open-consul/agent/pool/pool.go

660 lines
17 KiB
Go

package pool
import (
"container/list"
"context"
"crypto/tls"
"fmt"
"log"
"net"
"sync"
"sync/atomic"
"time"
msgpackrpc "github.com/hashicorp/consul-net-rpc/net-rpc-msgpackrpc"
"github.com/hashicorp/consul-net-rpc/net/rpc"
"github.com/hashicorp/yamux"
"github.com/hashicorp/consul/agent/structs"
"github.com/hashicorp/consul/lib"
"github.com/hashicorp/consul/tlsutil"
)
const DefaultDialTimeout = 10 * time.Second
// muxSession is used to provide an interface for a stream multiplexer.
type muxSession interface {
Open() (net.Conn, error)
Close() error
}
// streamClient is used to wrap a stream with an RPC client
type StreamClient struct {
stream net.Conn
codec rpc.ClientCodec
}
func (sc *StreamClient) Close() {
sc.stream.Close()
sc.codec.Close()
}
// Conn is a pooled connection to a Consul server
type Conn struct {
refCount int32
shouldClose int32
nodeName string
addr net.Addr
session muxSession
lastUsed time.Time
pool *ConnPool
clients *list.List
clientLock sync.Mutex
}
func (c *Conn) Close() error {
return c.session.Close()
}
// getClient is used to get a cached or new client
func (c *Conn) getClient() (*StreamClient, error) {
// Check for cached client
c.clientLock.Lock()
front := c.clients.Front()
if front != nil {
c.clients.Remove(front)
}
c.clientLock.Unlock()
if front != nil {
return front.Value.(*StreamClient), nil
}
// Open a new session
stream, err := c.session.Open()
if err != nil {
return nil, err
}
// Create the RPC client
codec := msgpackrpc.NewCodecFromHandle(true, true, stream, structs.MsgpackHandle)
// Return a new stream client
sc := &StreamClient{
stream: stream,
codec: codec,
}
return sc, nil
}
// returnStream is used when done with a stream
// to allow re-use by a future RPC
func (c *Conn) returnClient(client *StreamClient) {
didSave := false
c.clientLock.Lock()
if c.clients.Len() < c.pool.MaxStreams && atomic.LoadInt32(&c.shouldClose) == 0 {
c.clients.PushFront(client)
didSave = true
// If this is a Yamux stream, shrink the internal buffers so that
// we can GC the idle memory
if ys, ok := client.stream.(*yamux.Stream); ok {
ys.Shrink()
}
}
c.clientLock.Unlock()
if !didSave {
client.Close()
}
}
// markForUse does all the bookkeeping required to ready a connection for use.
func (c *Conn) markForUse() {
c.lastUsed = time.Now()
atomic.AddInt32(&c.refCount, 1)
}
// ConnPool is used to maintain a connection pool to other Consul
// servers. This is used to reduce the latency of RPC requests between
// servers. It is only used to pool connections in the rpcConsul mode.
// Raft connections are pooled separately. Maintain at most one
// connection per host, for up to MaxTime. When MaxTime connection
// reaping is disabled. MaxStreams is used to control the number of idle
// streams allowed. If TLS settings are provided outgoing connections
// use TLS.
type ConnPool struct {
// SrcAddr is the source address for outgoing connections.
SrcAddr *net.TCPAddr
// Logger passed to yamux
// TODO: consider refactoring to accept a full yamux.Config instead of a logger
Logger *log.Logger
// The maximum time to keep a connection open
MaxTime time.Duration
// The maximum number of open streams to keep
MaxStreams int
// TLSConfigurator
TLSConfigurator *tlsutil.Configurator
// GatewayResolver is a function that returns a suitable random mesh
// gateway address for dialing servers in a given DC. This is only
// needed if wan federation via mesh gateways is enabled.
GatewayResolver func(string) string
// Datacenter is the datacenter of the current agent.
Datacenter string
// Server should be set to true if this connection pool is configured in a
// server instead of a client.
