package clientv3
import (
"crypto/tls"
"errors"
"fmt"
"net"
"net/url"
"strings"
"time"
"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
prometheus "github.com/grpc-ecosystem/go-grpc-prometheus"
"golang.org/x/net/context"
"google.golang.org/grpc"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/credentials"
"google.golang.org/grpc/metadata"
)
var (
ErrNoAvailableEndpoints = errors.New("etcdclient: no available endpoints")
)
// Client provides and manages an etcd v3 client session.
type Client struct {
Cluster KV Lease Watcher Auth Maintenanceconn *grpc.ClientConn
cfg Config
creds *credentials.TransportCredentials
balancer *simpleBalancer
retryWrapper retryRpcFunc
ctx context.Context
cancel context.CancelFunc
// Username is a username for authentication
Username string
// Password is a password for authentication
Password string
}
// New creates a new etcdv3 client from a given configuration.
func New(cfg Config) (*Client, error) {
if len(cfg.Endpoints) == 0 {
return nil, ErrNoAvailableEndpoints
}return newClient(&cfg)
}
// NewFromURL creates a new etcdv3 client from a URL.
func NewFromURL(url string) (*Client, error) {
return New(Config{Endpoints: []string{url}})
}
// NewFromConfigFile creates a new etcdv3 client from a configuration file.
func NewFromConfigFile(path string) (*Client, error) {
cfg, err := configFromFile(path)
if err != nil {
return nil, err
}return New(*cfg)
}
// Close shuts down the client‘s etcd connections.
func (c *Client) Close() error {
c.cancel() c.Watcher.Close()return toErr(c.ctx, c.conn.Close())
}
// Ctx is a context for "out of band" messages (e.g., for sending
// "clean up" message when another context is canceled). It is
// canceled on client Close().
func (c *Client) Ctx() context.Context { return c.ctx }
// Endpoints lists the registered endpoints for the client.
func (c *Client) Endpoints() []string { return c.cfg.Endpoints }
// SetEndpoints updates client‘s endpoints.
func (c *Client) SetEndpoints(eps ...string) {
c.cfg.Endpoints = eps
c.balancer.updateAddrs(eps)}
// Sync synchronizes client‘s endpoints with the known endpoints from the etcd membership.
func (c *Client) Sync(ctx context.Context) error {
mresp, err := c.MemberList(ctx)
if err != nil {
return err
}var eps []string
for _, m := range mresp.Members {
eps = append(eps, m.ClientURLs...)
} c.SetEndpoints(eps...)return nil
}
func (c *Client) autoSync() {
if c.cfg.AutoSyncInterval == time.Duration(0) {
return
}for {
select {
case <-c.ctx.Done():
return
case <-time.After(c.cfg.AutoSyncInterval):
ctx, _ := context.WithTimeout(c.ctx, 5*time.Second)
if err := c.Sync(ctx); err != nil && err != c.ctx.Err() {
logger.Println("Auto sync endpoints failed:", err)
} } }}
type authTokenCredential struct {
token string
}
func (cred authTokenCredential) RequireTransportSecurity() bool {
return false
}
func (cred authTokenCredential) GetRequestMetadata(ctx context.Context, s ...string) (map[string]string, error) {
return map[string]string{
"token": cred.token,
}, nil
}
func parseEndpoint(endpoint string) (proto string, host string, scheme string) {
proto = "tcp"
host = endpoint
url, uerr := url.Parse(endpoint)
if uerr != nil || !strings.Contains(endpoint, "://") {
return
}scheme = url.Scheme
// strip scheme:// prefix since grpc dials by host
host = url.Host
switch url.Scheme {
case "http", "https":
case "unix":
proto = "unix"
default:
proto, host = "", ""
}return
}
func (c *Client) processCreds(scheme string) (creds *credentials.TransportCredentials) {
creds = c.creds
switch scheme {
case "unix":
case "http":
creds = nil
case "https":
if creds != nil {
break
}tlsconfig := &tls.Config{}
emptyCreds := credentials.NewTLS(tlsconfig)
creds = &emptyCreds
default:
creds = nil
}return
}
// dialSetupOpts gives the dial opts prior to any authentication
func (c *Client) dialSetupOpts(endpoint string, dopts ...grpc.DialOption) (opts []grpc.DialOption) {
if c.cfg.DialTimeout > 0 {
opts = []grpc.DialOption{grpc.WithTimeout(c.cfg.DialTimeout)}
}opts = append(opts, dopts...)
