package consul import ( "fmt" "io" "strconv" "sync" "sync/atomic" "time" "github.com/armon/go-metrics" "github.com/armon/go-metrics/prometheus" "github.com/hashicorp/go-hclog" "github.com/hashicorp/serf/serf" "golang.org/x/time/rate" "github.com/hashicorp/consul/acl" "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/logging" "github.com/hashicorp/consul/tlsutil" "github.com/hashicorp/consul/types" ) var ClientCounters = []prometheus.CounterDefinition{ { Name: []string{"client", "rpc"}, Help: "Increments whenever a Consul agent in client mode makes an RPC request to a Consul server.", }, { Name: []string{"client", "rpc", "exceeded"}, Help: "Increments whenever a Consul agent in client mode makes an RPC request to a Consul server gets rate limited by that agent's limits configuration.", }, { Name: []string{"client", "rpc", "failed"}, Help: "Increments whenever a Consul agent in client mode makes an RPC request to a Consul server and fails.", }, } const ( // 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 *ACLResolver // Connection pool to consul servers connPool *pool.ConnPool // router is responsible for the selection and maintenance of // Consul servers this agent uses for RPC requests router *router.Router // 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 hclog.InterceptLogger // 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 tlsConfigurator *tlsutil.Configurator } // NewClient creates and returns a Client func NewClient(config *Config, deps Deps) (*Client, error) { if err := config.CheckProtocolVersion(); err != nil { return nil, err } if config.DataDir == "" { return nil, fmt.Errorf("Config must provide a DataDir") } if err := config.CheckACL(); err != nil { return nil, err } c := &Client{ config: config, connPool: deps.ConnPool, eventCh: make(chan serf.Event, serfEventBacklog), logger: deps.Logger.NamedIntercept(logging.ConsulClient), shutdownCh: make(chan struct{}), tlsConfigurator: deps.TLSConfigurator, } c.rpcLimiter.Store(rate.NewLimiter(config.RPCRateLimit, config.RPCMaxBurst)) if err := c.initEnterprise(deps); err != nil { c.Shutdown() return nil, err } aclConfig := ACLResolverConfig{ Config: config.ACLResolverSettings, Backend: &clientACLResolverBackend{Client: c}, Logger: c.logger, DisableDuration: aclClientDisabledTTL, CacheConfig: clientACLCacheConfig, ACLConfig: newACLConfig(&partitionInfoNoop{}, c.logger), Tokens: deps.Tokens, } var err error if c.ACLResolver, 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 err := deps.Router.AddArea(types.AreaLAN, c.serf, c.connPool); err != nil { c.Shutdown() return nil, fmt.Errorf("Failed to add LAN area to the RPC router: %w", err) } c.router = deps.Router // 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() return c, nil } // Shutdown is used to shutdown the client func (c *Client) Shutdown() error { c.logger.Info("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() c.ACLResolver.Close() return nil } // Leave is used to prepare for a graceful shutdown. func (c *Client) Leave() error { c.logger.Info("client starting leave") // Leave the LAN pool if c.serf != nil { if err := c.serf.Leave(); err != nil { c.logger.Error("Failed to leave LAN Serf cluster", "error", err) } } return nil } // JoinLAN is used to have Consul 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, entMeta *acl.EnterpriseMeta) (int, error) { // Partitions definitely have to match. if c.config.AgentEnterpriseMeta().PartitionOrDefault() != entMeta.PartitionOrDefault() { return 0, fmt.Errorf("target partition %q must match client agent partition %q", entMeta.PartitionOrDefault(), c.config.AgentEnterpriseMeta().PartitionOrDefault(), ) } return c.serf.Join(addrs, true) } // AgentLocalMember is used to retrieve the LAN member for the local node. func (c *Client) AgentLocalMember() serf.Member { return c.serf.LocalMember() } // LANMembersInAgentPartition returns the LAN members for this agent's // canonical serf pool. For clients this is the only pool that exists. For // servers it's the pool in the default segment and the default partition. func (c *Client) LANMembersInAgentPartition() []serf.Member { return c.serf.Members() } // LANMembers returns the LAN members for one of: // // - the requested partition // - the