package consul import ( "fmt" "io" "log" "os" "strconv" "sync" "sync/atomic" "time" "github.com/armon/go-metrics" "github.com/hashicorp/consul/agent/pool" "github.com/hashicorp/consul/agent/router" "github.com/hashicorp/consul/agent/structs" "github.com/hashicorp/consul/lib" "github.com/hashicorp/consul/tlsutil" "github.com/hashicorp/serf/serf" "golang.org/x/time/rate" ) const ( // clientRPCConnMaxIdle controls how long we keep an idle connection // open to a server. 127s was chosen as the first prime above 120s // (arbitrarily chose to use a prime) with the intent of reusing // connections who are used by once-a-minute cron(8) jobs *and* who // use a 60s jitter window (e.g. in vixie cron job execution can // drift by up to 59s per job, or 119s for a once-a-minute cron job). clientRPCConnMaxIdle = 127 * time.Second // clientMaxStreams controls how many idle streams we keep // open to a server clientMaxStreams = 32 // serfEventBacklog is the maximum number of unprocessed Serf Events // that will be held in queue before new serf events block. A // blocking serf event queue is a bad thing. serfEventBacklog = 256 // serfEventBacklogWarning is the threshold at which point log // warnings will be emitted indicating a problem when processing serf // events. serfEventBacklogWarning = 200 ) // Client is Consul client which uses RPC to communicate with the // services for service discovery, health checking, and DC forwarding. type Client struct { config *Config // acls is used to resolve tokens to effective policies acls *ACLResolver // DEPRECATED (ACL-Legacy-Compat) - Only needed while we support both // useNewACLs is a flag to indicate whether we are using the new ACL system useNewACLs int32 // Connection pool to consul servers connPool *pool.ConnPool // routers is responsible for the selection and maintenance of // Consul servers this agent uses for RPC requests routers *router.Manager // rpcLimiter is used to rate limit the total number of RPCs initiated // from an agent. rpcLimiter atomic.Value // eventCh is used to receive events from the // serf cluster in the datacenter eventCh chan serf.Event // Logger uses the provided LogOutput logger *log.Logger // serf is the Serf cluster maintained inside the DC // which contains all the DC nodes serf *serf.Serf shutdown bool shutdownCh chan struct{} shutdownLock sync.Mutex // embedded struct to hold all the enterprise specific data EnterpriseClient } // NewClient is used to construct a new Consul client from the configuration, // potentially returning an error. // NewClient only used to help setting up a client for testing. Normal code // exercises NewClientLogger. func NewClient(config *Config) (*Client, error) { c, err := tlsutil.NewConfigurator(config.ToTLSUtilConfig(), nil) if err != nil { return nil, err } return NewClientLogger(config, nil, c) } func NewClientLogger(config *Config, logger *log.Logger, tlsConfigurator *tlsutil.Configurator) (*Client, error) { // Check the protocol version if err := config.CheckProtocolVersion(); err != nil { return nil, err } // Check for a data directory! if config.DataDir == "" { return nil, fmt.Errorf("Config must provide a DataDir") } // Sanity check the ACLs if err := config.CheckACL(); err != nil { return nil, err } // Ensure we have a log output if config.LogOutput == nil { config.LogOutput = os.Stderr } // Create a logger if logger == nil { logger = log.New(config.LogOutput, "", log.LstdFlags) } connPool := &pool.ConnPool{ SrcAddr: config.RPCSrcAddr, LogOutput: config.LogOutput, MaxTime: clientRPCConnMaxIdle, MaxStreams: clientMaxStreams, TLSWrapper: tlsConfigurator.OutgoingRPCWrapper(), ForceTLS: config.VerifyOutgoing, } // Create client c := &Client{ config: config, connPool: connPool, eventCh: