keyring state store operations (#13016)

Implement the basic upsert, list, and delete operations for
`RootKeyMeta` needed by the Keyring RPCs.

This changeset also implements two convenience methods
`RootKeyMetaByID` and `GetActiveRootKeyMeta` which are useful for
testing but also will be needed to implement the rest of the RPCs.

nomad/state/state_store.go

@@ -6627,14 +6627,92 @@ func (s *StateStore) SecureVariablesQuotas(ws memdb.WatchSet) (memdb.ResultItera
 	return iter, nil
 }
 
+// UpsertRootKeyMeta saves root key meta or updates it in-place.
 func (s *StateStore) UpsertRootKeyMeta(index uint64, rootKeyMeta *structs.RootKeyMeta) error {
-	return nil
+	txn := s.db.WriteTxn(index)
+	defer txn.Abort()
+
+	// get any existing key for updating
+	raw, err := txn.First(TableRootKeyMeta, indexID, rootKeyMeta.KeyID)
+	if err != nil {
+		return fmt.Errorf("root key metadata lookup failed: %v", err)
+	}
+
+	isRotation := false
+
+	if raw != nil {
+		existing := raw.(*structs.RootKeyMeta)
+		rootKeyMeta.CreateIndex = existing.CreateIndex
+		rootKeyMeta.CreateTime = existing.CreateTime
+		isRotation = !existing.Active && rootKeyMeta.Active
+	} else {
+		rootKeyMeta.CreateIndex = index
+		rootKeyMeta.CreateTime = time.Now()
+		isRotation = rootKeyMeta.Active
+	}
+	rootKeyMeta.ModifyIndex = index
+
+	// if the upsert is for a newly-active key, we need to set all the
+	// other keys as inactive in the same transaction.
+	if isRotation {
+		iter, err := txn.Get(TableRootKeyMeta, indexID)
+		if err != nil {
+			return err
+		}
+		for {
+			raw := iter.Next()
+			if raw == nil {
+				break
+			}
+			key := raw.(*structs.RootKeyMeta)
+			if key.Active {
+				key.Active = false
+				key.ModifyIndex = index
+				if err := txn.Insert(TableRootKeyMeta, key); err != nil {
+					return err
+				}
+			}
+		}
+	}
+
+	if err := txn.Insert(TableRootKeyMeta, rootKeyMeta); err != nil {
+		return err
+	}
+
+	// update the indexes table
+	if err := txn.Insert("index", &IndexEntry{TableRootKeyMeta, index}); err != nil {
+		return fmt.Errorf("index update failed: %v", err)
+	}
+	return txn.Commit()
 }
 
+// DeleteRootKeyMeta deletes a single root key, or returns an error if
+// it doesn't exist.
 func (s *StateStore) DeleteRootKeyMeta(index uint64, keyID string) error {
-	return nil
+	txn := s.db.WriteTxn(index)
+	defer txn.Abort()
+
+	// find the old key
+	existing, err := txn.First(TableRootKeyMeta, indexID, keyID)
+	if err != nil {
+		return fmt.Errorf("root key metadata lookup failed: %v", err)
+	}
+	if existing == nil {
+		return fmt.Errorf("root key metadata not found")
+	}
+	if err := txn.Delete(TableRootKeyMeta, existing); err != nil {
+		return fmt.Errorf("root key metadata delete failed: %v", err)
+	}
+
+	// update the indexes table
+	if err := txn.Insert("index", &IndexEntry{TableRootKeyMeta, index}); err != nil {
+		return fmt.Errorf("index update failed: %v", err)
+	}
+
+	return txn.Commit()
 }
 
+// RootKeyMetas returns an iterator over all root key metadata
 func (s *StateStore) RootKeyMetas(ws memdb.WatchSet) (memdb.ResultIterator, error) {
 	txn := s.db.ReadTxn()
 
@@ -6646,3 +6724,42 @@ func (s *StateStore) RootKeyMetas(ws memdb.WatchSet) (memdb.ResultIterator, erro
 	ws.Add(iter.WatchCh())
 	return iter, nil
 }
+
+// RootKeyMetaByID returns a specific root key meta
+func (s *StateStore) RootKeyMetaByID(ws memdb.WatchSet, id string) (*structs.RootKeyMeta, error) {
+	txn := s.db.ReadTxn()
+
+	watchCh, raw, err := txn.FirstWatch(TableRootKeyMeta, indexID, id)
+	if err != nil {
+		return nil, fmt.Errorf("root key metadata lookup failed: %v", err)
+	}
+	ws.Add(watchCh)
+
+	if raw != nil {
+		return raw.(*structs.RootKeyMeta), nil
+	}
+	return nil, nil
+}
+
+// GetActiveRootKeyMeta returns the metadata for the currently active root key
+func (s *StateStore) GetActiveRootKeyMeta(ws memdb.WatchSet) (*structs.RootKeyMeta, error) {
+	txn := s.db.ReadTxn()
+
+	iter, err := txn.Get(TableRootKeyMeta, indexID)
+	if err != nil {
+		return nil, err
+	}
+	ws.Add(iter.WatchCh())
+
+	for {
+		raw := iter.Next()
+		if raw == nil {
+			break
+		}
+		key := raw.(*structs.RootKeyMeta)
+		if key.Active {
+			return key, nil
+		}
+	}
+	return nil, nil
+}

