Simplify admin publishing pipeline

backend/internal/admin/logging.go

@@ -0,0 +1,139 @@
+package admin
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+)
+
+type rotatingLogWriter struct {
+	path       string
+	maxBytes   int64
+	maxBackups int
+	file       *os.File
+	size       int64
+	mu         sync.Mutex
+}
+
+func ConfigureLogging(cfg Config) (io.Closer, error) {
+	if cfg.LogFile == "" {
+		return nil, nil
+	}
+	writer, err := newRotatingLogWriter(cfg.LogFile, cfg.LogMaxBytes, cfg.LogMaxBackups)
+	if err != nil {
+		return nil, err
+	}
+	multi := io.MultiWriter(os.Stdout, writer)
+	log.SetOutput(multi)
+	log.SetFlags(log.LstdFlags | log.Lmicroseconds | log.LUTC)
+	return writer, nil
+}
+
+func newRotatingLogWriter(path string, maxBytes int64, maxBackups int) (*rotatingLogWriter, error) {
+	if maxBytes <= 0 {
+		maxBytes = 10 * 1024 * 1024
+	}
+	if maxBackups <= 0 {
+		maxBackups = 5
+	}
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return nil, fmt.Errorf("create log dir: %w", err)
+	}
+	file, err := os.OpenFile(path, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0o644)
+	if err != nil {
+		return nil, fmt.Errorf("open log file: %w", err)
+	}
+	info, err := file.Stat()
+	if err != nil {
+		file.Close()
+		return nil, fmt.Errorf("stat log file: %w", err)
+	}
+	return &rotatingLogWriter{
+		path:       path,
+		maxBytes:   maxBytes,
+		maxBackups: maxBackups,
+		file:       file,
+		size:       info.Size(),
+	}, nil
+}
+
+func (w *rotatingLogWriter) Write(p []byte) (int, error) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	if w.size+int64(len(p)) > w.maxBytes {
+		if err := w.rotateLocked(); err != nil {
+			return 0, err
+		}
+	}
+	n, err := w.file.Write(p)
+	w.size += int64(n)
+	return n, err
+}
+
+func (w *rotatingLogWriter) Close() error {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	if w.file == nil {
+		return nil
+	}
+	err := w.file.Close()
+	w.file = nil
+	return err
+}
+
+func (w *rotatingLogWriter) rotateLocked() error {
+	if w.file != nil {
+		if err := w.file.Close(); err != nil {
+			return err
+		}
+	}
+	stamp := time.Now().UTC().Format("20060102T150405")
+	rotated := fmt.Sprintf("%s.%s", w.path, stamp)
+	if err := os.Rename(w.path, rotated); err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("rotate log: %w", err)
+	}
+	if err := w.pruneLocked(); err != nil {
+		return err
+	}
+	file, err := os.OpenFile(w.path, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0o644)
+	if err != nil {
+		return fmt.Errorf("open rotated log file: %w", err)
+	}
+	w.file = file
+	w.size = 0
+	return nil
+}
+
+func (w *rotatingLogWriter) pruneLocked() error {
+	pattern := w.path + ".*"
+	matches, err := filepath.Glob(pattern)
+	if err != nil {
+		return fmt.Errorf("list rotated logs: %w", err)
+	}
+	if len(matches) <= w.maxBackups {
+		return nil
+	}
+	sortStrings(matches)
+	for _, path := range matches[:len(matches)-w.maxBackups] {
+		if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
+			return fmt.Errorf("remove old log %s: %w", path, err)
+		}
+	}
+	return nil
+}
+
+func sortStrings(values []string) {
+	for i := 1; i < len(values); i++ {
+		value := values[i]
+		j := i - 1
+		for ; j >= 0 && values[j] > value; j-- {
+			values[j+1] = values[j]
+		}
+		values[j+1] = value
+	}
+}