Add script processor (#10850)

The script processor executes Javascript code to process an event. The processor uses a pure
Go implementation of ECMAScript 5.1. This can be useful in situations where one of the other
processors doesn’t provide the functionality you need to filter events.

The processor can be configured by embedding Javascript in your configuration file or by pointing
the processor at external file(s). See the included documentation for the full details.

    processors:
    - script:
        type: javascript
        code: >
          function process(event) {
              event.Tag("js");
          }

For observability it can add metrics with a histogram of the execution time and a counter
for the number of exceptions that occur.

There is an optional timeout configuration option to the processor that will
timeout the execution by interrupting the JS code.

Rather than have libbeat force the inclusion of the script processor in all Beats, make each Beat opt into the processor. It is imported by the log processing Beats (filebeat, journalbeat, and winlogbeat).

Benchmark Results

Here's a benchmark to get a rough idea of how long it takes to process an event in the processor's runtime

I updated the benchmark to test each case with and without the timeout enabled.

    BenchmarkBeatEventV0/Put-12                         2000000           707 ns/op
    BenchmarkBeatEventV0/timeout_Put-12                 1000000          1510 ns/op
    BenchmarkBeatEventV0/Object_Put_Key-12              2000000           631 ns/op
    BenchmarkBeatEventV0/timeout_Object_Put_Key-12      1000000          1252 ns/op
    BenchmarkBeatEventV0/Get-12                         2000000           750 ns/op
    BenchmarkBeatEventV0/timeout_Get-12                 1000000          1495 ns/op
    BenchmarkBeatEventV0/Get_Undefined_Key-12           1000000          1039 ns/op
    BenchmarkBeatEventV0/timeout_Get_Undefined_Key-12   1000000          2108 ns/op
    BenchmarkBeatEventV0/fields_get_key-12              2000000          1044 ns/op
    BenchmarkBeatEventV0/timeout_fields_get_key-12      1000000          2051 ns/op
    BenchmarkBeatEventV0/Get_@metadata-12               2000000           750 ns/op
    BenchmarkBeatEventV0/timeout_Get_@metadata-12       1000000          1745 ns/op
    BenchmarkBeatEventV0/Put_@metadata-12               1000000          1048 ns/op
    BenchmarkBeatEventV0/timeout_Put_@metadata-12       500000          2623 ns/op
    BenchmarkBeatEventV0/Delete_@metadata-12            2000000           842 ns/op
    BenchmarkBeatEventV0/timeout_Delete_@metadata-12    1000000          1629 ns/op
    BenchmarkBeatEventV0/Cancel-12                      2000000           759 ns/op
    BenchmarkBeatEventV0/timeout_Cancel-12              1000000          1329 ns/op
    BenchmarkBeatEventV0/Tag-12                         1000000          1189 ns/op
    BenchmarkBeatEventV0/timeout_Tag-12                 1000000          1973 ns/op
    BenchmarkBeatEventV0/AppendTo-12                    2000000           644 ns/op
    BenchmarkBeatEventV0/timeout_AppendTo-12            1000000          1347 ns/op

CHANGELOG.next.asciidoc

@@ -242,6 +242,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Add output test to kafka output {pull}10834[10834]
 - Add ip fields to default_field in Elasticsearch template. {pull}11035[11035]
 - Gracefully shut down on SIGHUP {pull}10704[10704]
+- Add `script` processor that supports using Javascript to process events. {pull}10850[10850]
 
 *Auditbeat*
 

NOTICE.txt

@@ -389,6 +389,34 @@ License type (autodetected): Apache-2.0
 Apache License 2.0
 
 
+--------------------------------------------------------------------
+Dependency: github.com/dlclark/regexp2
+Revision: 7632a260cbaf5e7594fc1544a503456ecd0827f1
+License type (autodetected): MIT
+./vendor/github.com/dlclark/regexp2/LICENSE:
+--------------------------------------------------------------------
+The MIT License (MIT)
+
+Copyright (c) Doug Clark
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
 --------------------------------------------------------------------
 Dependency: github.com/docker/distribution
 Revision: 1e2f10eb65743fed02f573d31a4587de09afb20e
@@ -454,6 +482,28 @@ License type (autodetected): Apache-2.0
 Apache License 2.0
 
