Do not rotate log files on startup when interval is configured and rotateonstartup is disabled

CHANGELOG.next.asciidoc

@@ -74,6 +74,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Fix concurrency issues in convert processor when used in the global context. {pull}17032[17032]
 - Fix bug with `monitoring.cluster_uuid` setting not always being exposed via GET /state Beats API. {issue}16732[16732] {pull}17420[17420]
 - Fix building on FreeBSD by removing build flags from `add_cloudfoundry_metadata` processor. {pull}17486[17486]
+- Do not rotate log files on startup when interval is configured and rotateonstartup is disabled. {pull}17613[17613]
 
 *Auditbeat*
 

libbeat/common/file/interval_rotator.go

@@ -20,8 +20,11 @@ package file
 import (
 	"errors"
 	"fmt"
+	"io/ioutil"
+	"path/filepath"
 	"sort"
 	"strconv"
+	"strings"
 	"time"
 )
 
@@ -45,7 +48,7 @@ func (realClock) Now() time.Time {
 	return time.Now()
 }
 
-func newIntervalRotator(interval time.Duration) (*intervalRotator, error) {
+func newIntervalRotator(log Logger, interval time.Duration, rotateOnStartup bool, filename string) (*intervalRotator, error) {
 	if interval == 0 {
 		return nil, nil
 	}
@@ -54,11 +57,11 @@ func newIntervalRotator(interval time.Duration) (*intervalRotator, error) {
 	}
 
 	ir := &intervalRotator{interval: (interval / time.Second) * time.Second} // drop fractional seconds
-	ir.initialize()
+	ir.initialize(log, rotateOnStartup, filename)
 	return ir, nil
 }
 
-func (r *intervalRotator) initialize() error {
+func (r *intervalRotator) initialize(log Logger, rotateOnStartup bool, filename string) {
 	r.clock = realClock{}
 
 	switch r.interval {
@@ -93,7 +96,41 @@ func (r *intervalRotator) initialize() error {
 			return lastInterval != currentInterval
 		}
 	}
-	return nil
+
+	// if rotation is not allowed on startup, find the newest rotated file last modification time
+	// or that of the unrotated log file
+	if !rotateOnStartup {
+		logsDir := filepath.Dir(filename)
+		logfiles, err := ioutil.ReadDir(logsDir)
+		if err != nil && log != nil {
+			log.Debugw("Not attempting to find last rotated time, configured logs dir cannot be opened: %v", err)
+			return
+		}
+
+		r.lastRotate = time.Time{}
+		if len(logfiles) == 1 && logfiles[0].Name() == filename {
+			if log != nil {
+				log.Debugw("Setting last rotated time to the last modification time of the log")
+			}
+
+			r.lastRotate = logfiles[0].ModTime()
+			return
+		}
+		basenamePrefix := filepath.Base(filename) + "-"
+		for _, fi := range logfiles {
+			if strings.HasPrefix(fi.Name(), basenamePrefix) {
+				if fi.ModTime().After(r.lastRotate) {
+					r.lastRotate = fi.ModTime()
+				}
+			}
+		}
+
+		if log != nil {
+			log.Debugw("Set last rotated time to", r.lastRotate)
+		}
+	}
+
+	return
 }
 
 func (r *intervalRotator) LogPrefix(filename string, modTime time.Time) string {

libbeat/common/file/interval_rotator_test.go

@@ -25,7 +25,7 @@ import (
 )
 
 func TestSecondRotator(t *testing.T) {
-	a, err := newIntervalRotator(time.Second)
+	a, err := newMockIntervalRotator(time.Second)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -51,7 +51,7 @@ func TestSecondRotator(t *testing.T) {
 }
 
 func TestMinuteRotator(t *testing.T) {
-	a, err := newIntervalRotator(time.Minute)
+	a, err := newMockIntervalRotator(time.Minute)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -77,7 +77,7 @@ func TestMinuteRotator(t *testing.T) {
 }
 
 func TestHourlyRotator(t *testing.T) {
-	a, err := newIntervalRotator(time.Hour)
+	a, err := newMockIntervalRotator(time.Hour)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -103,7 +103,7 @@ func TestHourlyRotator(t *testing.T) {
 }
 
 func TestDailyRotator(t *testing.T) {
-	a, err := newIntervalRotator(24 * time.Hour)
+	a, err := newMockIntervalRotator(24 * time.Hour)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -129,7 +129,7 @@ func TestDailyRotator(t *testing.T) {
 }
 
 func TestWeeklyRotator(t *testing.T) {
-	a, err := newIntervalRotator(7 * 24 * time.Hour)
+	a, err := newMockIntervalRotator(7 * 24 * time.Hour)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -158,7 +158,7 @@ func TestWeeklyRotator(t *testing.T) {
 }
 
 func TestMonthlyRotator(t *testing.T) {
-	a, err := newIntervalRotator(30 * 24 * time.Hour)
+	a, err := newMockIntervalRotator(30 * 24 * time.Hour)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -184,7 +184,7 @@ func TestMonthlyRotator(t *testing.T) {
 }
 
 func TestYearlyRotator(t *testing.T) {
-	a, err := newIntervalRotator(365 * 24 * time.Hour)
+	a, err := newMockIntervalRotator(365 * 24 * time.Hour)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -210,7 +210,7 @@ func TestYearlyRotator(t *testing.T) {
 }
 
 func TestArbitraryIntervalRotator(t *testing.T) {
-	a, err := newIntervalRotator(3 * time.Second)
+	a, err := newMockIntervalRotator(3 * time.Second)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -253,15 +253,15 @@ func TestArbitraryIntervalRotator(t *testing.T) {
 }
 
 func TestIntervalIsTruncatedToSeconds(t *testing.T) {
-	a, err := newIntervalRotator(2345 * time.Millisecond)
+	a, err := newMockIntervalRotator(2345 * time.Millisecond)
 	if err != nil {
 		t.Fatal(err)
 	}
 	assert.Equal(t, 2*time.Second, a.interval)
 }
 
 func TestZeroIntervalIsNil(t *testing.T) {
-	a, err := newIntervalRotator(0)
+	a, err := newMockIntervalRotator(0)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -275,3 +275,7 @@ type testClock struct {
 func (t testClock) Now() time.Time {
 	return t.time
 }
+
+func newMockIntervalRotator(interval time.Duration) (*intervalRotator, error) {
+	return newIntervalRotator(nil, interval, false, "foo")
+}

libbeat/common/file/rotator.go

@@ -166,7 +166,7 @@ func NewFileRotator(filename string, options ...RotatorOption) (*Rotator, error)
 		return nil, errors.Errorf("file rotator permissions mask of %o is invalid", r.permissions)
 	}
 	var err error
-	r.intervalRotator, err = newIntervalRotator(r.interval)
+	r.intervalRotator, err = newIntervalRotator(r.log, r.interval, r.rotateOnStartup, r.filename)
 	if err != nil {
 		return nil, err
 	}