[8.13](backport #38181) x-pack/filebeat/input/{cel,websocket}: prevent addition of regexp extension when no patterns are provided

CHANGELOG.next.asciidoc

@@ -97,6 +97,7 @@ fields added to events containing the Beats version. {pull}37553[37553]
 - Fix file handle leak when handling errors in filestream {pull}37973[37973]
 - Fix a race condition that could crash Filebeat with a "negative WaitGroup counter" error {pull}38094[38094]
 - Fix "failed processing S3 event for object key" error on aws-s3 input when key contains the "+" character {issue}38012[38012] {pull}38125[38125]
+- Fix duplicated addition of regexp extension in CEL input. {pull}38181[38181]
 
 *Heartbeat*
 

x-pack/filebeat/input/cel/config_test.go

@@ -12,6 +12,7 @@ import (
 	"os"
 	"reflect"
 	"testing"
+	"time"
 
 	"github.com/google/go-cmp/cmp"
 	"golang.org/x/oauth2/google"
@@ -38,6 +39,19 @@ func TestGetProviderIsCanonical(t *testing.T) {
 	}
 }
 
+func TestRegexpConfig(t *testing.T) {
+	cfg := config{
+		Interval: time.Minute,
+		Program:  `{}`,
+		Resource: &ResourceConfig{URL: &urlConfig{URL: &url.URL{}}},
+		Regexps:  map[string]string{"regex_cve": `[Cc][Vv][Ee]-[0-9]{4}-[0-9]{4,7}`},
+	}
+	err := cfg.Validate()
+	if err != nil {
+		t.Errorf("failed to validate config with regexps: %v", err)
+	}
+}
+
 func TestIsEnabled(t *testing.T) {
 	type enabler interface {
 		isEnabled() bool

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

@@ -918,7 +918,6 @@
 		lib.Debug(debug(log, trace)),
 		lib.File(mimetypes),
 		lib.MIME(mimetypes),
-		lib.Regexp(patterns),
 		lib.Limit(limitPolicies),
 		lib.Globals(map[string]interface{}{
 			"useragent": userAgent,
@@ -1157,7 +1156,7 @@
 // walkMap walks to all ends of the provided path in m and applies fn to the
 // final element of each walk. Nested arrays are not handled.
 func walkMap(m mapstr.M, path string, fn func(parent mapstr.M, key string)) {
 	key, rest, more := strings.Cut(path, ".")
 	v, ok := m[key]
 	if !ok {
 		return

x-pack/filebeat/input/websocket/cel.go

@@ -63,11 +63,13 @@ func newProgram(ctx context.Context, src, root string, patterns map[string]*rege
 		lib.Try(),
 		lib.Debug(debug(log)),
 		lib.MIME(mimetypes),
-		lib.Regexp(patterns),
 		lib.Globals(map[string]interface{}{
 			"useragent": userAgent,
 		}),
 	}
+	if len(patterns) != 0 {
+		opts = append(opts, lib.Regexp(patterns))
+	}
 
 	env, err := cel.NewEnv(opts...)
 	if err != nil {

x-pack/filebeat/input/websocket/config_test.go

@@ -6,6 +6,7 @@ package websocket
 
 import (
 	"fmt"
+	"net/url"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -119,3 +120,15 @@ func TestConfig(t *testing.T) {
 		})
 	}
 }
+
+func TestRegexpConfig(t *testing.T) {
+	cfg := config{
+		Program: `{}`,
+		URL:     &urlConfig{URL: &url.URL{Scheme: "ws"}},
+		Regexps: map[string]string{"regex_cve": `[Cc][Vv][Ee]-[0-9]{4}-[0-9]{4,7}`},
+	}
+	err := cfg.Validate()
+	if err != nil {
+		t.Errorf("failed to validate config with regexps: %v", err)
+	}
+}