 
+--------------------------------------------------------------------
+Dependency: github.com/dop251/goja
+Revision: dd2ac4456e2073f116d6b88741d513addabe0326
+License type (autodetected): MIT
+./vendor/github.com/dop251/goja/LICENSE:
+--------------------------------------------------------------------
+Copyright (c) 2016 Dmitry Panov
+
+Copyright (c) 2012 Robert Krimen
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the Software without restriction, including without limitation
+the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
+WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
 --------------------------------------------------------------------
 Dependency: github.com/dustin/go-humanize
 Revision: 259d2a102b871d17f30e3cd9881a642961a1e486
@@ -905,6 +955,38 @@ The above copyright notice and this permission notice shall be included in all c
 
 THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
+--------------------------------------------------------------------
+Dependency: github.com/go-sourcemap/sourcemap
+Revision: b019cc30c1eaa584753491b0d8f8c1534bf1eb44
+License type (autodetected): BSD-2-Clause
+./vendor/github.com/go-sourcemap/sourcemap/LICENSE:
+--------------------------------------------------------------------
+Copyright (c) 2016 The github.com/go-sourcemap/sourcemap Contributors.
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
 --------------------------------------------------------------------
 Dependency: github.com/go-sql-driver/mysql
 Version: v1.4.1

filebeat/cmd/root.go

@@ -26,6 +26,9 @@ import (
 
 	cmd "github.com/elastic/beats/libbeat/cmd"
 	"github.com/elastic/beats/libbeat/cmd/instance"
+
+	// Import the script processor.
+	_ "github.com/elastic/beats/libbeat/processors/script"
 )
 
 // Name of this beat

journalbeat/cmd/root.go

@@ -22,6 +22,9 @@ import (
 
 	cmd "github.com/elastic/beats/libbeat/cmd"
 	"github.com/elastic/beats/libbeat/cmd/instance"
+
+	// Import the script processor.
+	_ "github.com/elastic/beats/libbeat/processors/script"
 )
 
 // Name of this beat

libbeat/common/config.go

@@ -146,7 +146,7 @@ func OverwriteConfigOpts(options []ucfg.Option) {
 
 func LoadFile(path string) (*Config, error) {
 	if IsStrictPerms() {
-		if err := ownerHasExclusiveWritePerms(path); err != nil {
+		if err := OwnerHasExclusiveWritePerms(path); err != nil {
 			return nil, err
 		}
 	}
@@ -414,10 +414,10 @@ func filterDebugObject(c interface{}) {
 	}
 }
 
-// ownerHasExclusiveWritePerms asserts that the current user or root is the
+// OwnerHasExclusiveWritePerms asserts that the current user or root is the
 // owner of the config file and that the config file is (at most) writable by
 // the owner or root (e.g. group and other cannot have write access).
-func ownerHasExclusiveWritePerms(name string) error {
+func OwnerHasExclusiveWritePerms(name string) error {
 	if runtime.GOOS == "windows" {
 		return nil
 	}

libbeat/docs/processors-using.asciidoc

@@ -195,19 +195,22 @@ endif::[]
 The supported processors are:
 
  * <<add-cloud-metadata,`add_cloud_metadata`>>
+ * <<add-docker-metadata,`add_docker_metadata`>>
+ * <<add-host-metadata,`add_host_metadata`>>
+ * <<add-kubernetes-metadata,`add_kubernetes_metadata`>>
  * <<add-locale,`add_locale`>>
+ * <<add-process-metadata,`add_process_metadata`>>
  * <<community-id,`community_id`>>
  * <<decode-json-fields,`decode_json_fields`>>
+ * <<dissect, `dissect`>>
+ * <<processor-dns, `dns`>>
  * <<drop-event,`drop_event`>>
  * <<drop-fields,`drop_fields`>>
  * <<include-fields,`include_fields`>>
  * <<rename-fields,`rename`>>
- * <<add-kubernetes-metadata,`add_kubernetes_metadata`>>
- * <<add-docker-metadata,`add_docker_metadata`>>
- * <<add-host-metadata,`add_host_metadata`>>
- * <<dissect, `dissect`>>
- * <<processor-dns, `dns`>>
- * <<add-process-metadata,`add_process_metadata`>>
+ifeval::[("{beatname_lc}"=="filebeat") or ("{beatname_lc}"=="winlogbeat") or ("{beatname_lc}"=="journalbeat")]
+ * <<processor-script,`script`>>
+endif::[]
 
