fix: run migrations on restored KV database before swapping it (#21868)

Co-authored-by: William Baker <wbaker@gmail.com>

CHANGELOG.md

@@ -11,12 +11,13 @@ Because of the version bump to `go`, the macOS build for this release requires a
 
 ### Bug Fixes
 
-1. [21748](https://github.com/influxdata/influxdb/pull/21748): rename arm rpms with yum-compatible names.
+1. [21748](https://github.com/influxdata/influxdb/pull/21748): Rename arm rpms with yum-compatible names.
 1. [21851](https://github.com/influxdata/influxdb/pull/21851): Upgrade to latest version of `influxdata/cron` so that tasks can be created with interval of `every: 1w`.
 1. [21859](https://github.com/influxdata/influxdb/pull/21859): Avoid rewriting `fields.idx` unnecessarily.
 1. [21860](https://github.com/influxdata/influxdb/pull/21860): Do not close connection twice in DigestWithOptions.
 1. [21866](https://github.com/influxdata/influxdb/pull/21866): Remove incorrect optimization for group-by.
 1. [21867](https://github.com/influxdata/influxdb/pull/21867): Return an error instead of panicking when InfluxQL statement rewrites fail.
+1. [21868](https://github.com/influxdata/influxdb/pull/21868): Migrate restored KV snapshots to latest schema before using them.
 
 ## v2.0.7 [2021-06-04]
 ----------------------

bolt/kv.go

@@ -13,6 +13,8 @@ import (
 
 	"github.com/influxdata/influxdb/v2/kit/tracing"
 	"github.com/influxdata/influxdb/v2/kv"
+	"github.com/influxdata/influxdb/v2/kv/migration"
+	"github.com/influxdata/influxdb/v2/kv/migration/all"
 	"github.com/influxdata/influxdb/v2/pkg/fs"
 	bolt "go.etcd.io/bbolt"
 	"go.uber.org/zap"
@@ -221,6 +223,11 @@ func (s *KVStore) Restore(ctx context.Context, r io.Reader) error {
 			return err
 		}
 
+		// Run the migrations on the restored database prior to swapping it in.
+		if err := s.migrateRestored(ctx); err != nil {
+			return err
+		}
+
 		// Swap and reopen under lock.
 		s.mu.Lock()
 		defer s.mu.Unlock()
@@ -243,6 +250,33 @@ func (s *KVStore) Restore(ctx context.Context, r io.Reader) error {
 	return nil
 }
 
+// migrateRestored opens the database at the temporary path and applies the
+// migrations to it. The database at the temporary path is closed after the
+// migrations are complete. This should be used as part of the restore
+// operation, prior to swapping the restored database with the active database.
+func (s *KVStore) migrateRestored(ctx context.Context) error {
+	restoredClient := NewClient(s.log.With(zap.String("service", "restored bolt")))
+	restoredClient.Path = s.tempPath()
+	if err := restoredClient.Open(ctx); err != nil {
+		return err
+	}
+	defer restoredClient.Close()
+
+	restoredKV := NewKVStore(s.log.With(zap.String("service", "restored kvstore-bolt")), s.tempPath())
+	restoredKV.WithDB(restoredClient.DB())
+
+	migrator, err := migration.NewMigrator(
+		s.log.With(zap.String("service", "bolt restore migrations")),
+		restoredKV,
+		all.Migrations[:]...,
+	)
+	if err != nil {
+		return err
+	}
+
+	return migrator.Up(ctx)
+}
+
 // Tx is a light wrapper around a boltdb transaction. It implements kv.Tx.
 type Tx struct {
 	tx  *bolt.Tx