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server.go
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server.go
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// Package server provides HTTP server implementation.
// The server provided in here is opinionated and comes with good defaults.
package server
import (
"context"
"crypto/tls"
"errors"
"fmt"
"log/slog"
"net"
"net/http"
"os"
"os/signal"
"syscall"
"time"
"github.com/komuw/ong/automax"
"github.com/komuw/ong/config"
"github.com/komuw/ong/internal/acme"
"github.com/komuw/ong/internal/finger"
"github.com/komuw/ong/internal/octx"
"github.com/komuw/ong/log"
"github.com/komuw/ong/middleware"
"github.com/komuw/ong/mux"
"golang.org/x/sys/unix" // syscall package is deprecated
)
// Run creates a http server, starts the server on a network address and then calls Serve to handle requests on incoming connections.
//
// It sets up a server with the parameters provided by o.
// If the Opts supplied include a certificate and key, the server will accept https traffic and also automatically handle http->https redirect.
// Likewise, if the Opts include an acmeEmail address, the server will accept https traffic and automatically handle http->https redirect.
//
// The server shuts down cleanly after receiving any termination signal.
func Run(h http.Handler, o config.Opts) error {
_ = automax.SetCpu()
_ = automax.SetMem()
{ // Add handlers.
if m, ok := h.(mux.Muxer); ok {
{ // 1. Add ACME route handler.
// Support for acme certificate manager needs to be added in three places:
// (a) In http middlewares.
// (b) In http server.
// (c) In http multiplexer.
const acmeChallengeURI = "/.well-known/acme-challenge/:token"
if err := m.Unwrap().AddRoute(
mux.NewRoute(
acmeChallengeURI,
mux.MethodAll,
acme.Handler(m),
),
); err != nil {
return fmt.Errorf("ong/server: unable to add ACME handler: %w", err)
}
}
{ // 2. Add pprof route handler.
var (
errJ error
profHandler = pprofHandler(o)
)
basicAuth, errA := middleware.BasicAuth(
profHandler,
string(o.SecretKey),
string(o.SecretKey),
)
if errA != nil {
errJ = errors.Join(errJ, errA)
}
if errB := m.Unwrap().AddRoute(
mux.NewRoute(
"/debug/pprof",
mux.MethodAll,
basicAuth,
),
); errB != nil {
errJ = errors.Join(errJ, errB)
}
if errC := m.Unwrap().AddRoute(
mux.NewRoute(
"/debug/pprof/:part",
mux.MethodAll,
basicAuth,
),
); errC != nil {
errJ = errors.Join(errJ, errC)
}
if errJ != nil {
return fmt.Errorf("ong/server: unable to add pprof handler: %w", errJ)
}
}
}
}
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
tlsConf, errTc := getTlsConfig(o)
if errTc != nil {
return errTc
}
server := &http.Server{
Addr: o.ServerPort,
TLSConfig: tlsConf,
// 1. https://blog.simon-frey.eu/go-as-in-golang-standard-net-http-config-will-break-your-production
// 2. https://blog.cloudflare.com/exposing-go-on-the-internet/
// 3. https://blog.cloudflare.com/the-complete-guide-to-golang-net-http-timeouts/
// 4. https://github.com/golang/go/issues/27375
Handler: http.MaxBytesHandler(
h,
int64(o.MaxBodyBytes), // limit in bytes.
),
// http.TimeoutHandler does not implement [http.ResponseController] so we no longer use it.
ReadHeaderTimeout: o.ReadHeaderTimeout,
ReadTimeout: o.ReadTimeout,
WriteTimeout: o.WriteTimeout,
IdleTimeout: o.IdleTimeout,
ErrorLog: slog.NewLogLogger(o.Logger.Handler(), o.ServerLogLevel),
BaseContext: func(net.Listener) context.Context { return ctx },
ConnContext: func(ctx context.Context, c net.Conn) context.Context {
tConn, ok := c.(*tls.Conn)
if !ok {
return ctx
}
conn, ok := tConn.NetConn().(*fingerConn)
if !ok {
return ctx
}
fPrint := conn.fingerprint.Load()
if fPrint == nil {
fPrint = &finger.Print{}
conn.fingerprint.CompareAndSwap(nil, fPrint)
}
return context.WithValue(ctx, octx.FingerPrintCtxKey, fPrint)
},
}
sigHandler(server, ctx, cancel, o.Logger, o.DrainTimeout)
err := serve(ctx, server, o)
if !errors.Is(err, http.ErrServerClosed) {
// The docs for http.server.Shutdown() says:
// When Shutdown is called, Serve/ListenAndServe/ListenAndServeTLS immediately return ErrServerClosed.