f := func(host string, t time.Duration) (net.Conn, error) {
proto, host, _ := parseEndpoint(c.balancer.getEndpoint(host))
if proto == "" {
return nil, fmt.Errorf("unknown scheme for %q", host)
}select {
case <-c.ctx.Done():
return nil, c.ctx.Err()
default:
}return net.DialTimeout(proto, host, t)
}opts = append(opts, grpc.WithDialer(f))
creds := c.creds
if _, _, scheme := parseEndpoint(endpoint); len(scheme) != 0 {
creds = c.processCreds(scheme)
}if creds != nil {
opts = append(opts, grpc.WithTransportCredentials(*creds))
} else {
opts = append(opts, grpc.WithInsecure())
}return opts
}
// Dial connects to a single endpoint using the client‘s config.
func (c *Client) Dial(endpoint string) (*grpc.ClientConn, error) {
return c.dial(endpoint)
}
func (c *Client) dial(endpoint string, dopts ...grpc.DialOption) (*grpc.ClientConn, error) {
opts := c.dialSetupOpts(endpoint, dopts...)
host := getHost(endpoint)
if c.Username != "" && c.Password != "" {
// use dial options without dopts to avoid reusing the client balancer
auth, err := newAuthenticator(host, c.dialSetupOpts(endpoint))
if err != nil {
return nil, err
}defer auth.close()
resp, err := auth.authenticate(c.ctx, c.Username, c.Password)
if err != nil {
return nil, err
}opts = append(opts, grpc.WithPerRPCCredentials(authTokenCredential{token: resp.Token}))
}// add metrics options
opts = append(opts, grpc.WithUnaryInterceptor(prometheus.UnaryClientInterceptor))
opts = append(opts, grpc.WithStreamInterceptor(prometheus.StreamClientInterceptor))
conn, err := grpc.Dial(host, opts...)
if err != nil {
return nil, err
}return conn, nil
}
// WithRequireLeader requires client requests to only succeed
// when the cluster has a leader.
func WithRequireLeader(ctx context.Context) context.Context {
md := metadata.Pairs(rpctypes.MetadataRequireLeaderKey, rpctypes.MetadataHasLeader)
return metadata.NewContext(ctx, md)
}
func newClient(cfg *Config) (*Client, error) {
if cfg == nil {
cfg = &Config{}
}var creds *credentials.TransportCredentials
if cfg.TLS != nil {
c := credentials.NewTLS(cfg.TLS)
creds = &c
}// use a temporary skeleton client to bootstrap first connection
ctx, cancel := context.WithCancel(context.TODO())
client := &Client{
conn: nil,
cfg: *cfg,
creds: creds,
ctx: ctx,
cancel: cancel,
}if cfg.Username != "" && cfg.Password != "" {
client.Username = cfg.Username
client.Password = cfg.Password
}client.balancer = newSimpleBalancer(cfg.Endpoints)
conn, err := client.dial(cfg.Endpoints[0], grpc.WithBalancer(client.balancer))
if err != nil {
return nil, err
}client.conn = conn
client.retryWrapper = client.newRetryWrapper()
// wait for a connection
if cfg.DialTimeout > 0 {
hasConn := false
waitc := time.After(cfg.DialTimeout)
select {
case <-client.balancer.readyc:
hasConn = true
case <-ctx.Done():
case <-waitc:
}if !hasConn {
client.cancel() conn.Close()return nil, grpc.ErrClientConnTimeout
} }client.Cluster = NewCluster(client)
client.KV = NewKV(client)
client.Lease = NewLease(client)
client.Watcher = NewWatcher(client)
client.Auth = NewAuth(client)
client.Maintenance = NewMaintenance(client)
go client.autoSync()
return client, nil
}
// ActiveConnection returns the current in-use connection
func (c *Client) ActiveConnection() *grpc.ClientConn { return c.conn }
// isHaltErr returns true if the given error and context indicate no forward
// progress can be made, even after reconnecting.
func isHaltErr(ctx context.Context, err error) bool {
if ctx != nil && ctx.Err() != nil {
return true
}if err == nil {
return false
}code := grpc.Code(err)
// Unavailable codes mean the system will be right back.
// (e.g., can‘t connect, lost leader)
// Treat Internal codes as if something failed, leaving the
// system in an inconsistent state, but retrying could make progress.
// (e.g., failed in middle of send, corrupted frame)
// TODO: are permanent Internal errors possible from grpc?
return code != codes.Unavailable && code != codes.Internal
}
func toErr(ctx context.Context, err error) error {
if err == nil {
return nil
}err = rpctypes.Error(err)
if _, ok := err.(rpctypes.EtcdError); ok {
return err
}code := grpc.Code(err)
switch code {
case codes.DeadlineExceeded:
fallthrough
case codes.Canceled:
if ctx.Err() != nil {
err = ctx.Err()
}case codes.Unavailable:
err = ErrNoAvailableEndpoints
case codes.FailedPrecondition:
err = grpc.ErrClientConnClosing
}return err
}
原文：http://www.cnblogs.com/zhangboyu/p/7452660.html