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rpc_server.go
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rpc_server.go
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package server
import (
"errors"
"fmt"
"net"
"net/http"
"runtime/debug"
"strings"
"time"
"github.com/NYTimes/logrotate"
"github.com/go-kit/kit/metrics"
"github.com/go-kit/kit/metrics/provider"
"github.com/gorilla/mux"
"github.com/sirupsen/logrus"
"golang.org/x/net/context"
"google.golang.org/grpc"
"google.golang.org/grpc/metadata"
)
// RPCServer is an experimental server that serves a gRPC server on one
// port and the same endpoints via JSON on another port.
type RPCServer struct {
// tracks if the Register function is already called or not
registered bool
cfg *Config
// exit chan for graceful shutdown
exit chan chan error
// server for handling RPC requests
srvr *grpc.Server
// mux for routing HTTP requests
mux Router
// tracks active requests
monitor *ActivityMonitor
mets provider.Provider
panicCounter metrics.Counter
svc RPCService
}
// NewRPCServer will instantiate a new experimental RPCServer with the given config.
func NewRPCServer(cfg *Config) *RPCServer {
if cfg == nil {
cfg = &Config{}
}
mx := NewRouter(cfg)
if cfg.NotFoundHandler != nil {
mx.SetNotFoundHandler(cfg.NotFoundHandler)
}
mets := newMetricsProvider(cfg)
return &RPCServer{
cfg: cfg,
srvr: grpc.NewServer(),
mux: mx,
exit: make(chan chan error),
monitor: NewActivityMonitor(),
mets: mets,
panicCounter: mets.NewCounter("panic"),
}
}
// Register will attempt to register the given RPCService with the server.
// If any other types are passed, Register will panic.
func (r *RPCServer) Register(svc Service) error {
// check multiple register call error
if r.registered {
return ErrMultiRegister
}
// set registered to true because we called it
r.registered = true
rpcsvc, ok := svc.(RPCService)
if !ok {
Log.Fatalf("invalid service type for rpc server: %T", svc)
}
r.svc = rpcsvc
// register RPC
desc, grpcSvc := rpcsvc.Service()
r.srvr.RegisterService(desc, grpcSvc)
// register endpoints
for _, mthd := range desc.Methods {
registerRPCMetrics(mthd.MethodName, r.mets)
}
// register HTTP
// loop through json endpoints and register them
prefix := svc.Prefix()
// quick fix for backwards compatibility
prefix = strings.TrimRight(prefix, "/")
// register all context endpoints with our wrapper
for path, epMethods := range rpcsvc.ContextEndpoints() {
for method, ep := range epMethods {
// set the function handle and register it to metrics
r.mux.Handle(method, prefix+path, ContextToHTTP(rpcsvc.ContextMiddleware(ep)))
}
}
// register all JSON context endpoints with our wrapper
for path, epMethods := range rpcsvc.JSONEndpoints() {
for method, ep := range epMethods {
// set the function handle and register it to metrics
r.mux.Handle(method, prefix+path, ContextToHTTP(rpcsvc.ContextMiddleware(
JSONContextToHTTP(rpcsvc.JSONMiddleware(ep)),
)))
}
}
RegisterProfiler(r.cfg, r.mux)
return nil
}
// Start start the RPC server.
func (r *RPCServer) Start() error {
// setup RPC
registerRPCAccessLogger(r.cfg)
rl, err := net.Listen("tcp", fmt.Sprintf(":%d", r.cfg.RPCPort))
if err != nil {
return err
}
go func() {
if err := r.srvr.Serve(rl); err != nil {
Log.Error("encountered an error while serving RPC listener: ", err)
}
}()
Log.Infof("RPC listening on %s", rl.Addr().String())
// setup HTTP
healthHandler := RegisterHealthHandler(r.cfg, r.monitor, r.mux)
r.cfg.HealthCheckPath = healthHandler.Path()
wrappedHandler, err := NewAccessLogMiddleware(r.cfg.RPCAccessLog, r)
if err != nil {
Log.Fatalf("unable to create http access log: %s", err)
}
srv := httpServer(wrappedHandler)
var hl net.Listener
hl, err = net.Listen("tcp", fmt.Sprintf(":%d", r.cfg.HTTPPort))
if err != nil {
return err
}
go func() {
if err := srv.Serve(hl); err != nil {
Log.Error("encountered an error while serving listener: ", err)
}
}()
Log.Infof("HTTP listening on %s", hl.Addr().String())
// join the LB
go func() {
exit := <-r.exit
if err := healthHandler.Stop(); err != nil {
Log.Warn("health check Stop returned with error: ", err)
}
r.srvr.Stop()
exit <- hl.Close()
}()
return nil
}
// Stop will signal the RPC server to stop and block until it does.
func (r *RPCServer) Stop() error {
ch := make(chan error)
r.exit <- ch
return <-ch
}
// ServeHTTP is RPCServer's hook for metrics and safely executing each request.
