Backport of Fix snapshot creation issue. into release/1.15.x (#18788)

backport of commit fe581326aa

Co-authored-by: Derek Menteer <derek.menteer@hashicorp.com>

agent/consul/fsm/snapshot.go

@@ -13,6 +13,8 @@ import (
 	"github.com/hashicorp/raft"
 )
 
+var cePersister, entPersister persister
+
 var SnapshotSummaries = []prometheus.SummaryDefinition{
 	{
 		Name: []string{"fsm", "persist"},
@@ -38,15 +40,6 @@ type SnapshotHeader struct {
 // persister is a function used to help snapshot the FSM state.
 type persister func(s *snapshot, sink raft.SnapshotSink, encoder *codec.Encoder) error
 
-// persisters is a list of snapshot functions.
-var persisters []persister
-
-// registerPersister adds a new helper. This should be called at package
-// init() time.
-func registerPersister(fn persister) {
-	persisters = append(persisters, fn)
-}
-
 // restorer is a function used to load back a snapshot of the FSM state.
 type restorer func(header *SnapshotHeader, restore *state.Restore, decoder *codec.Decoder) error
 
@@ -80,7 +73,16 @@ func (s *snapshot) Persist(sink raft.SnapshotSink) error {
 	}
 
 	// Run all the persisters to write the FSM state.
-	for _, fn := range persisters {
+	for _, fn := range []persister{
+		// The enterprise version MUST be executed first, otherwise the snapshot will
+		// not properly function during restore due to missing tenancy objects.
+		entPersister,
+		cePersister,
+	} {
+		// Check for nil, since the enterprise version may not exist in CE.
+		if fn == nil {
+			continue
+		}
 		if err := fn(s, sink, encoder); err != nil {
 			sink.Cancel()
 			return err

agent/consul/fsm/snapshot_ce.go

@@ -14,8 +14,7 @@ import (
 )
 
 func init() {
-	registerPersister(persistCE)
+	cePersister = persistCE
-
 	registerRestorer(structs.RegisterRequestType, restoreRegistration)
 	registerRestorer(structs.KVSRequestType, restoreKV)
 	registerRestorer(structs.TombstoneRequestType, restoreTombstone)