Always create snapshot when cluster version changes

When downgrading or offline migration, etcd read the maximum version from the WAL files, so as to ensure the operation is allowed. It also reads the verson from `ClusterVersionSet` request, so we should create a snapshot when cluster version chanages, so as not to block the downgrade or migration operations. Signed-off-by: Benjamin Wang <[email protected]>
etcd-io · Jan 7, 2025 · 7f7ebde · 7f7ebde
1 parent d17821f
commit 7f7ebde
Show file tree

Hide file tree

Showing 4 changed files with 8 additions and 14 deletions.
diff --git a/server/etcdserver/apply/apply.go b/server/etcdserver/apply/apply.go
@@ -415,7 +415,6 @@ func (a *applierMembership) ClusterVersionSet(r *membershippb.ClusterVersionSetR
 	prevVersion := a.cluster.Version()
 	newVersion := semver.Must(semver.NewVersion(r.Ver))
 	a.cluster.SetVersion(newVersion, api.UpdateCapability, shouldApplyV3)
-	// Force snapshot after cluster version downgrade.
 	if prevVersion != nil && newVersion.LessThan(*prevVersion) {
 		lg := a.lg
 		if lg != nil {
@@ -424,8 +423,9 @@ func (a *applierMembership) ClusterVersionSet(r *membershippb.ClusterVersionSetR
 				zap.String("new-cluster-version", newVersion.String()),
 			)
 		}
-		a.snapshotServer.ForceSnapshot()
 	}
+	// Force snapshot when cluster version changes.
+	a.snapshotServer.ForceSnapshot()
 }
 
 func (a *applierMembership) ClusterMemberAttrSet(r *membershippb.ClusterMemberAttrSetRequest, shouldApplyV3 membership.ShouldApplyV3) {

diff --git a/server/etcdserver/bootstrap.go b/server/etcdserver/bootstrap.go
@@ -216,7 +216,7 @@ func bootstrapBackend(cfg config.ServerConfig, haveWAL bool, st v2store.Store, s
 			return nil, err
 		}
 	}
-	cfg.Logger.Debug("restore consistentIndex", zap.Uint64("index", ci.ConsistentIndex()))
+	cfg.Logger.Info("restore consistentIndex", zap.Uint64("index", ci.ConsistentIndex()))
 
 	// TODO(serathius): Implement schema setup in fresh storage
 	var snapshot *raftpb.Snapshot

diff --git a/tests/e2e/etcd_mix_versions_test.go b/tests/e2e/etcd_mix_versions_test.go
@@ -148,8 +148,8 @@ func mixVersionsSnapshotTestByMockPartition(t *testing.T, cfg *e2e.EtcdProcessCl
 	err = toPartitionedMember.Stop()
 	require.NoError(t, err)
 
-	t.Log("Writing 20 keys to the cluster (more than SnapshotCount entries to trigger at least a snapshot)")
-	writeKVs(t, epc.Etcdctl(), 0, 20)
+	t.Log("Writing 30 keys to the cluster (more than SnapshotCount entries to trigger at least a snapshot)")
+	writeKVs(t, epc.Etcdctl(), 0, 30)
 
 	t.Log("Verify logs to check leader has saved snapshot")
 	leaderEPC := epc.Procs[epc.WaitLeader(t)]

diff --git a/tests/e2e/utl_migrate_test.go b/tests/e2e/utl_migrate_test.go
@@ -90,16 +90,10 @@ func TestEtctlutlMigrate(t *testing.T) {
 			expectStorageVersion: &version.V3_6,
 		},
 		{
-			name:                 "Downgrade v3.6 to v3.5 should fail until it's implemented",
+			name:                 "Downgrade v3.6 to v3.5 should work",
 			targetVersion:        "3.5",
-			expectLogsSubString:  "cannot downgrade storage, WAL contains newer entries",
-			expectStorageVersion: &version.V3_6,
-		},
-		{
-			name:                "Downgrade v3.6 to v3.5 with force should work",
-			targetVersion:       "3.5",
-			force:               true,
-			expectLogsSubString: "forcefully cleared storage version",
+			expectLogsSubString:  "updated storage version",
+			expectStorageVersion: nil, // 3.5 doesn't have the field `storageVersion`, so it returns nil.
 		},
 		{
 			name:                 "Upgrade v3.6 to v3.7 with force should work",