[filebeat][input] - Websocket Input with CEL engine

.github/CODEOWNERS

@@ -121,6 +121,7 @@ CHANGELOG*
 /x-pack/filebeat/input/lumberjack/ @elastic/security-service-integrations
 /x-pack/filebeat/input/netflow/ @elastic/sec-deployment-and-devices
 /x-pack/filebeat/input/o365audit/ @elastic/security-service-integrations
+/x-pack/filebeat/input/websocket/ @elastic/security-service-integrations
 /x-pack/filebeat/module/activemq @elastic/obs-infraobs-integrations
 /x-pack/filebeat/module/aws @elastic/obs-cloud-monitoring
 /x-pack/filebeat/module/awsfargate @elastic/obs-cloud-monitoring

CHANGELOG.next.asciidoc

@@ -189,6 +189,7 @@ Setting environmental variable ELASTIC_NETINFO:false in Elastic Agent pod will d
 - Relax TCP/UDP metric polling expectations to improve metric collection. {pull}37714[37714]
 - Add support for PEM-based Okta auth in HTTPJSON. {pull}37772[37772]
 - Prevent complete loss of long request trace data. {issue}37826[37826] {pull}37836[37836]
+- Added experimental version of the Websocket Input. {pull}37774[37774]
 - Add support for PEM-based Okta auth in CEL. {pull}37813[37813]
 
 *Auditbeat*

NOTICE.txt

@@ -18447,6 +18447,38 @@ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 
+--------------------------------------------------------------------------------
+Dependency : github.com/gorilla/websocket
+Version: v1.4.2
+Licence type (autodetected): BSD-2-Clause
+--------------------------------------------------------------------------------
+
+Contents of probable licence file $GOMODCACHE/github.com/gorilla/websocket@v1.4.2/LICENSE:
+
+Copyright (c) 2013 The Gorilla WebSocket Authors. 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 HOLDER 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/h2non/filetype
 Version: v1.1.1
@@ -41594,38 +41626,6 @@ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 
---------------------------------------------------------------------------------
-Dependency : github.com/gorilla/websocket
-Version: v1.4.2
-Licence type (autodetected): BSD-2-Clause
---------------------------------------------------------------------------------
-
-Contents of probable licence file $GOMODCACHE/github.com/gorilla/websocket@v1.4.2/LICENSE:
-
-Copyright (c) 2013 The Gorilla WebSocket Authors. 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 HOLDER 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/hashicorp/cronexpr
 Version: v1.1.0

go.mod

@@ -213,6 +213,7 @@ require (
 	github.com/googleapis/gax-go/v2 v2.12.0
 	github.com/gorilla/handlers v1.5.1
 	github.com/gorilla/mux v1.8.0
+	github.com/gorilla/websocket v1.4.2
 	github.com/icholy/digest v0.1.22
 	github.com/lestrrat-go/jwx/v2 v2.0.19
 	github.com/otiai10/copy v1.12.0
@@ -299,7 +300,6 @@ require (
 	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510 // indirect
 	github.com/googleapis/enterprise-certificate-proxy v0.2.4 // indirect
 	github.com/googleapis/gnostic v0.5.5 // indirect
-	github.com/gorilla/websocket v1.4.2 // indirect
 	github.com/hashicorp/cronexpr v1.1.0 // indirect
 	github.com/hashicorp/errwrap v1.1.0 // indirect
 	github.com/hashicorp/go-cleanhttp v0.5.2 // indirect

