Create log file in append mode (influxdata#5497)

otherpirate · Mar 15, 2019 · abd1edf · abd1edf
1 parent bad226b
commit abd1edf
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Showing 2 changed files with 27 additions and 10 deletions.
diff --git a/logger/logger.go b/logger/logger.go
@@ -50,16 +50,10 @@ func SetupLogging(debug, quiet bool, logfile string) {
 
 	var oFile *os.File
 	if logfile != "" {
-		if _, err := os.Stat(logfile); os.IsNotExist(err) {
-			if oFile, err = os.Create(logfile); err != nil {
-				log.Printf("E! Unable to create %s (%s), using stderr", logfile, err)
-				oFile = os.Stderr
-			}
-		} else {
-			if oFile, err = os.OpenFile(logfile, os.O_APPEND|os.O_WRONLY, os.ModeAppend); err != nil {
-				log.Printf("E! Unable to append to %s (%s), using stderr", logfile, err)
-				oFile = os.Stderr
-			}
+		var err error
+		if oFile, err = os.OpenFile(logfile, os.O_CREATE|os.O_APPEND|os.O_WRONLY, os.ModeAppend|0644); err != nil {
+			log.Printf("E! Unable to open %s (%s), using stderr", logfile, err)
+			oFile = os.Stderr
 		}
 	} else {
 		oFile = os.Stderr

diff --git a/logger/logger_test.go b/logger/logger_test.go
@@ -64,6 +64,29 @@ func TestAddDefaultLogLevel(t *testing.T) {
 	assert.Equal(t, f[19:], []byte("Z I! TEST\n"))
 }
 
+func TestWriteToTruncatedFile(t *testing.T) {
+	tmpfile, err := ioutil.TempFile("", "")
+	assert.NoError(t, err)
+	defer func() { os.Remove(tmpfile.Name()) }()
+
+	SetupLogging(true, false, tmpfile.Name())
+	log.Printf("TEST")
+
+	f, err := ioutil.ReadFile(tmpfile.Name())
+	assert.NoError(t, err)
+	assert.Equal(t, f[19:], []byte("Z I! TEST\n"))
+
+	tmpf, err := os.OpenFile(tmpfile.Name(), os.O_TRUNC, 0644)
+	assert.NoError(t, err)
+	assert.NoError(t, tmpf.Close())
+
+	log.Printf("SHOULD BE FIRST")
+
+	f, err = ioutil.ReadFile(tmpfile.Name())
+	assert.NoError(t, err)
+	assert.Equal(t, f[19:], []byte("Z I! SHOULD BE FIRST\n"))
+}
+
 func BenchmarkTelegrafLogWrite(b *testing.B) {
 	var msg = []byte("test")
 	var buf bytes.Buffer