Server bool
sync.Mutex
// pool maps a nodeName+address to a open connection
pool map[string]*Conn
// limiter is used to throttle the number of connect attempts
// to a given address. The first thread will attempt a connection
// and put a channel in here, which all other threads will wait
// on to close.
limiter map[string]chan struct{}
// Used to indicate the pool is shutdown
shutdown bool
shutdownCh chan struct{}
// once initializes the internal data structures and connection
// reaping on first use.
once sync.Once
}
// init configures the initial data structures. It should be called
// by p.once.Do(p.init) in all public methods.
func (p *ConnPool) init() {
p.pool = make(map[string]*Conn)
p.limiter = make(map[string]chan struct{})
p.shutdownCh = make(chan struct{})
if p.MaxTime > 0 {
go p.reap()
}
}
// Shutdown is used to close the connection pool
func (p *ConnPool) Shutdown() error {
p.once.Do(p.init)
p.Lock()
defer p.Unlock()
for _, conn := range p.pool {
conn.Close()
}
p.pool = make(map[string]*Conn)
if p.shutdown {
return nil
}
p.shutdown = true
close(p.shutdownCh)
return nil
}
// acquire will return a pooled connection, if available. Otherwise it will
// wait for an existing connection attempt to finish, if one if in progress,
// and will return that one if it succeeds. If all else fails, it will return a
// newly-created connection and add it to the pool.
func (p *ConnPool) acquire(dc string, nodeName string, addr net.Addr) (*Conn, error) {
if nodeName == "" {
return nil, fmt.Errorf("pool: ConnPool.acquire requires a node name")
}
addrStr := addr.String()
poolKey := nodeName + ":" + addrStr
// Check to see if there's a pooled connection available. This is up
// here since it should the vastly more common case than the rest
// of the code here.
p.Lock()
c := p.pool[poolKey]
if c != nil {
c.markForUse()
p.Unlock()
return c, nil
}
// If not (while we are still locked), set up the throttling structure
// for this address, which will make everyone else wait until our
// attempt is done.
var wait chan struct{}
var ok bool
if wait, ok = p.limiter[addrStr]; !ok {
wait = make(chan struct{})
p.limiter[addrStr] = wait
}
isLeadThread := !ok
p.Unlock()
// If we are the lead thread, make the new connection and then wake
// everybody else up to see if we got it.
if isLeadThread {
c, err := p.getNewConn(dc, nodeName, addr)
p.Lock()
delete(p.limiter, addrStr)
close(wait)
if err != nil {
p.Unlock()
return nil, err
}
p.pool[poolKey] = c
p.Unlock()
return c, nil
}
// Otherwise, wait for the lead thread to attempt the connection
// and use what's in the pool at that point.
select {
case <-p.shutdownCh:
return nil, fmt.Errorf("rpc error: shutdown")
case <-wait:
}
// See if the lead thread was able to get us a connection.
p.Lock()
if c := p.pool[poolKey]; c != nil {
c.markForUse()
p.Unlock()
return c, nil
}
p.Unlock()
return nil, fmt.Errorf("rpc error: lead thread didn't get connection")
}
// HalfCloser is an interface that exposes a TCP half-close without exposing
// the underlying TLS or raw TCP connection.
type HalfCloser interface {
CloseWrite() error
}
// DialTimeout is used to establish a raw connection to the given server, with
// given connection timeout. It also writes RPCTLS as the first byte.
func (p *ConnPool) DialTimeout(
dc string,
nodeName string,
addr net.Addr,
actualRPCType RPCType,
) (net.Conn, HalfCloser, error) {
p.once.Do(p.init)
if p.Server &&
p.GatewayResolver != nil &&
p.TLSConfigurator != nil &&
dc != p.Datacenter {
// NOTE: TLS is required on this branch.
nextProto := actualRPCType.ALPNString()
if nextProto == "" {
return nil, nil, fmt.Errorf("rpc type %d cannot be routed through a mesh gateway", actualRPCType)
}
return DialRPCViaMeshGateway(
context.Background(),
dc,
nodeName,
p.SrcAddr,
p.TLSConfigurator.OutgoingALPNRPCWrapper(),
nextProto,
p.Server,
p.GatewayResolver,
)
}
return p.dial(dc, addr, actualRPCType, RPCTLS)
}
func (p *ConnPool) dial(
dc string,
addr net.Addr,
actualRPCType RPCType,
tlsRPCType RPCType,
) (net.Conn, HalfCloser, error) {
// Try to dial the conn
d := &net.Dialer{LocalAddr: p.SrcAddr, Timeout: DefaultDialTimeout}
conn, err := d.Dial("tcp", addr.String())
if err != nil {
return nil, nil, err
}
var hc HalfCloser
if tcp, ok := conn.(*net.TCPConn); ok {
tcp.SetKeepAlive(true)
tcp.SetNoDelay(true)
// Expose TCPConn CloseWrite method on HalfCloser
hc = tcp
}
// Check if TLS is enabled
if p.TLSConfigurator.UseTLS(dc) {
wrapper := p.TLSConfigurator.OutgoingRPCWrapper()
// Switch the connection into TLS mode
if _, err := conn.Write([]byte{byte(tlsRPCType)}); err != nil {
conn.Close()
return nil, nil, err
}
// Wrap the connection in a TLS client
tlsConn, err := wrapper(dc, conn)
if err != nil {
conn.Close()
return nil, nil, err
}
conn = tlsConn
// If this is a tls.Conn, expose HalfCloser to caller
if tlsConn, ok := conn.(*tls.Conn); ok {
hc = tlsConn
}
}
// Send the type-byte for the protocol if one is required.