requested segment // - all segments // // This is limited to segments and partitions that the node is a member of. func (c *Client) LANMembers(filter LANMemberFilter) ([]serf.Member, error) { if err := filter.Validate(); err != nil { return nil, err } // Partitions definitely have to match. if c.config.AgentEnterpriseMeta().PartitionOrDefault() != filter.PartitionOrDefault() { return nil, fmt.Errorf("partition %q not found", filter.PartitionOrDefault()) } if !filter.AllSegments && filter.Segment != c.config.Segment { return nil, fmt.Errorf("segment %q not found", filter.Segment) } return c.serf.Members(), nil } // RemoveFailedNode is used to remove a failed node from the cluster. func (c *Client) RemoveFailedNode(node string, prune bool, entMeta *acl.EnterpriseMeta) error { // Partitions definitely have to match. if c.config.AgentEnterpriseMeta().PartitionOrDefault() != entMeta.PartitionOrDefault() { return fmt.Errorf("client agent in partition %q cannot remove node in different partition %q", c.config.AgentEnterpriseMeta().PartitionOrDefault(), entMeta.PartitionOrDefault()) } if !isSerfMember(c.serf, node) { return fmt.Errorf("agent: No node found with name '%s'", node) } if prune { return c.serf.RemoveFailedNodePrune(node) } return c.serf.RemoveFailedNode(node) } // KeyManagerLAN returns the LAN Serf keyring manager func (c *Client) KeyManagerLAN() *serf.KeyManager { return c.serf.KeyManager() } // 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: manager, server := c.router.FindLANRoute() 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.ShortName, server.Addr, method, args, reply) if rpcErr == nil { return nil } // Move off to another server, and see if we can retry. manager.NotifyFailedServer(server) // Use the zero value for RPCInfo if the request doesn't implement RPCInfo info, _ := args.(structs.RPCInfo) if retry := canRetry(info, rpcErr, firstCheck, c.config); !retry { c.logger.Error("RPC failed to server", "method", method, "server", server.Addr, "error", rpcErr, ) metrics.IncrCounterWithLabels([]string{"client", "rpc", "failed"}, 1, []metrics.Label{{Name: "server", Value: server.Name}}) return rpcErr } c.logger.Warn("Retrying RPC to server", "method", method, "server", server.Addr, "error", rpcErr, ) // We can wait a bit and retry! jitter := lib.RandomStagger(c.config.RPCHoldTimeout / structs.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 { manager, server := c.router.FindLANRoute() 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.ShortName, server.Addr, args, in, &reply) if err != nil { manager.NotifyFailedServer(server) return err } defer func() { if err := snap.Close(); err != nil { c.logger.Error("Failed closing snapshot stream", "error", err) } }() // Let the caller peek at the reply. if replyFn != nil { if err := replyFn(&reply); err != nil { return err } } // 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.router.GetLANManager().NumServers() toString := func(v uint64) string { return strconv.FormatUint(v, 10) } stats := map[string]map[string]string{ "consul": { "server": "false", "known_servers": toString(uint64(numServers)), }, "serf_lan": c.serf.Stats(), "runtime": runtimeStats(), } if c.config.ACLsEnabled { stats["consul"]["acl"] = "enabled" } else { stats["consul"]["acl"] = "disabled" } return stats } // GetLANCoordinate returns the coordinate of the node in the LAN gossip // pool. // // - Clients return a single coordinate for the single gossip pool they are // in (default, segment, or partition). // // - Servers return one coordinate for their canonical gossip pool (i.e. // default partition/segment) and one per segment they are also ancillary // members of. // // NOTE: servers do not emit coordinates for partitioned gossip pools they // are ancillary members of. // // NOTE: This assumes coordinates are enabled, so check that before calling. 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 ReloadableConfig) error { c.rpcLimiter.Store(rate.NewLimiter(config.RPCRateLimit, config.RPCMaxBurst)) c.connPool.SetRPCClientTimeout(config.RPCClientTimeout) return nil } func (c *Client) AgentEnterpriseMeta() *acl.EnterpriseMeta { return c.config.AgentEnterpriseMeta() } func (c *Client) agentSegmentName() string { return c.config.Segment }