS3EventProcessor(log.Named("sqs_s3_event"), metrics, sqsAPI, time.Minute, 5, s3EventHandlerFactory)
+		sqsMessageHandler := newSQSS3EventProcessor(log.Named("sqs_s3_event"), metrics, sqsAPI, nil, time.Minute, 5, s3EventHandlerFactory)
 		sqsReader := newSQSReader(log.Named("sqs"), metrics, sqsAPI, maxMessagesInflight, sqsMessageHandler)
 
 		go func() {