x-pack/filebeat/input/cel: add ability to remove request trace logs

CHANGELOG.next.asciidoc

@@ -280,6 +280,7 @@ https://github.com/elastic/beats/compare/v8.8.1\...main[Check the HEAD diff]
 - Add request trace support for Okta and EntraID entity analytics providers. {pull}39821[39821]
 - Fix handling of infinite rate values in CEL rate limit handling logic. {pull}39940[39940]
 - Allow elision of set and append failure logging. {issue}34544[34544] {pull}39929[39929]
+- Add ability to remove request trace logs from CEL input. {pull}39969[39969]
 
 *Auditbeat*
 

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

@@ -675,17 +675,23 @@ The value of the response that specifies the maximum overall resource request ra
 The maximum burst size. Burst is the maximum number of resource requests that can be made above the overall rate limit.
 
 [float]
-==== `resource.tracer.filename`
+==== `resource.tracer.enable`
 
 It is possible to log HTTP requests and responses in a CEL program to a local file-system for debugging configurations.
-This option is enabled by setting the `resource.tracer.filename` value. Additional options are available to
-tune log rotation behavior.
-
-To differentiate the trace files generated from different input instances, a placeholder `*` can be added to the filename and will be replaced with the input instance id.
-For Example, `http-request-trace-*.ndjson`.
+This option is enabled by setting `resource.tracer.enabled` to true and setting the `resource.tracer.filename` value.
+Additional options are available to tune log rotation behavior. To delete existing logs, set `resource.tracer.enabled`
+to false without unsetting the filename option.
 
 Enabling this option compromises security and should only be used for debugging.
 
+[float]
+==== `resource.tracer.filename`
+
+To differentiate the trace files generated from different input instances, a placeholder `*` can be added to the
+filename and will be replaced with the input instance id. For Example, `http-request-trace-*.ndjson`. Setting
+`resource.tracer.filename` with `resource.tracer.enable` set to false will cause any existing trace logs matching
+the filename option to be deleted.
+
 [float]
 ==== `resource.tracer.maxsize`
 

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

@@ -217,7 +217,16 @@ type ResourceConfig struct {
 
 	Transport httpcommon.HTTPTransportSettings `config:",inline"`
 
-	Tracer *lumberjack.Logger `config:"tracer"`
+	Tracer *tracerConfig `config:"tracer"`
+}
+
+type tracerConfig struct {
+	Enabled           *bool `config:"enabled"`
+	lumberjack.Logger `config:",inline"`
+}
+
+func (t *tracerConfig) enabled() bool {
+	return t != nil && (t.Enabled == nil || *t.Enabled)
 }
 
 type urlConfig struct {

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

@@ -13,9 +13,11 @@
 	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"net"
 	"net/http"
 	"net/url"
+	"os"
 	"path/filepath"
 	"reflect"
 	"regexp"
@@ -717,6 +719,11 @@
 	return limit, true
 }
 
+// lumberjackTimestamp is a glob expression matching the time format string used
+// by lumberjack when rolling over logs, "2006-01-02T15-04-05.000".
+// https://github.com/natefinch/lumberjack/blob/4cb27fcfbb0f35cb48c542c5ea80b7c1d18933d0/lumberjack.go#L39
+const lumberjackTimestamp = "[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]T[0-9][0-9]-[0-9][0-9]-[0-9][0-9].[0-9][0-9][0-9]"
+
 func newClient(ctx context.Context, cfg config, log *logp.Logger, reg *monitoring.Registry) (*http.Client, *httplog.LoggingRoundTripper, error) {
 	if !wantClient(cfg) {
 		return nil, nil, nil
@@ -740,7 +747,7 @@
 	}
 
 	var trace *httplog.LoggingRoundTripper
-	if cfg.Resource.Tracer != nil {
+	if cfg.Resource.Tracer.enabled() {
 		w := zapcore.AddSync(cfg.Resource.Tracer)
 		go func() {
 			// Close the logger when we are done.
@@ -758,6 +765,25 @@
 		maxSize := cfg.Resource.Tracer.MaxSize * 1e6
 		trace = httplog.NewLoggingRoundTripper(c.Transport, traceLogger, max(0, maxSize-margin), log)
 		c.Transport = trace
+	} else if cfg.Resource.Tracer != nil {
+		// We have a trace log name, but we are not enabled,
+		// so remove all trace logs we own.
+		err = os.Remove(cfg.Resource.Tracer.Filename)
+		if err != nil && !errors.Is(err, fs.ErrNotExist) {
+			log.Errorw("failed to remove request trace log", "path", cfg.Resource.Tracer.Filename, "error", err)
+		}
+		ext := filepath.Ext(cfg.Resource.Tracer.Filename)
+		base := strings.TrimSuffix(cfg.Resource.Tracer.Filename, ext)
+		paths, err := filepath.Glob(base + "-" + lumberjackTimestamp + ext)
+		if err != nil {
+			log.Errorw("failed to collect request trace log path names", "error", err)
+		}
+		for _, p := range paths {
+			err = os.Remove(p)
+			if err != nil && !errors.Is(err, fs.ErrNotExist) {
+				log.Errorw("failed to remove request trace log", "path", p, "error", err)
+			}
+		}
 	}
 
 	if reg != nil {
@@ -1213,7 +1239,7 @@
 // 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/cel/input_test.go