make(chan serf.Event, serfEventBacklog), logger: logger, shutdownCh: make(chan struct{}), } c.rpcLimiter.Store(rate.NewLimiter(config.RPCRate, config.RPCMaxBurst)) if err := c.initEnterprise(); err != nil { c.Shutdown() return nil, err } c.useNewACLs = 0 aclConfig := ACLResolverConfig{ Config: config, Delegate: c, Logger: logger, AutoDisable: true, CacheConfig: clientACLCacheConfig, Sentinel: nil, } var err error if c.acls, err = NewACLResolver(&aclConfig); err != nil { c.Shutdown() return nil, fmt.Errorf("Failed to create ACL resolver: %v", err) } // Initialize the LAN Serf c.serf, err = c.setupSerf(config.SerfLANConfig, c.eventCh, serfLANSnapshot) if err != nil { c.Shutdown() return nil, fmt.Errorf("Failed to start lan serf: %v", err) } if c.acls.ACLsEnabled() { go c.monitorACLMode() } // Start maintenance task for servers c.routers = router.New(c.logger, c.shutdownCh, c.serf, c.connPool) go c.routers.Start() // Start LAN event handlers after the router is complete since the event // handlers depend on the router and the router depends on Serf. go c.lanEventHandler() if err := c.startEnterprise(); err != nil { c.Shutdown() return nil, err } return c, nil } // Shutdown is used to shutdown the client func (c *Client) Shutdown() error { c.logger.Printf("[INFO] consul: shutting down client") c.shutdownLock.Lock() defer c.shutdownLock.Unlock() if c.shutdown { return nil } c.shutdown = true close(c.shutdownCh) if c.serf != nil { c.serf.Shutdown() } // Close the connection pool c.connPool.Shutdown() return nil } // Leave is used to prepare for a graceful shutdown func (c *Client) Leave() error { c.logger.Printf("[INFO] consul: client starting leave") // Leave the LAN pool if c.serf != nil { if err := c.serf.Leave(); err != nil { c.logger.Printf("[ERR] consul: Failed to leave LAN Serf cluster: %v", err) } } return nil } // JoinLAN is used to have Consul client join the inner-DC pool // The target address should be another node inside the DC // listening on the Serf LAN address func (c *Client) JoinLAN(addrs []string) (int, error) { return c.serf.Join(addrs, true) } // LocalMember is used to return the local node func (c *Client) LocalMember() serf.Member { return c.serf.LocalMember() } // LANMembers is used to return the members of the LAN cluster func (c *Client) LANMembers() []serf.Member { return c.serf.Members() } // LANMembersAllSegments returns members from all segments. func (c *Client) LANMembersAllSegments() ([]serf.Member, error) { return c.serf.Members(), nil } // LANSegmentMembers only returns our own segment's members, because clients // can't be in multiple segments. func (c *Client) LANSegmentMembers(segment string) ([]serf.Member, error) { if segment == c.config.Segment { return c.LANMembers(), nil } return nil, fmt.Errorf("segment %q not found", segment) } // RemoveFailedNode is used to remove a failed node from the cluster func (c *Client) RemoveFailedNode(node string) error { return c.serf.RemoveFailedNode(node) } // KeyManagerLAN returns the LAN Serf keyring manager func (c *Client) KeyManagerLAN() *serf.KeyManager { return c.serf.KeyManager() } // Encrypted determines if gossip is encrypted func (c *Client) Encrypted() bool { return c.serf.EncryptionEnabled() } // RPC is used to forward an RPC call to a consul server, or fail if no servers func (c *Client) RPC(method string, args interface{}, reply interface{}) error { // This is subtle but we start measuring the time on the client side // right at the time of the first request, vs. on the first retry as // is done on the server side inside forward(). This is because the // servers may already be applying the RPCHoldTimeout up there, so by // starting the timer here we won't potentially double up the delay. // TODO (slackpad) Plumb a deadline here with a context. firstCheck := time.Now() TRY: server := c.routers.FindServer() if server == nil { return structs.ErrNoServers } // Enforce the RPC limit. metrics.IncrCounter([]string{"client", "rpc"}, 1) if !c.rpcLimiter.Load().