x-pack/filebeat/docs/inputs/input-websocket.asciidoc

@@ -0,0 +1,265 @@
+[role="xpack"]
+
+:type: websocket
+:mito_version: v1.8.0
+:mito_docs: https://pkg.go.dev/github.com/elastic/mito@{mito_version}
+
+[id="{beatname_lc}-input-{type}"]
+=== Websocket Input
+beta[]
+
+The `websocket` input reads messages from a websocket server or api endpoint. This input uses the `CEL engine` and the `mito` library interally to parse and process the messages. Having support for `CEL` allows you to parse and process the messages in a more flexible way. It has many similarities with the `cel` input as to how the `CEL` programs are written but deviates in the way the messages are read and processed. The `websocket` input is a `streaming` input and can only be used to read messages from a websocket server or api endpoint. 
+
+This input supports:
+
+* Auth
+** Basic
+** Bearer 
+** API Key
+
+NOTE: The `websocket` input as of now does not support XML messages. Auto-reconnects are also not supported at the moment so reconnection will occur on input restart.
+
+==== Execution
+
+The execution environment provided for the input includes includes the functions, macros, and global variables provided by the mito library.
+A single JSON object is provided as an input accessible through a `state` variable. `state` contains a `response` map field and may contain arbitrary other fields configured via the input's `state` configuration. If the CEL program saves cursor states between executions of the program, the configured `state.cursor` value will be replaced by the saved cursor prior to execution.
+
+On start the `state` is will be something like this:
+
+["source","json",subs="attributes"]
+----
+{
+    "response": { ... },
+    "cursor": { ... },
+    ...
+}
+----
+The `websocket` input creates a `response` field in the state map and attaches the websocket message to this field. All `CEL` programs written should act on this `response` field. Additional fields may be present at the root of the object and if the program tolerates it, the cursor value may be absent.Only the cursor is persisted over restarts, but all fields in state are retained between iterations of the processing loop except for the produced events array, see below.
+
+If the cursor is present the program should perform and process requests based on its value.
+If cursor is not present the program must have alternative logic to determine what requests to make.
+
+After completion of a program's execution it should return a single object with a structure looking like this:
+
+["source","json",subs="attributes"]
+----
+{
+    "events": [ <1>
+        {...},
+        ...
+    ],
+    "cursor": [ <2>
+        {...},
+        ...
+    ],
+    "want_more": false <3>
+}
+----
+
+<1> The `events` field must be present, but may be empty or null. If it is not empty, it must only have objects as elements.
+The field could be an array or a single object that will be treated as an array with a single element. This depends completely on the websocket server or api endpoint. The `events` field is the array of events to be published to the output. Each event must be a JSON object. 
+
+<2> If `cursor` is present it must be either be a single object or an array with the same length as events; each element _i_ of the `cursor` will be the details for obtaining the events at and beyond event _i_ in the `events` array. If the `cursor` is a single object, it will be the details for obtaining events after the last event in the `events` array and will only be retained on successful publication of all the events in the `events` array.
+
+<3> Unlike in the `cel` input, the `want_more` field is always false. This is because the `websocket` input is a streaming input and will always be ready to receive more messages from the websocket server or api endpoint, however the `CEL` program will only be executed once for each message received.
+
+Example configuration:
+
+["source","yaml",subs="attributes"]
+----
+filebeat.inputs:
+# Read and process simple websocket messages from a local websocket server
+- type: websocket
+  resource.url: ws://localhost:443/v1/stream
+  program: |
+    bytes(state.response).decode_json().as(inner_body,{
+			"events": {
+				"message":  inner_body.encode_json(),
+			}
+		})
+----
+
+==== Debug state logging
+
+The Websocket input will log the complete state after evaluation when logging at the DEBUG level.
+This will include any sensitive or secret information kept in the `state` object, and so DEBUG level logging should not be used in production when sensitive information is retained in the `state` object. See <<websocket-state-redact,`redact`>> configuration parameters for settings to exclude sensitive fields from DEBUG logs.
+
+==== Authentication
+The Websocket input supports authentication via Basic token authentication, Bearer token authentication and authentication via Api-Key. Unlike REST inputs Basic Authentication contains a basic auth token, Bearer Authentication contains a bearer token and Api-Key contains an api key. These token/key values are are added to the request headers and are not exposed to the `state` object. For the Api-Key authentication, the header and value are both configurable since different servers might have different api-key header conventions.
+
+Example configurations with authentication:
+
+["source","yaml",subs="attributes"]
+----
+filebeat.inputs:
+- type: websocket
+  auth.basic_token: "dXNlcjpwYXNzd29yZA=="
+  resource.url: wss://localhost:443/_stream
+----
+
+["source","yaml",subs="attributes"]
+----
+filebeat.inputs:
+- type: websocket
+  auth.bearer_token: "dXNlcjpwYXNzd29yZA=="
+  resource.url: wss://localhost:443/_stream
+----
+
+["source","yaml",subs="attributes"]
+----
+filebeat.inputs:
+- type: websocket
+  auth.api_key:
+    header: "x-api-key"
+    value: "dXNlcjpwYXNzd29yZA=="   
+  resource.url: wss://localhost:443/_stream
+----
+
+[[input-state-websocket]]
+==== Input state
+
+The `websocket` input keeps a runtime state between every message received. This state can be accessed by the CEL program and may contain arbitrary objects.
+The state must contain a `response` map and may contain any object the user wishes to store in it. All objects are stored at runtime, except `cursor`, which has values that are persisted between restarts.
+
+==== Configuration options
+
+The `websocket` input supports the following configuration options plus the
+<<{beatname_lc}-input-{type}-common-options>> described later.
+