nomad/state/state_store_test.go

@@ -9852,6 +9852,75 @@ func TestStateStore_UpsertScalingEvent_LimitAndOrder(t *testing.T) {
 	require.Equal(expectedEvents, actualEvents)
 }
 
+func TestStateStore_RootKeyMetaData_CRUD(t *testing.T) {
+	ci.Parallel(t)
+	store := testStateStore(t)
+	index, err := store.LatestIndex()
+	require.NoError(t, err)
+
+	// create 3 default keys, one of which is active
+	keyIDs := []string{}
+	for i := 0; i < 3; i++ {
+		key := structs.NewRootKeyMeta()
+		keyIDs = append(keyIDs, key.KeyID)
+		if i == 0 {
+			key.Active = true
+		}
+		index++
+		require.NoError(t, store.UpsertRootKeyMeta(index, key))
+	}
+
+	// retrieve the active key
+	activeKey, err := store.GetActiveRootKeyMeta(nil)
+	require.NoError(t, err)
+	require.NotNil(t, activeKey)
+
+	// update an inactive key to active and verify the rotation
+	inactiveKey, err := store.RootKeyMetaByID(nil, keyIDs[1])
+	require.NoError(t, err)
+	require.NotNil(t, inactiveKey)
+	oldCreateIndex := inactiveKey.CreateIndex
+	newlyActiveKey := inactiveKey.Copy()
+	newlyActiveKey.Active = true
+	index++
+	require.NoError(t, store.UpsertRootKeyMeta(index, newlyActiveKey))
+
+	iter, err := store.RootKeyMetas(nil)
+	require.NoError(t, err)
+	for {
+		raw := iter.Next()
+		if raw == nil {
+			break
+		}
+		key := raw.(*structs.RootKeyMeta)
+		if key.KeyID == newlyActiveKey.KeyID {
+			require.True(t, key.Active, "expected updated key to be active")
+			require.Equal(t, oldCreateIndex, key.CreateIndex)
+		} else {
+			require.False(t, key.Active, "expected other keys to be inactive")
+		}
+	}
+
+	// delete the active key and verify it's been deleted
+	index++
+	require.NoError(t, store.DeleteRootKeyMeta(index, keyIDs[1]))
+
+	iter, err = store.RootKeyMetas(nil)
+	require.NoError(t, err)
+	var found int
+	for {
+		raw := iter.Next()
+		if raw == nil {
+			break
+		}
+		key := raw.(*structs.RootKeyMeta)
+		require.NotEqual(t, keyIDs[1], key.KeyID)
+		require.False(t, key.Active, "expected remaining keys to be inactive")
+		found++
+	}
+	require.Equal(t, 2, found, "expected only 2 keys remaining")
+}
+
 func TestStateStore_Abandon(t *testing.T) {
 	ci.Parallel(t)
 

nomad/structs/secure_variables.go

@@ -1,6 +1,10 @@
 package structs
 
-import "time"
+import (
+	"time"
+
+	"github.com/hashicorp/nomad/helper/uuid"
+)
 
 // SecureVariable is the metadata envelope for a Secure Variable
 type SecureVariable struct {
@@ -151,6 +155,23 @@ type RootKeyMeta struct {
 	ModifyIndex      uint64
 }
 
+// NewRootKeyMeta returns a new RootKeyMeta with default values
+func NewRootKeyMeta() *RootKeyMeta {
+	return &RootKeyMeta{
+		KeyID:      uuid.Generate(),
+		Algorithm:  EncryptionAlgorithmXChaCha20,
+		CreateTime: time.Now(),
+	}
+}
+
+func (rkm *RootKeyMeta) Copy() *RootKeyMeta {
+	if rkm == nil {
+		return nil
+	}
+	out := *rkm
+	return &out
+}
+
 // EncryptionAlgorithm chooses which algorithm is used for
 // encrypting / decrypting entries with this key
 type EncryptionAlgorithm string