//
// When using insecure TLS there is no inner type-byte as these connections
// aren't wrapped like the standard TLS ones are.
if tlsRPCType != RPCTLSInsecure {
if _, err := conn.Write([]byte{byte(actualRPCType)}); err != nil {
conn.Close()
return nil, nil, err
}
}
return conn, hc, nil
}
// DialRPCViaMeshGateway dials the destination node and sets up the connection
// to be the correct RPC type using ALPN. This currently is exclusively used to
// dial other servers in foreign datacenters via mesh gateways.
func DialRPCViaMeshGateway(
ctx context.Context,
dc string, // (metadata.Server).Datacenter
nodeName string, // (metadata.Server).ShortName
srcAddr *net.TCPAddr,
alpnWrapper tlsutil.ALPNWrapper,
nextProto string,
dialingFromServer bool,
gatewayResolver func(string) string,
) (net.Conn, HalfCloser, error) {
if !dialingFromServer {
return nil, nil, fmt.Errorf("must dial via mesh gateways from a server agent")
} else if gatewayResolver == nil {
return nil, nil, fmt.Errorf("gatewayResolver is nil")
} else if alpnWrapper == nil {
return nil, nil, fmt.Errorf("cannot dial via a mesh gateway when outgoing TLS is disabled")
}
gwAddr := gatewayResolver(dc)
if gwAddr == "" {
return nil, nil, structs.ErrDCNotAvailable
}
dialer := &net.Dialer{LocalAddr: srcAddr, Timeout: DefaultDialTimeout}
rawConn, err := dialer.DialContext(ctx, "tcp", gwAddr)
if err != nil {
return nil, nil, err
}
if nextProto != ALPN_RPCGRPC {
// agent/grpc/client.go:dial() handles this in another way for gRPC
if tcp, ok := rawConn.(*net.TCPConn); ok {
_ = tcp.SetKeepAlive(true)
_ = tcp.SetNoDelay(true)
}
}
// NOTE: now we wrap the connection in a TLS client.
tlsConn, err := alpnWrapper(dc, nodeName, nextProto, rawConn)
if err != nil {
return nil, nil, err
}
var conn net.Conn = tlsConn
var hc HalfCloser
if tlsConn, ok := conn.(*tls.Conn); ok {
// Expose *tls.Conn CloseWrite method on HalfCloser
hc = tlsConn
}
return conn, hc, nil
}
// getNewConn is used to return a new connection
func (p *ConnPool) getNewConn(dc string, nodeName string, addr net.Addr) (*Conn, error) {
if nodeName == "" {
return nil, fmt.Errorf("pool: ConnPool.getNewConn requires a node name")
}
// Get a new, raw connection and write the Consul multiplex byte to set the mode
conn, _, err := p.DialTimeout(dc, nodeName, addr, RPCMultiplexV2)
if err != nil {
return nil, err
}
conf := yamux.DefaultConfig()
// override the default because LogOutput conflicts with Logger.
