Initial linux agent and api functionality for enrolling servers

agent/internal/logs/spool.go

@@ -0,0 +1,53 @@
+package logs
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"time"
+)
+
+func SaveSpool(dir string, payload []byte) error {
+	if err := os.MkdirAll(dir, 0o700); err != nil {
+		return err
+	}
+	name := fmt.Sprintf("%d.json", time.Now().UnixNano())
+	tmp := filepath.Join(dir, name+".tmp")
+	final := filepath.Join(dir, name)
+	if err := os.WriteFile(tmp, payload, 0o600); err != nil {
+		return err
+	}
+	return os.Rename(tmp, final)
+}
+
+func DrainSpool(dir string, send func([]byte) error) error {
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return err
+	}
+	var files []string
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+		files = append(files, filepath.Join(dir, entry.Name()))
+	}
+	sort.Strings(files)
+	for _, path := range files {
+		data, err := os.ReadFile(path)
+		if err != nil {
+			return err
+		}
+		if err := send(data); err != nil {
+			return err
+		}
+		if err := os.Remove(path); err != nil {
+			return err
+		}
+	}
+	return nil
+}