func (r *RPCServer) ServeHTTP(w http.ResponseWriter, req *http.Request) {
AddIPToContext(req)
// only count non-LB requests
if req.URL.Path != r.cfg.HealthCheckPath {
r.monitor.CountRequest()
defer r.monitor.UncountRequest()
}
r.safelyExecuteHTTPRequest(w, req)
}
// executeRequestSafely will prevent a panic in a request from bringing the server down.
func (r *RPCServer) safelyExecuteHTTPRequest(w http.ResponseWriter, req *http.Request) {
defer func() {
if x := recover(); x != nil {
// register a panic'd request with our metrics
r.panicCounter.Add(1)
// log the panic for all the details later
LogWithFields(req).Errorf("rpc server recovered from an HTTP panic\n%v: %v", x, string(debug.Stack()))
// give the users our deepest regrets
w.WriteHeader(http.StatusInternalServerError)
if _, err := w.Write(UnexpectedServerError); err != nil {
LogWithFields(req).Warn("unable to write response: ", err)
}
}
}()
// lookup metric name if we can
registeredPath := req.URL.Path
if muxr, ok := r.mux.(*GorillaRouter); ok {
registeredPath = "__404__"
var match mux.RouteMatch
if muxr.mux.Match(req, &match) {
if tmpl, err := match.Route.GetPathTemplate(); err == nil {
registeredPath = tmpl
}
}
}
TimedAndCounted(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
if req.Body != nil {
defer func() {
if err := req.Body.Close(); err != nil {
Log.Warn("unable to close request body: ", err)
}
}()
}
r.svc.Middleware(r.mux).ServeHTTP(w, req)
}), registeredPath, req.Method, r.mets).ServeHTTP(w, req)
}
// LogRPCWithFields will feed any request context into a logrus Entry.
func LogRPCWithFields(ctx context.Context, log *logrus.Logger) *logrus.Entry {
md, ok := metadata.FromIncomingContext(ctx)
if !ok {
return logrus.NewEntry(log)
}
return log.WithFields(MetadataToFields(md))
}
// MetadataToFields will accept all values from a metadata.MD and
// create logrus.Fields with the same set.
func MetadataToFields(md metadata.MD) logrus.Fields {
f := logrus.Fields{}
for k, v := range md {
f[k] = v
}
return f
}
// MonitorRPCRequest should be deferred by any RPC method that would like to have
// metrics and access logging, participate in graceful shutdowns and safely recover from panics.
func MonitorRPCRequest() func(ctx context.Context, methodName string, err *error) {
start := time.Now()
return func(ctx context.Context, methodName string, err *error) {
m := rpcEndpointMetrics["rpc."+methodName]
x := recover()
if x != nil {
// log the panic for all the details later
Log.Warningf("rpc server recovered from a panic\n%v: %v", x, string(debug.Stack()))
// give the users our deepest regrets
tmp := errors.New(string(UnexpectedServerError))
err = &tmp
}
if m == nil {
Log.Errorf("unable to monitor rpc request. unknown method name: %s", methodName)
return
}
if x != nil {
// register a panic'd request with our metrics
m.PanicCounter.Add(1)
}
if *err == nil {
m.SuccessCounter.Add(1)
} else {
m.ErrorCounter.Add(1)
}
m.Timer.Observe(time.Since(start).Seconds())
if rpcAccessLog != nil {
LogRPCWithFields(ctx, rpcAccessLog).WithFields(logrus.Fields{
"name": methodName,
"duration": time.Since(start),
"error": err,
}).Info("access")
}
}
}
var rpcEndpointMetrics = map[string]*rpcMetrics{}
type rpcMetrics struct {
Timer metrics.Histogram
SuccessCounter metrics.Counter
ErrorCounter metrics.Counter
PanicCounter metrics.Counter
}
func registerRPCMetrics(name string, mets provider.Provider) {
name = "rpc." + name
rpcEndpointMetrics[name] = &rpcMetrics{
Timer: mets.NewHistogram(name+".DURATION", 50),
SuccessCounter: mets.NewCounter(name + ".SUCCESS"),
ErrorCounter: mets.NewCounter(name + ".ERROR"),
PanicCounter: mets.NewCounter(name + ".PANIC"),
}
}
// access logger
var rpcAccessLog *logrus.Logger
func registerRPCAccessLogger(cfg *Config) {
// gRPC doesn't have a hook à la http.Handler-middleware
// so some of this duplicates logic from config.NewAccessLogMiddleware
if cfg.RPCAccessLog == nil {
return
}
lf, err := logrotate.NewFile(*cfg.RPCAccessLog)
if err != nil {
Log.Fatalf("unable to access rpc access log file: %s", err)
}
rpcAccessLog = logrus.New()
rpcAccessLog.Out = lf
}