conf.LogOutput = nil
conf.Logger = p.Logger
// Create a multiplexed session
session, err := yamux.Client(conn, conf)
if err != nil {
conn.Close()
return nil, fmt.Errorf("Failed to create yamux client: %w", err)
}
// Wrap the connection
c := &Conn{
refCount: 1,
nodeName: nodeName,
addr: addr,
session: session,
clients: list.New(),
lastUsed: time.Now(),
pool: p,
}
return c, nil
}
// clearConn is used to clear any cached connection, potentially in response to an error
func (p *ConnPool) clearConn(conn *Conn) {
if conn.nodeName == "" {
panic("pool: ConnPool.acquire requires a node name")
}
// Ensure returned streams are closed
atomic.StoreInt32(&conn.shouldClose, 1)
// Clear from the cache
addrStr := conn.addr.String()
poolKey := conn.nodeName + ":" + addrStr
p.Lock()
if c, ok := p.pool[poolKey]; ok && c == conn {
delete(p.pool, poolKey)
}
p.Unlock()
// Close down immediately if idle
if refCount := atomic.LoadInt32(&conn.refCount); refCount == 0 {
conn.Close()
}
}
// releaseConn is invoked when we are done with a conn to reduce the ref count
func (p *ConnPool) releaseConn(conn *Conn) {
refCount := atomic.AddInt32(&conn.refCount, -1)
if refCount == 0 && atomic.LoadInt32(&conn.shouldClose) == 1 {
conn.Close()
}
}
// getClient is used to get a usable client for an address
func (p *ConnPool) getClient(dc string, nodeName string, addr net.Addr) (*Conn, *StreamClient, error) {
retries := 0
START:
// Try to get a conn first
conn, err := p.acquire(dc, nodeName, addr)
if err != nil {
return nil, nil, fmt.Errorf("failed to get conn: %w", err)
}
// Get a client
client, err := conn.getClient()
if err != nil {
p.clearConn(conn)
p.releaseConn(conn)
// Try to redial, possible that the TCP session closed due to timeout
if retries == 0 {
retries++
goto START
}
return nil, nil, fmt.Errorf("failed to start stream: %w", err)
}
return conn, client, nil
}
// RPC is used to make an RPC call to a remote host
func (p *ConnPool) RPC(
dc string,
nodeName string,
addr net.Addr,
method string,
args interface{},
reply interface{},
) error {
if nodeName == "" {
return fmt.Errorf("pool: ConnPool.RPC requires a node name")
}
// TODO (autoconf) probably will want to have a way to invoke the
// secure or insecure variant depending on whether its an ongoing
// or first time config request. For now though this is fine until
// those ongoing requests are implemented.
if method == "AutoEncrypt.Sign" || method == "AutoConfig.InitialConfiguration" {
return p.rpcInsecure(dc, addr, method, args, reply)
} else {
return p.rpc(dc, nodeName, addr, method, args, reply)
}
}
// rpcInsecure is used to make an RPC call to a remote host.
// It doesn't actually use any of the pooling, it is here so that it is
// transparent for the consumer. The pool cannot be used because
// AutoEncrypt.Sign is a one-off call and it doesn't make sense to pool that
// connection if it is not being reused.
func (p *ConnPool) rpcInsecure(dc string, addr net.Addr, method string, args interface{}, reply interface{}) error {
if dc != p.Datacenter {
return fmt.Errorf("insecure dialing prohibited between datacenters")
}
var codec rpc.ClientCodec
conn, _, err := p.dial(dc, addr, 0, RPCTLSInsecure)
if err != nil {
return fmt.Errorf("rpcinsecure error establishing connection: %w", err)
}
codec = msgpackrpc.NewCodecFromHandle(true, true, conn, structs.MsgpackHandle)
// Make the RPC call
err = msgpackrpc.CallWithCodec(codec, method, args, reply)
if err != nil {
return fmt.Errorf("rpcinsecure error making call: %w", err)
}
return nil
}
func (p *ConnPool) rpc(dc string, nodeName string, addr net.Addr, method string, args interface{}, reply interface{}) error {
p.once.Do(p.init)
// Get a usable client
conn, sc, err := p.getClient(dc, nodeName, addr)
if err != nil {
return fmt.Errorf("rpc error getting client: %w", err)
}
// Make the RPC call
err = msgpackrpc.CallWithCodec(sc.codec, method, args, reply)
if err != nil {
sc.Close()
// See the comment in leader_test.go TestLeader_ChangeServerID
// about how we found this. The tldr is that if we see this
// error, we know this connection is toast, so we should clear
// it and make a new one on the next attempt.
if lib.IsErrEOF(err) {
p.clearConn(conn)
}
p.releaseConn(conn)
return fmt.Errorf("rpc error making call: %w", err)
}
// Done with the connection
conn.returnClient(sc)
p.releaseConn(conn)
return nil
}
// Ping sends a Status.Ping message to the specified server and
// returns true if healthy, false if an error occurred
func (p *ConnPool) Ping(dc string, nodeName string, addr net.Addr) (bool, error) {
var out struct{}
err := p.RPC(dc, nodeName, addr, "Status.Ping", struct{}{}, &out)
return err == nil, err
}
// Reap is used to close conns open over maxTime
func (p *ConnPool) reap() {
for {
// Sleep for a while
select {
case <-p.shutdownCh:
return
case <-time.After(time.Second):
}
// Reap all old conns
p.Lock()
var removed []string
now := time.Now()
for host, conn := range p.pool {
// Skip recently used connections
if now.Sub(conn.lastUsed) < p.MaxTime {
continue
}
// Skip connections with active streams
if atomic.LoadInt32(&conn.refCount) > 0 {
continue
}
// Close the conn
conn.Close()
// Remove from pool
removed = append(removed, host)
}
for _, host := range removed {
delete(p.pool, host)
}
p.Unlock()
}
}