(*rate.Limiter).Allow() { metrics.IncrCounter([]string{"client", "rpc", "exceeded"}, 1) return structs.ErrRPCRateExceeded } // Make the request. rpcErr := c.connPool.RPC(c.config.Datacenter, server.Addr, server.Version, method, server.UseTLS, args, reply) if rpcErr == nil { return nil } // Move off to another server, and see if we can retry. c.logger.Printf("[ERR] consul: %q RPC failed to server %s: %v", method, server.Addr, rpcErr) metrics.IncrCounterWithLabels([]string{"client", "rpc", "failed"}, 1, []metrics.Label{{Name: "server", Value: server.Name}}) c.routers.NotifyFailedServer(server) if retry := canRetry(args, rpcErr); !retry { return rpcErr } // We can wait a bit and retry! if time.Since(firstCheck) < c.config.RPCHoldTimeout { jitter := lib.RandomStagger(c.config.RPCHoldTimeout / jitterFraction) select { case <-time.After(jitter): goto TRY case <-c.shutdownCh: } } return rpcErr } // SnapshotRPC sends the snapshot request to one of the servers, reading from // the streaming input and writing to the streaming output depending on the // operation. func (c *Client) SnapshotRPC(args *structs.SnapshotRequest, in io.Reader, out io.Writer, replyFn structs.SnapshotReplyFn) error { server := c.routers.FindServer() if server == nil { return structs.ErrNoServers } // Enforce the RPC limit. metrics.IncrCounter([]string{"client", "rpc"}, 1) if !c.rpcLimiter.Load().(*rate.Limiter).Allow() { metrics.IncrCounter([]string{"client", "rpc", "exceeded"}, 1) return structs.ErrRPCRateExceeded } // Request the operation. var reply structs.SnapshotResponse snap, err := SnapshotRPC(c.connPool, c.config.Datacenter, server.Addr, server.UseTLS, args, in, &reply) if err != nil { return err } defer func() { if err := snap.Close(); err != nil { c.logger.Printf("[WARN] consul: Failed closing snapshot stream: %v", err) } }() // Let the caller peek at the reply. if replyFn != nil { if err := replyFn(&reply); err != nil { return nil } } // Stream the snapshot. if out != nil { if _, err := io.Copy(out, snap); err != nil { return fmt.Errorf("failed to stream snapshot: %v", err) } } return nil } // Stats is used to return statistics for debugging and insight // for various sub-systems func (c *Client) Stats() map[string]map[string]string { numServers := c.routers.NumServers() toString := func(v uint64) string { return strconv.FormatUint(v, 10) } stats := map[string]map[string]string{ "consul": map[string]string{ "server": "false", "known_servers": toString(uint64(numServers)), }, "serf_lan": c.serf.Stats(), "runtime": runtimeStats(), } if c.ACLsEnabled() { if c.UseLegacyACLs() { stats["consul"]["acl"] = "legacy" } else { stats["consul"]["acl"] = "enabled" } } else { stats["consul"]["acl"] = "disabled" } for outerKey, outerValue := range c.enterpriseStats() { if _, ok := stats[outerKey]; ok { for innerKey, innerValue := range outerValue { stats[outerKey][innerKey] = innerValue } } else { stats[outerKey] = outerValue } } return stats } // GetLANCoordinate returns the network coordinate of the current node, as // maintained by Serf. func (c *Client) GetLANCoordinate() (lib.CoordinateSet, error) { lan, err := c.serf.GetCoordinate() if err != nil { return nil, err } cs := lib.CoordinateSet{c.config.Segment: lan} return cs, nil } // ReloadConfig is used to have the Client do an online reload of // relevant configuration information func (c *Client) ReloadConfig(config *Config) error { c.rpcLimiter.Store(rate.NewLimiter(config.RPCRate, config.RPCMaxBurst)) return nil }