oss: do a proper check-and-set on the CA roots/config fsm operation

agent/consul/connect_ca_endpoint.go

@@ -78,10 +78,12 @@ func (s *ConnectCA) ConfigurationSet(
 
 	// Exit early if it's a no-op change
 	state := s.srv.fsm.State()
-	_, config, err := state.CAConfig()
+	confIdx, config, err := state.CAConfig()
 	if err != nil {
 		return err
 	}
+
+	// Don't allow users to change the ClusterID.
 	args.Config.ClusterID = config.ClusterID
 	if args.Config.Provider == config.Provider && reflect.DeepEqual(args.Config.Config, config.Config) {
 		return nil
@@ -195,6 +197,7 @@ func (s *ConnectCA) ConfigurationSet(
 
 	args.Op = structs.CAOpSetRootsAndConfig
 	args.Index = idx
+	args.Config.ModifyIndex = confIdx
 	args.Roots = newRoots
 	resp, err := s.srv.raftApply(structs.ConnectCARequestType, args)
 	if err != nil {
@@ -203,6 +206,9 @@ func (s *ConnectCA) ConfigurationSet(
 	if respErr, ok := resp.(error); ok {
 		return respErr
 	}
+	if respOk, ok := resp.(bool); ok && !respOk {
+		return fmt.Errorf("could not atomically update roots and config")
+	}
 
 	// If the config has been committed, update the local provider instance
 	// and call teardown on the old provider
@@ -375,6 +381,20 @@ func (s *ConnectCA) Sign(
 		pem = strings.TrimSpace(pem) + "\n" + p
 	}
 
+	// Append our local CA's intermediate if there is one.
+	inter, err := provider.ActiveIntermediate()
+	if err != nil {
+		return err
+	}
+	root, err := provider.ActiveRoot()
+	if err != nil {
+		return err
+	}
+
+	if inter != root {
+		pem = strings.TrimSpace(pem) + "\n" + inter
+	}
+
 	// TODO(banks): when we implement IssuedCerts table we can use the insert to
 	// that as the raft index to return in response. Right now we can rely on only
 	// the built-in provider being supported and the implementation detail that we

agent/consul/fsm/commands_oss.go

@@ -339,11 +339,14 @@ func (c *FSM) applyConnectCAOperation(buf []byte, index uint64) interface{} {
 		if err != nil {
 			return err
 		}
-
-		if err := c.state.CASetConfig(index+1, req.Config); err != nil {
-			return err
+		if !act {
+			return act
 		}
 
+		act, err = c.state.CACheckAndSetConfig(index+1, req.Config.ModifyIndex, req.Config)
+		if err != nil {
+			return err
+		}
 		return act
 	default:
 		c.logger.Printf("[WARN] consul.fsm: Invalid CA operation '%s'", req.Op)

agent/consul/state/connect_ca.go

@@ -172,7 +172,11 @@ func (s *Store) caSetConfigTxn(idx uint64, tx *memdb.Txn, config *structs.CAConf
 	if prev != nil {
 		existing := prev.(*structs.CAConfiguration)
 		config.CreateIndex = existing.CreateIndex
-		config.ClusterID = existing.ClusterID
+		// Allow the ClusterID to change if it's provided by an internal operation, such
+		// as a primary datacenter being switched to secondary mode.
+		if config.ClusterID == "" {
+			config.ClusterID = existing.ClusterID
+		}
 	} else {
 		config.CreateIndex = idx
 	}