 [[conditions]]
 ==== Conditions
@@ -1280,3 +1283,174 @@ set to `true`, this condition will be ignored.
 `restricted_fields`:: (Optional) By default, the `process.env` field is not
 output, to avoid leaking sensitive data. If `restricted_fields` is `true`, the
 field will be present in the output.
+
+ifeval::[("{beatname_lc}"=="filebeat") or ("{beatname_lc}"=="winlogbeat") or ("{beatname_lc}"=="journalbeat")]
+[[processor-script]]
+=== Script Processor
+
+experimental[]
+
+The script processor executes Javascript code to process an event. The processor
+uses a pure Go implementation of ECMAScript 5.1 and has no external
+dependencies. This can be useful in situations where one of the other processors
+doesn't provide the functionality you need to filter events.
+
+The processor can be configured by embedding Javascript in your configuration
+file or by pointing the processor at external file(s).
+
+[source,yaml]
+----
+processors:
+- script:
+    lang: javascript
+    id: my_filter
+    source: >
+      function process(event) {
+          event.Tag("js");
+      }
+----
+
+This loads `filter.js` from disk.
+
+[source,yaml]
+----
+processors:
+- script:
+    lang: javascript
+    id: my_filter
+    file: ${path.config}/filter.js
+----
+
+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]
+----
+processors:
+- script:
+    lang: javascript
+    id: my_filter
+    params:
+      threshold: 15
+    source: >
+      var params = {threshold: 42};
+      function register(scriptParams) {
+          params = scriptParams;
+      }
+      function process(event) {
+          if (event.Get("severity") < params.threshold) {
+              event.Cancel();
+          }
+      }
+----
+
+If the script defines a `test()` function it will be invoked when the processor
+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 process(event) {
+    if (event.Get("event.code") === 1102) {
+        event.Put("event.action", "cleared");
+    }
+}
+
+function test() {
+    var event = process(new Event({event: {code: 1102}));
+    if (event.Get("event.action") !== "cleared") {
+        throw "expected event.action === cleared";
+    }
+}
+----
+
+[float]
+==== Configuration options
+
+The `script` processor has the following configuration settings:
+
+`lang`:: This field is required and its value must be `javascript`.
+
+`tag`:: This is an optional identifier that is added to log messages. If defined
+it enables metrics logging for this instance of the processor. The metrics
+include the number of exceptions and a histogram of the execution times for
+the `process` function.
+
+`source`:: Inline Javascript source code.
+
+`file`:: Path to a script file to load. Relative paths are interpreted as
+relative to the `path.config` directory. Globs are expanded.
+
+`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.
+
+`params`:: A dictionary of parameters that are passed to the `register` of the
+script.
+
+`tag_on_exception`:: Tag to add to events in case the Javascript code causes an
+exception while processing an event. Defaults to `_js_exception`.
+
+`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]
+==== Event API
+
+The `Event` object passed to the `process` method has the following API.
+
+[frame="topbot",options="header"]
+|===
+|Method |Description
+
+|`Get(string)`
+|Get a value from the event (either a scalar or an object). If the key does not
+exist `null` is returned. If no key is provided then an object containing all
+fields is returned.
+
+*Example*: `var value = event.Get(key);`
+
+|`Put(string, value)`
+|Put a value into the event. If the key was already set then the
+previous value is returned. It throws an exception if the key cannot be set
+because one of the intermediate values is not an object.
+
+*Example*: `var old = event.Put(key, value);`
+
+|`Rename(string, string)`
+|Rename a key in the event. The target key must not exist. It
+returns true if the source key was successfully renamed to the target key.
+
+*Example*: `var success = event.Rename("source", "target");`
+
+|`Delete(string)`
+|Delete a field from the event. It returns true on success.
+
+*Example*: `var deleted = event.Delete("user.email");`
+
+|`Cancel()`
+|Flag the event as cancelled which causes the processor to drop
+event.
+
+*Example*: `event.Cancel(); return;`
+
+|`Tag(string)`
+|Append a tag to the `tags` field if the tag does not already
+exist. Throws an exception if `tags` exists and is not a string or a list of
+strings.
+
+*Example*: `event.Tag("user_event");`
+
+|`AppendTo(string, string)`
+|`AppendTo` is a specialized `Put` method that converts the existing value to an
+array and appends the value if it does not already exist. If there is an
+existing value that's not a string or array of strings then an exception is
+thrown.
+
+*Example*: `event.AppendTo("error.message", "invalid file hash");`
+|===
+endif::[]