// Make sure the program doesn't exit and waits instead for Shutdown to return.
//
return err // already wrapped in the `serve` func.
}
return nil
}
func sigHandler(
srv *http.Server,
ctx context.Context,
cancel context.CancelFunc,
logger *slog.Logger,
drainDur time.Duration,
) {
sigs := make(chan os.Signal, 1)
signal.Notify(sigs, unix.SIGTERM, unix.SIGINT, unix.SIGQUIT, unix.SIGHUP)
go func() {
defer cancel()
sigCaught := <-sigs
sl := slog.NewLogLogger(logger.Handler(), log.LevelImmediate)
sl.Println("server got shutdown signal.",
"signal =", fmt.Sprintf("%v.", sigCaught),
"shutdownDuration =", drainDur.String(),
)
{
// If your app is running in kubernetes(k8s), if a pod is deleted;
// (a) it gets deleted from service endpoints.
// (b) it receives a SIGTERM from kubelet.
// (a) & (b) are done concurrently. Thus (b) can occur before (a);
// if that is the case; your app will shutdown while k8s is still sending traffic to it.
// This sleep here, minimizes the duration of that race condition.
// - https://twitter.com/ProgrammerDude/status/1660238268863066114
// - https://twitter.com/thockin/status/1560398974929973248
time.Sleep(drainDur)
}
err := srv.Shutdown(ctx)
if err != nil {
logger.Error("server shutdown error", "error", err)
}
}()
}
func serve(ctx context.Context, srv *http.Server, o config.Opts) error {
{
// HTTP(non-tls) LISTERNER:
redirectSrv := &http.Server{
Addr: fmt.Sprintf("%s%s", o.Host, o.HttpPort),
Handler: srv.Handler,
ReadHeaderTimeout: o.ReadHeaderTimeout,
ReadTimeout: o.ReadTimeout,
WriteTimeout: o.WriteTimeout,
IdleTimeout: o.IdleTimeout,
ErrorLog: slog.NewLogLogger(o.Logger.Handler(), o.ServerLogLevel),
BaseContext: func(net.Listener) context.Context { return ctx },
}
go func() {
redirectSrvCfg := listenerConfig()
redirectSrvListener, errL := redirectSrvCfg.Listen(ctx, "tcp", redirectSrv.Addr)
if errL != nil {
o.Logger.Error("redirect server, unable to create listener", "error", errL)
return
}
slog.NewLogLogger(o.Logger.Handler(), log.LevelImmediate).
Printf("redirect server listening at %s", redirectSrv.Addr)
errRedirectSrv := redirectSrv.Serve(redirectSrvListener)
if errRedirectSrv != nil {
o.Logger.Error("unable to start redirect server", "error", errRedirectSrv)
}
}()
}
{
// HTTPS(tls) LISTERNER:
cfg := listenerConfig()
cl, err := cfg.Listen(ctx, o.Network, o.ServerAddress)
if err != nil {
return err
}
l := &fingerListener{cl}
slog.NewLogLogger(o.Logger.Handler(), log.LevelImmediate).Printf("https server listening at %s", o.ServerAddress)
if errS := srv.ServeTLS(
l,
// use empty cert & key. they will be picked from `srv.TLSConfig`
"",
"",
); errS != nil {
return errS
}
}
return nil
}
// listenerConfig creates a net listener config that reuses address and port.
// This is essential in order to be able to carry out zero-downtime deploys.
func listenerConfig() *net.ListenConfig {
return &net.ListenConfig{
Control: func(network, address string, conn syscall.RawConn) error {
return conn.Control(func(descriptor uintptr) {
_ = unix.SetsockoptInt(
int(descriptor),
unix.SOL_SOCKET,
// go vet will complain if we used syscall.SO_REUSEPORT, even though it would work.
// this is because Go considers syscall pkg to be frozen. The same goes for syscall.SetsockoptInt
// so we use x/sys/unix
// see: https://github.com/golang/go/issues/26771
unix.SO_REUSEPORT,
1,
)
_ = unix.SetsockoptInt(
int(descriptor),
unix.SOL_SOCKET,
unix.SO_REUSEADDR,
1,
)
})
},
}
}