etcdserver: use roundTripper to request peerURL

It uses roundTripper instead of Transport because roundTripper is
sufficient for its requirements.

etcdserver/cluster_util.go

@@ -29,8 +29,8 @@ import (
 
 // isMemberBootstrapped tries to check if the given member has been bootstrapped
 // in the given cluster.
-func isMemberBootstrapped(cl *cluster, member string, tr *http.Transport) bool {
-	rcl, err := getClusterFromRemotePeers(getRemotePeerURLs(cl, member), time.Second, false, tr)
+func isMemberBootstrapped(cl *cluster, member string, rt http.RoundTripper) bool {
+	rcl, err := getClusterFromRemotePeers(getRemotePeerURLs(cl, member), time.Second, false, rt)
 	if err != nil {
 		return false
 	}
@@ -52,14 +52,14 @@ func isMemberBootstrapped(cl *cluster, member string, tr *http.Transport) bool {
 // response, an error is returned.
 // Each request has a 10-second timeout. Because the upper limit of TTL is 5s,
 // 10 second is enough for building connection and finishing request.
-func GetClusterFromRemotePeers(urls []string, tr *http.Transport) (*cluster, error) {
-	return getClusterFromRemotePeers(urls, 10*time.Second, true, tr)
+func GetClusterFromRemotePeers(urls []string, rt http.RoundTripper) (*cluster, error) {
+	return getClusterFromRemotePeers(urls, 10*time.Second, true, rt)
 }
 
 // If logerr is true, it prints out more error messages.
-func getClusterFromRemotePeers(urls []string, timeout time.Duration, logerr bool, tr *http.Transport) (*cluster, error) {
+func getClusterFromRemotePeers(urls []string, timeout time.Duration, logerr bool, rt http.RoundTripper) (*cluster, error) {
 	cc := &http.Client{
-		Transport: tr,
+		Transport: rt,
 		Timeout:   timeout,
 	}
 	for _, u := range urls {
@@ -114,7 +114,7 @@ func getRemotePeerURLs(cl Cluster, local string) []string {
 // The key of the returned map is the member's ID. The value of the returned map
 // is the semver versions string, including server and cluster.
 // If it fails to get the version of a member, the key will be nil.
-func getVersions(cl Cluster, local types.ID, tr *http.Transport) map[string]*version.Versions {
+func getVersions(cl Cluster, local types.ID, rt http.RoundTripper) map[string]*version.Versions {
 	members := cl.Members()
 	vers := make(map[string]*version.Versions)
 	for _, m := range members {
@@ -126,7 +126,7 @@ func getVersions(cl Cluster, local types.ID, tr *http.Transport) map[string]*ver
 			vers[m.ID.String()] = &version.Versions{Server: version.Version, Cluster: cv}
 			continue
 		}
-		ver, err := getVersion(m, tr)
+		ver, err := getVersion(m, rt)
 		if err != nil {
 			plog.Warningf("cannot get the version of member %s (%v)", m.ID, err)
 			vers[m.ID.String()] = nil
@@ -172,8 +172,8 @@ func decideClusterVersion(vers map[string]*version.Versions) *semver.Version {
 // cluster version in the range of [MinClusterVersion, Version] and no known members has a cluster version
 // out of the range.
 // We set this rule since when the local member joins, another member might be offline.
-func isCompatibleWithCluster(cl Cluster, local types.ID, tr *http.Transport) bool {
-	vers := getVersions(cl, local, tr)
+func isCompatibleWithCluster(cl Cluster, local types.ID, rt http.RoundTripper) bool {
+	vers := getVersions(cl, local, rt)
 	minV := semver.Must(semver.NewVersion(version.MinClusterVersion))
 	maxV := semver.Must(semver.NewVersion(version.Version))
 	maxV = &semver.Version{
@@ -214,9 +214,9 @@ func isCompatibleWithVers(vers map[string]*version.Versions, local types.ID, min
 
 // getVersion returns the Versions of the given member via its
 // peerURLs. Returns the last error if it fails to get the version.
-func getVersion(m *Member, tr *http.Transport) (*version.Versions, error) {
+func getVersion(m *Member, rt http.RoundTripper) (*version.Versions, error) {
 	cc := &http.Client{
-		Transport: tr,
+		Transport: rt,
 	}
 	var (
 		err  error

etcdserver/server.go

@@ -171,8 +171,8 @@ type EtcdServer struct {
 	// consistent index used to hold the offset of current executing entry
 	// It is initialized to 0 before executing any entry.
 	consistIndex consistentIndex
-	// versionTr used to send requests for peer version
-	versionTr *http.Transport
+	// versionRt used to send requests for peer version
+	versionRt http.RoundTripper
 	reqIDGen  *idutil.Generator
 
 	// forceVersionC is used to force the version monitor loop
@@ -216,6 +216,7 @@ func NewServer(cfg *ServerConfig) (*EtcdServer, error) {
 	if err != nil {
 		return nil, err
 	}
+	prt := http.RoundTripper(pt)
 	var remotes []*Member
 	switch {
 	case !haveWAL && !cfg.NewCluster:
@@ -226,14 +227,14 @@ func NewServer(cfg *ServerConfig) (*EtcdServer, error) {
 		if err != nil {
 			return nil, err
 		}
-		existingCluster, err := GetClusterFromRemotePeers(getRemotePeerURLs(cl, cfg.Name), pt)
+		existingCluster, err := GetClusterFromRemotePeers(getRemotePeerURLs(cl, cfg.Name), prt)
 		if err != nil {
 			return nil, fmt.Errorf("cannot fetch cluster info from peer urls: %v", err)
 		}
 		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, pt) {
+		if !isCompatibleWithCluster(cl, cl.MemberByName(cfg.Name).ID, prt) {
 			return nil, fmt.Errorf("incomptible with current running cluster")
 		}
 
@@ -251,7 +252,7 @@ func NewServer(cfg *ServerConfig) (*EtcdServer, error) {
 			return nil, err
 		}
 		m := cl.MemberByName(cfg.Name)
-		if isMemberBootstrapped(cl, cfg.Name, pt) {
+		if isMemberBootstrapped(cl, cfg.Name, prt) {
 			return nil, fmt.Errorf("member %s has already been bootstrapped", m.ID)
 		}
 		if cfg.ShouldDiscover() {
@@ -339,7 +340,7 @@ func NewServer(cfg *ServerConfig) (*EtcdServer, error) {
 		stats:         sstats,
 		lstats:        lstats,
 		SyncTicker:    time.Tick(500 * time.Millisecond),
-		versionTr:     pt,
+		versionRt:     prt,
 		reqIDGen:      idutil.NewGenerator(uint8(id), time.Now()),
 		forceVersionC: make(chan struct{}),
 	}
@@ -1091,7 +1092,7 @@ func (s *EtcdServer) monitorVersions() {
 			continue
 		}
 
-		v := decideClusterVersion(getVersions(s.cluster, s.id, s.versionTr))
+		v := decideClusterVersion(getVersions(s.cluster, s.id, s.versionRt))
 		if v != nil {
 			// only keep major.minor version for comparasion
 			v = &semver.Version{