+[[program-websocket]]
+[float]
+==== `program`
+
+The CEL program that is executed on each message received. This field should ideally be present but if not the default program given below is used.
+
+["source","yaml",subs="attributes"]
+----
+  program: |
+    bytes(state.response).decode_json().as(inner_body,{
+			"events": {
+				"message":  inner_body.encode_json(),
+			}
+	})
+----
+
+[[state-websocket]]
+[float]
+==== `state`
+
+`state` is an optional object that is passed to the CEL program on the first execution. It is available to the executing program as the `state` variable. Except for the `state.cursor` field, `state` does not persist over restarts.
+
+[[cursor-websocket]]
+[float]
+==== `state.cursor`
+
+The cursor is an object available as `state.cursor` where arbitrary values may be stored. Cursor state is kept between input restarts and updated after each event of a request has been published. When a cursor is used the CEL program must either create a cursor state for each event that is returned by the program, or a single cursor that reflect the cursor for completion of the full set of events.
+
+["source","yaml",subs="attributes"]
+----
+filebeat.inputs:
+# Read and process simple websocket messages from a local websocket server
+- type: websocket
+  resource.url: ws://localhost:443/v1/stream
+  program: |
+    bytes(state.response).as(body, {
+        "events": [body.decode_json().with({
+            "last_requested_at": has(state.cursor) && has(state.cursor.last_requested_at) ?
+                state.cursor.last_requested_at
+            :
+                now
+        })],
+        "cursor": {"last_requested_at": now}
+    })
+----
+
+[[regexp-websocket]]
+[float]
+==== `regexp`
+
+A set of named regular expressions that may be used during a CEL program's execution using the `regexp` extension library. The syntax used for the regular expressions is https://github.com/google/re2/wiki/Syntax[RE2].
+
+["source","yaml",subs="attributes"]
+----
+filebeat.inputs:
+- type: websocket
+  # Define two regular expressions, 'products' and 'solutions' for use during CEL program execution.
+  regexp:
+    products: '(?i)(Elasticsearch|Beats|Logstash|Kibana)'
+    solutions: '(?i)(Search|Observability|Security)'
+----
+
+[[websocket-state-redact]]
+[float]
+==== `redact`
+
+During debug level logging, the `state` object and the resulting evaluation result are included in logs. This may result in leaking of secrets. In order to prevent this, fields may be redacted or deleted from the logged `state`. The `redact` configuration allows users to configure this field redaction behaviour. For safety reasons if the `redact` configuration is missing a warning is logged.
+
+In the case of no-required redaction an empty `redact.fields` configuration should be used to silence the logged warning.
+
+["source","yaml",subs="attributes"]
+----
+- type: websocket
+  redact:
+    fields: ~
+----
+
+As an example, if a user-constructed Basic Authentication request is used in a CEL program the password can be redacted like so
+
+["source","yaml",subs="attributes"]
+----
+filebeat.inputs:
+- type: websocket
+  resource.url: ws://localhost:443/_stream
+  state:
+    user: user@domain.tld
+    password: P@$$W0₹D
+  redact:
+    fields:
+      - password
+    delete: true
+----
+
+Note that fields under the `auth` configuration hierarchy are not exposed to the `state` and so do not need to be redacted. For this reason it is preferable to use these for authentication over the request construction shown above where possible.
+
+[float]
+==== `redact.fields`
+
+This specifies fields in the `state` to be redacted prior to debug logging. Fields listed in this array will be either replaced with a `*` or deleted entirely from messages sent to debug logs.
+
+[float]
+==== `redact.delete`
+
+This specifies whether fields should be replaced with a `*` or deleted entirely from messages sent to debug logs. If delete is `true`, fields will be deleted rather than replaced.
+
+[float]
+=== Metrics
+
+This input exposes metrics under the <<http-endpoint, HTTP monitoring endpoint>>.
+These metrics are exposed under the `/inputs` path. They can be used to
+observe the activity of the input.
+
+[options="header"]
+|=======
+| Metric                    | Description
+| `resource`                | URL or path of the input resource.
+| `cel_eval_errors`         | Number of errors encountered during cel program evaluation.
+| `errors_total`            | Number of errors encountered over the life cycle of the input.
+| `batches_received_total`  | Number of event arrays received.
+| `batches_published_total` | Number of event arrays published.
+| `received_bytes_total`    | Number of bytes received over the life cycle of the input.
+| `events_received_total`   | Number of events received.
+| `events_published_total`  | Number of events published.
+| `cel_processing_time`     | Histogram of the elapsed successful CEL program processing times in nanoseconds.
+| `batch_processing_time`   | Histogram of the elapsed successful batch processing times in nanoseconds (time of receipt to time of ACK for non-empty batches).
+|=======
+
+==== Developer tools
+
+A stand-alone CEL environment that implements the majority of the websocket input's Comment Expression Language functionality is available in the https://github.com/elastic/mito[Elastic Mito] repository. This tool may be used to help develop CEL programs to be used by the input. Installation is available from source by running `go install github.com/elastic/mito/cmd/mito@latest` and requires a Go toolchain.
+
+[id="{beatname_lc}-input-{type}-common-options"]
+include::../../../../filebeat/docs/inputs/input-common-options.asciidoc[]
+
+NOTE: The `websocket` input is currently in beta and might have bugs and other issues. Please report any issues on the https://github.com/elastic/beats[Github] repository.
+
+:type!:

x-pack/filebeat/input/default-inputs/inputs_other.go

@@ -22,6 +22,7 @@ import (
 	"github.com/elastic/beats/v7/x-pack/filebeat/input/lumberjack"
 	"github.com/elastic/beats/v7/x-pack/filebeat/input/o365audit"
 	"github.com/elastic/beats/v7/x-pack/filebeat/input/shipper"
+	"github.com/elastic/beats/v7/x-pack/filebeat/input/websocket"
 	"github.com/elastic/elastic-agent-libs/logp"
 )
 
@@ -39,5 +40,6 @@ func xpackInputs(info beat.Info, log *logp.Logger, store beater.StateStore) []v2
 		awscloudwatch.Plugin(),
 		lumberjack.Plugin(),
 		shipper.Plugin(log, store),
+		websocket.Plugin(log, store),
 	}
 }