Merge pull request containerd#2926 from yankay/fix-tail-rotate-log

Fix the nerdctl stop printing after rotating the json log file

cmd/nerdctl/container_logs_test.go

@@ -24,6 +24,7 @@ import (
 	"time"
 
 	"github.com/containerd/nerdctl/v2/pkg/testutil"
+	"gotest.tools/v3/assert"
 )
 
 func TestLogs(t *testing.T) {
@@ -206,3 +207,30 @@ func TestLogsWithForegroundContainers(t *testing.T) {
 		}(t)
 	}
 }
+
+func TestTailFollowRotateLogs(t *testing.T) {
+	t.Parallel()
+	if runtime.GOOS == "windows" {
+		t.Skip("tail log is not supported on Windows")
+	}
+	base := testutil.NewBase(t)
+	containerName := testutil.Identifier(t)
+
+	const sampleJSONLog = `{"log":"A\n","stream":"stdout","time":"2024-04-11T12:01:09.800288974Z"}`
+	const linesPerFile = 100
+
+	defer base.Cmd("rm", "-f", containerName).Run()
+	base.Cmd("run", "-d", "--log-driver", "json-file",
+		"--log-opt", fmt.Sprintf("max-size=%d", len(sampleJSONLog)*linesPerFile),
+		"--log-opt", "max-file=10",
+		"--name", containerName, testutil.CommonImage,
+		"sh", "-euc", "while true; do echo A; done").AssertOK()
+
+	tailLogCmd := base.Cmd("logs", "-f", containerName)
+	tailLogCmd.Timeout = 100 * time.Millisecond
+	tailLogs := strings.Split(strings.TrimSpace(tailLogCmd.Run().Combined()), "\n")
+	for _, line := range tailLogs {
+		assert.Equal(t, "A", line)
+	}
+	assert.Equal(t, true, len(tailLogs) > linesPerFile)
+}

pkg/logging/json_logger.go

@@ -17,13 +17,15 @@
 package logging
 
 import (
+	"bufio"
 	"errors"
 	"fmt"
 	"io"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/containerd/containerd/runtime/v2/logging"
@@ -208,25 +210,54 @@ func viewLogsJSONFileThroughTailExec(lvopts LogViewOptions, jsonLogFilePath stri
 	}
 
 	if lvopts.Follow {
-		args = append(args, "-f")
+		// using the `-F` to follow the file name instead of descriptor and retry if inaccessible
+		args = append(args, "-F")
 	}
 	args = append(args, jsonLogFilePath)
 	cmd := exec.Command("tail", args...)
-	cmd.Stderr = os.Stderr
-	r, err := cmd.StdoutPipe()
+
+	cmdStdout, err := cmd.StdoutPipe()
+	if err != nil {
+		return err
+	}
+
+	cmdStderr, err := cmd.StderrPipe()
 	if err != nil {
 		return err
 	}
+
 	if err := cmd.Start(); err != nil {
 		return err
 	}
 
+	// filter the unwanted error message of the tail
+	go filterTailStderr(cmdStderr)
+
 	// Setup killing goroutine:
 	go func() {
 		<-stopChannel
 		log.L.Debugf("killing tail logs process with PID: %d", cmd.Process.Pid)
 		cmd.Process.Kill()
 	}()
 
-	return jsonfile.Decode(stdout, stderr, r, lvopts.Timestamps, lvopts.Since, lvopts.Until, 0)
+	return jsonfile.Decode(stdout, stderr, cmdStdout, lvopts.Timestamps, lvopts.Since, lvopts.Until, 0)
+}
+
+func filterTailStderr(reader io.Reader) error {
+	scanner := bufio.NewScanner(reader)
+	for scanner.Scan() {
+		line := scanner.Text()
+		if strings.HasSuffix(line, "has appeared;  following new file") ||
+			strings.HasSuffix(line, "has become inaccessible: No such file or directory") ||
+			strings.HasSuffix(line, "has been replaced;  following new file") ||
+			strings.HasSuffix(line, ": No such file or directory") {
+			continue
+		}
+		fmt.Fprintln(os.Stderr, line)
+	}
+
+	if err := scanner.Err(); err != nil {
+		return err
+	}
+	return nil
 }