@@ -47,6 +47,7 @@ var inputTests = []struct {
 	wantCursor    []map[string]interface{}
 	wantErr       error
 	wantFile      string
+	wantNoFile    string
 }{
 	// Autonomous tests (no FS or net dependency).
 	{
@@ -1141,6 +1142,102 @@ var inputTests = []struct {
 		},
 		wantFile: filepath.Join("logs", "http-request-trace-test_id_tracer_filename_sanitization.ndjson"),
 	},
+	{
+		name: "tracer_filename_sanitization_enabled",
+		server: func(t *testing.T, h http.HandlerFunc, config map[string]interface{}) {
+			server := httptest.NewServer(h)
+			config["resource.url"] = server.URL
+			t.Cleanup(server.Close)
+		},
+		config: map[string]interface{}{
+			"interval":                 1,
+			"resource.tracer.enabled":  true,
+			"resource.tracer.filename": "logs/http-request-trace-*.ndjson",
+			"state": map[string]interface{}{
+				"fake_now": "2002-10-02T15:00:00Z",
+			},
+			"program": `
+	// Use terse non-standard check for presence of timestamp. The standard
+	// alternative is to use has(state.cursor) && has(state.cursor.timestamp).
+	(!is_error(state.cursor.timestamp) ?
+		state.cursor.timestamp
+	:
+		timestamp(state.fake_now)-duration('10m')
+	).as(time_cursor,
+	string(state.url).parse_url().with_replace({
+		"RawQuery": {"$filter": ["alertCreationTime ge "+string(time_cursor)]}.format_query()
+	}).format_url().as(url, bytes(get(url).Body)).decode_json().as(event, {
+		"events": [event],
+		// Get the timestamp from the event if it exists, otherwise advance a little to break a request loop.
+		// Due to the name of the @timestamp field, we can't use has(), so use is_error().
+		"cursor": [{"timestamp": !is_error(event["@timestamp"]) ? event["@timestamp"] : time_cursor+duration('1s')}],
+
+		// Just for testing, cycle this back into the next state.
+		"fake_now": state.fake_now
+	}))
+	`,
+		},
+		handler: dateCursorHandler(),
+		want: []map[string]interface{}{
+			{"@timestamp": "2002-10-02T15:00:00Z", "foo": "bar"},
+			{"@timestamp": "2002-10-02T15:00:01Z", "foo": "bar"},
+			{"@timestamp": "2002-10-02T15:00:02Z", "foo": "bar"},
+		},
+		wantCursor: []map[string]interface{}{
+			{"timestamp": "2002-10-02T15:00:00Z"},
+			{"timestamp": "2002-10-02T15:00:01Z"},
+			{"timestamp": "2002-10-02T15:00:02Z"},
+		},
+		wantFile: filepath.Join("logs", "http-request-trace-test_id_tracer_filename_sanitization_enabled.ndjson"),
+	},
+	{
+		name: "tracer_filename_sanitization_disabled",
+		server: func(t *testing.T, h http.HandlerFunc, config map[string]interface{}) {
+			server := httptest.NewServer(h)
+			config["resource.url"] = server.URL
+			t.Cleanup(server.Close)
+		},
+		config: map[string]interface{}{
+			"interval":                 1,
+			"resource.tracer.enabled":  false,
+			"resource.tracer.filename": "logs/http-request-trace-*.ndjson",
+			"state": map[string]interface{}{
+				"fake_now": "2002-10-02T15:00:00Z",
+			},
+			"program": `
+	// Use terse non-standard check for presence of timestamp. The standard
+	// alternative is to use has(state.cursor) && has(state.cursor.timestamp).
+	(!is_error(state.cursor.timestamp) ?
+		state.cursor.timestamp
+	:
+		timestamp(state.fake_now)-duration('10m')
+	).as(time_cursor,
+	string(state.url).parse_url().with_replace({
+		"RawQuery": {"$filter": ["alertCreationTime ge "+string(time_cursor)]}.format_query()
+	}).format_url().as(url, bytes(get(url).Body)).decode_json().as(event, {
+		"events": [event],
+		// Get the timestamp from the event if it exists, otherwise advance a little to break a request loop.
+		// Due to the name of the @timestamp field, we can't use has(), so use is_error().
+		"cursor": [{"timestamp": !is_error(event["@timestamp"]) ? event["@timestamp"] : time_cursor+duration('1s')}],
+
+		// Just for testing, cycle this back into the next state.
+		"fake_now": state.fake_now
+	}))
+	`,
+		},
+		handler: dateCursorHandler(),
+		want: []map[string]interface{}{
+			{"@timestamp": "2002-10-02T15:00:00Z", "foo": "bar"},
+			{"@timestamp": "2002-10-02T15:00:01Z", "foo": "bar"},
+			{"@timestamp": "2002-10-02T15:00:02Z", "foo": "bar"},
+		},
+		wantCursor: []map[string]interface{}{
+			{"timestamp": "2002-10-02T15:00:00Z"},
+			{"timestamp": "2002-10-02T15:00:01Z"},
+			{"timestamp": "2002-10-02T15:00:02Z"},
+		},
+		wantNoFile: filepath.Join("logs", "http-request-trace-test_id_tracer_filename_sanitization_disabled*"),
+	},
 	{
 		name:   "pagination_cursor_object",
 		server: newTestServer(httptest.NewServer),
@@ -1625,6 +1722,15 @@ func TestInput(t *testing.T) {
 					t.Errorf("expected log file not found: %v", err)
 				}
 			}
+			if test.wantNoFile != "" {
+				paths, err := filepath.Glob(filepath.Join(tempDir, test.wantNoFile))
+				if err != nil {
+					t.Fatalf("unexpected error calling filepath.Glob(%q): %v", test.wantNoFile, err)
+				}
+				if len(paths) != 0 {
+					t.Errorf("unexpected files found: %v", paths)
+				}
+			}
 		})
 	}
 }