lint: enable errcheck (#5336)

## Description

Enable errcheck linter throughout the codebase

Closes: #5059

libs/autofile/autofile.go

@@ -79,7 +79,7 @@ func OpenAutoFile(path string) (*AutoFile, error) {
 	signal.Notify(af.hupc, syscall.SIGHUP)
 	go func() {
 		for range af.hupc {
-			af.closeFile()
+			_ = af.closeFile()
 		}
 	}()
 
@@ -103,7 +103,7 @@ func (af *AutoFile) closeFileRoutine() {
 	for {
 		select {
 		case <-af.closeTicker.C:
-			af.closeFile()
+			_ = af.closeFile()
 		case <-af.closeTickerStopc:
 			return
 		}

libs/autofile/autofile_test.go

@@ -17,7 +17,11 @@ import (
 func TestSIGHUP(t *testing.T) {
 	origDir, err := os.Getwd()
 	require.NoError(t, err)
-	defer os.Chdir(origDir)
+	t.Cleanup(func() {
+		if err := os.Chdir(origDir); err != nil {
+			t.Error(err)
+		}
+	})
 
 	// First, create a temporary directory and move into it
 	dir, err := ioutil.TempDir("", "sighup_test")

libs/autofile/cmd/logjack.go

@@ -23,7 +23,10 @@ func parseFlags() (headPath string, chopSize int64, limitSize int64, version boo
 	flagSet.StringVar(&chopSizeStr, "chop", "100M", "Move file if greater than this")
 	flagSet.StringVar(&limitSizeStr, "limit", "10G", "Only keep this much (for each specified file). Remove old files.")
 	flagSet.BoolVar(&version, "version", false, "Version")
-	flagSet.Parse(os.Args[1:])
+	if err := flagSet.Parse(os.Args[1:]); err != nil {
+		fmt.Printf("err parsing flag: %v\n", err)
+		os.Exit(1)
+	}
 	chopSize = parseBytesize(chopSizeStr)
 	limitSize = parseBytesize(limitSizeStr)
 	return

libs/autofile/group.go

@@ -145,7 +145,9 @@ func (g *Group) OnStart() error {
 // NOTE: g.Head must be closed separately using Close.
 func (g *Group) OnStop() {
 	g.ticker.Stop()
-	g.FlushAndSync()
+	if err := g.FlushAndSync(); err != nil {
+		g.Logger.Error("Error flushin to disk", "err", err)
+	}
 }
 
 // Wait blocks until all internal goroutines are finished. Supposed to be
@@ -157,7 +159,9 @@ func (g *Group) Wait() {
 
 // Close closes the head file. The group must be stopped by this moment.
 func (g *Group) Close() {
-	g.FlushAndSync()
+	if err := g.FlushAndSync(); err != nil {
+		g.Logger.Error("Error flushin to disk", "err", err)
+	}
 
 	g.mtx.Lock()
 	_ = g.Head.closeFile()

libs/cli/helper.go

@@ -69,7 +69,7 @@ func RunCaptureWithArgs(cmd Executable, args []string, env map[string]string) (s
 		go func() {
 			var buf bytes.Buffer
 			// io.Copy will end when we call reader.Close() below
-			io.Copy(&buf, reader)
+			io.Copy(&buf, reader) //nolint:errcheck //ignore error
 			stdC <- buf.String()
 		}()
 		return &stdC

libs/log/tmfmt_logger_test.go

@@ -77,6 +77,7 @@ func benchmarkRunnerKitlog(b *testing.B, logger kitlog.Logger, f func(kitlog.Log
 	}
 }
 
+//nolint: errcheck // ignore errors
 var (
 	baseMessage = func(logger kitlog.Logger) { logger.Log("foo_key", "foo_value") }
 	withMessage = func(logger kitlog.Logger) { kitlog.With(logger, "a", "b").Log("d", "f") }

libs/tempfile/tempfile_test.go

@@ -74,16 +74,18 @@ func TestWriteFileAtomicDuplicateFile(t *testing.T) {
 	// Defer here, in case there is a panic in WriteFileAtomic.
 	defer os.Remove(fileToWrite)
 
-	require.Nil(t, err)
-	f.WriteString(testString)
-	WriteFileAtomic(fileToWrite, []byte(expectedString), 0777)
+	require.NoError(t, err)
+	_, err = f.WriteString(testString)
+	require.NoError(t, err)
+	err = WriteFileAtomic(fileToWrite, []byte(expectedString), 0777)
+	require.NoError(t, err)
 	// Check that the first atomic file was untouched
 	firstAtomicFileBytes, err := ioutil.ReadFile(fname)
-	require.Nil(t, err, "Error reading first atomic file")
+	require.NoError(t, err, "Error reading first atomic file")
 	require.Equal(t, []byte(testString), firstAtomicFileBytes, "First atomic file was overwritten")
 	// Check that the resultant file is correct
 	resultantFileBytes, err := ioutil.ReadFile(fileToWrite)
-	require.Nil(t, err, "Error reading resultant file")
+	require.NoError(t, err, "Error reading resultant file")
 	require.Equal(t, []byte(expectedString), resultantFileBytes, "Written file had incorrect bytes")
 
 	// Check that the intermediate write file was deleted
@@ -113,7 +115,8 @@ func TestWriteFileAtomicManyDuplicates(t *testing.T) {
 		fname := "/tmp/" + atomicWriteFilePrefix + fileRand
 		f, err := os.OpenFile(fname, atomicWriteFileFlag, 0777)
 		require.Nil(t, err)
-		f.WriteString(fmt.Sprintf(testString, i))
+		_, err = f.WriteString(fmt.Sprintf(testString, i))
+		require.NoError(t, err)
 		defer os.Remove(fname)
 	}
 
@@ -121,7 +124,8 @@ func TestWriteFileAtomicManyDuplicates(t *testing.T) {
 	// Defer here, in case there is a panic in WriteFileAtomic.
 	defer os.Remove(fileToWrite)
 
-	WriteFileAtomic(fileToWrite, []byte(expectedString), 0777)
+	err := WriteFileAtomic(fileToWrite, []byte(expectedString), 0777)
+	require.NoError(t, err)
 	// Check that all intermittent atomic file were untouched
 	atomicWriteFileRand = defaultSeed
 	for i := 0; i < atomicWriteFileMaxNumConflicts+2; i++ {