persists node seed on each disk to be safe if disk changed (#74)

Signed-off-by: Ashraf Fouda <ashraf.m.fouda@gmail.com>

Author: ashraffouda

pkg/identity/store/file.go

@@ -4,6 +4,7 @@ import (
 	"crypto/ed25519"
 	"encoding/json"
 	"os"
+	"path/filepath"
 
 	"github.com/pkg/errors"
 	"github.com/threefoldtech/zosbase/pkg/versioned"
@@ -39,19 +40,78 @@ func (f *FileStore) Kind() string {
 
 func (f *FileStore) Set(key ed25519.PrivateKey) error {
 	seed := key.Seed()
-	return versioned.WriteFile(f.path, SeedVersion1, seed, 0400)
+	// write to primary location first
+	if err := versioned.WriteFile(f.path, SeedVersion1, seed, 0400); err != nil {
+		return err
+	}
+
+	// also mirror the seed to all mounted disks under /mnt/*/seed.txt
+	mirrors, _ := f.mirrorPaths()
+	for _, p := range mirrors {
+		_ = versioned.WriteFile(p, SeedVersion1, seed, 0400)
+	}
+	return nil
 }
 
 func (f *FileStore) Annihilate() error {
 	return os.Remove(f.path)
 }
 
 func (f *FileStore) Get() (ed25519.PrivateKey, error) {
-	version, data, err := versioned.ReadFile(f.path)
+	key, err := f.readKeyFrom(f.path)
+	if errors.Is(err, ErrKeyDoesNotExist) {
+		// try to recover from any mirrored copies on mounted disks
+		mirrors, _ := f.mirrorPaths()
+		for _, p := range mirrors {
+			if k, merr := f.readKeyFrom(p); merr == nil {
+				// write back to primary location for future boots
+				_ = os.MkdirAll(filepath.Dir(f.path), 0o700)
+				_ = versioned.WriteFile(f.path, SeedVersion1, k.Seed(), 0400)
+				// ensure the seed is present across all mirrors
+				_ = f.ensureMirrors(k.Seed())
+				return k, nil
+			}
+		}
+	}
+	if err == nil {
+		// ensure the seed is present across all mirrors on every successful read
+		_ = f.ensureMirrors(key.Seed())
+	}
+	return key, err
+}
+
+func (f *FileStore) Exists() (bool, error) {
+	if _, err := os.Stat(f.path); os.IsNotExist(err) {
+		return false, nil
+	} else if err != nil {
+		return false, errors.Wrap(err, "failed to check seed file")
+	}
+
+	return true, nil
+}
+
+// ensureMirrors guarantees that the seed file exists on all mirror locations under /mnt/*
+// It is best-effort; failures for individual mirrors are ignored.
+func (f *FileStore) ensureMirrors(seed []byte) error {
+	mirrors, err := f.mirrorPaths()
+	if err != nil {
+		return err
+	}
+	for _, p := range mirrors {
+		if _, statErr := os.Stat(p); os.IsNotExist(statErr) {
+			_ = versioned.WriteFile(p, SeedVersion1, seed, 0400)
+		}
+	}
+	return nil
+}
+
+// readKeyFrom reads and decodes an identity seed from a given path
+// supporting both 1.0.0 (raw seed) and 1.1.0 (mnemonic json) formats.
+func (f *FileStore) readKeyFrom(path string) (ed25519.PrivateKey, error) {
+	version, data, err := versioned.ReadFile(path)
 	if versioned.IsNotVersioned(err) {
-		// this is a compatibility code for seed files
-		// in case it does not have any version information
-		if err := versioned.WriteFile(f.path, SeedVersionLatest, data, 0400); err != nil {
+		// compatibility for old non-versioned seed files
+		if err := versioned.WriteFile(path, SeedVersionLatest, data, 0400); err != nil {
 			return nil, err
 		}
 		version = SeedVersion1
@@ -68,6 +128,7 @@ func (f *FileStore) Get() (ed25519.PrivateKey, error) {
 	if version.EQ(SeedVersion1) {
 		return keyFromSeed(data)
 	}
+
 	// it means we read json data instead of the secret
 	type Seed110Struct struct {
 		Mnemonics string `json:"mnemonic"`
@@ -85,12 +146,20 @@ func (f *FileStore) Get() (ed25519.PrivateKey, error) {
 	return keyFromSeed(seed)
 }
 
-func (f *FileStore) Exists() (bool, error) {
-	if _, err := os.Stat(f.path); os.IsNotExist(err) {
-		return false, nil
-	} else if err != nil {
-		return false, errors.Wrap(err, "failed to check seed file")
+// mirrorPaths lists candidate seed paths under all mounted disks in /mnt/*
+// The path is mirrored at: /mnt/<disk>/seed.txt (flat, no original directories)
+func (f *FileStore) mirrorPaths() ([]string, error) {
+	entries, err := os.ReadDir("/mnt")
+	if err != nil {
+		return nil, err
 	}
-
-	return true, nil
+	var paths []string
+	for _, e := range entries {
+		if !e.IsDir() {
+			continue
+		}
+		name := filepath.Base(f.path) // usually "seed.txt"
+		paths = append(paths, filepath.Join("/mnt", e.Name(), name))
+	}
+	return paths, nil
 }