etcdserver: delete member directory when discovery fails

When discovery fails, etcd node falls back to proxy. And in order to
start as a proxy, we need to make sure there are conflicting directories:
'member' and 'proxy' directories cannot be existent together. This deletes
'member' directory only when startEtcd fails (#3827).

etcdserver/server.go

@@ -194,7 +194,7 @@ type EtcdServer struct {
 
 // NewServer creates a new EtcdServer from the supplied configuration. The
 // configuration is considered static for the lifetime of the EtcdServer.
-func NewServer(cfg *ServerConfig) (*EtcdServer, error) {
+func NewServer(cfg *ServerConfig) (srv *EtcdServer, err error) {
 	st := store.New(StoreClusterPrefix, StoreKeysPrefix)
 	var (
 		w  *wal.WAL
@@ -223,12 +223,21 @@ func NewServer(cfg *ServerConfig) (*EtcdServer, error) {
 	}
 
 	haveWAL := wal.Exist(cfg.WALDir())
+	if !haveWAL {
+		defer func() {
+			if err != nil {
+				// cleans up member directory if bootstrap fails (including forming or joining a new cluster)
+				os.RemoveAll(cfg.MemberDir())
+			}
+		}()
+	}
 	ss := snap.New(cfg.SnapDir())
 
 	prt, err := rafthttp.NewRoundTripper(cfg.PeerTLSInfo, cfg.peerDialTimeout())
 	if err != nil {
 		return nil, err
 	}
+
 	var remotes []*Member
 	switch {
 	case !haveWAL && !cfg.NewCluster:
@@ -239,11 +248,12 @@ func NewServer(cfg *ServerConfig) (*EtcdServer, error) {
 		if err != nil {
 			return nil, err
 		}
-		existingCluster, err := GetClusterFromRemotePeers(getRemotePeerURLs(cl, cfg.Name), prt)
-		if err != nil {
+		existingCluster, e := GetClusterFromRemotePeers(getRemotePeerURLs(cl, cfg.Name), prt)
+		if e != nil {
+			err = e
 			return nil, fmt.Errorf("cannot fetch cluster info from peer urls: %v", err)
 		}
-		if err := ValidateClusterAndAssignIDs(cl, existingCluster); err != nil {
+		if err = ValidateClusterAndAssignIDs(cl, existingCluster); err != nil {
 			return nil, fmt.Errorf("error validating peerURLs %s: %v", existingCluster, err)
 		}
 		if !isCompatibleWithCluster(cl, cl.MemberByName(cfg.Name).ID, prt) {
@@ -256,7 +266,7 @@ func NewServer(cfg *ServerConfig) (*EtcdServer, error) {
 		cfg.Print()
 		id, n, s, w = startNode(cfg, cl, nil)
 	case !haveWAL && cfg.NewCluster:
-		if err := cfg.VerifyBootstrap(); err != nil {
+		if err = cfg.VerifyBootstrap(); err != nil {
 			return nil, err
 		}
 		cl, err = newClusterFromURLsMap(cfg.InitialClusterToken, cfg.InitialPeerURLsMap)
@@ -274,8 +284,9 @@ func NewServer(cfg *ServerConfig) (*EtcdServer, error) {
 			if err != nil {
 				return nil, &DiscoveryError{Op: "join", Err: err}
 			}
-			urlsmap, err := types.NewURLsMap(str)
-			if err != nil {
+			urlsmap, e := types.NewURLsMap(str)
+			if e != nil {
+				err = e
 				return nil, err
 			}
 			if checkDuplicateURL(urlsmap) {
@@ -335,7 +346,7 @@ func NewServer(cfg *ServerConfig) (*EtcdServer, error) {
 	sstats.Initialize()
 	lstats := stats.NewLeaderStats(id.String())
 
-	srv := &EtcdServer{
+	srv = &EtcdServer{
 		cfg:       cfg,
 		snapCount: cfg.SnapCount,
 		errorc:    make(chan error, 1),