telemetry: add tracing

- telemetry/tace: add traces throughout code
- telemetry/metrics: nest metrics and trace under telemetry
- telemetry/tace: add service name span to HTTPMetricsHandler.
- telemetry/metrics: removed chain dependency middleware_tests.
- telemetry/metrics: wrap and encapsulate variatic view registration.
- telemetry/tace: add jaeger support for tracing.
- cmd/pomerium: move `parseOptions` to internal/config.
- cmd/pomerium: offload server handling to httputil and sub pkgs.
- httputil: standardize creation/shutdown of http listeners.
- httputil: prefer curve X25519 to P256 when negotiating TLS.
- fileutil: use standardized Getw

Signed-off-by: Bobby DeSimone <bobbydesimone@gmail.com>

internal/httputil/http.go

@@ -0,0 +1,76 @@
+package httputil // import "github.com/pomerium/pomerium/internal/httputil"
+
+import (
+	"context"
+	"fmt"
+	stdlog "log"
+	"net/http"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"github.com/pomerium/pomerium/internal/log"
+	"github.com/pomerium/pomerium/internal/urlutil"
+)
+
+// NewHTTPServer starts a http server given a set of options and a handler.
+//
+// It is the caller's responsibility to Close() or Shutdown() the returned
+// server.
+func NewHTTPServer(opt *ServerOptions, h http.Handler) *http.Server {
+	if opt == nil {
+		opt = defaultHTTPServerOptions
+	} else {
+		opt.applyHTTPDefaults()
+	}
+	sublogger := log.With().Str("addr", opt.Addr).Logger()
+	srv := http.Server{
+		Addr:              opt.Addr,
+		ReadHeaderTimeout: opt.ReadHeaderTimeout,
+		ReadTimeout:       opt.ReadTimeout,
+		WriteTimeout:      opt.WriteTimeout,
+		IdleTimeout:       opt.IdleTimeout,
+		Handler:           h,
+		ErrorLog:          stdlog.New(&log.StdLogWrapper{Logger: &sublogger}, "", 0),
+	}
+
+	go func() {
+		if err := srv.ListenAndServe(); err != http.ErrServerClosed {
+			log.Error().Str("addr", opt.Addr).Err(err).Msg("internal/httputil: unexpected shutdown")
+		}
+	}()
+	return &srv
+}
+
+func RedirectHandler() http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Connection", "close")
+		url := fmt.Sprintf("https://%s%s", urlutil.StripPort(r.Host), r.URL.String())
+		http.Redirect(w, r, url, http.StatusMovedPermanently)
+	})
+}
+
+// Shutdown attempts to shut down the server when a os interrupt or sigterm
+// signal are received without interrupting any
+// active connections. Shutdown works by first closing all open
+// listeners, then closing all idle connections, and then waiting
+// indefinitely for connections to return to idle and then shut down.
+// If the provided context expires before the shutdown is complete,
+// Shutdown returns the context's error, otherwise it returns any
+// error returned from closing the Server's underlying Listener(s).
+//
+// When Shutdown is called, Serve, ListenAndServe, and
+// ListenAndServeTLS immediately return ErrServerClosed.
+func Shutdown(srv *http.Server) {
+	sigint := make(chan os.Signal, 1)
+	signal.Notify(sigint, os.Interrupt)
+	signal.Notify(sigint, syscall.SIGTERM)
+	rec := <-sigint
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+	log.Info().Str("signal", rec.String()).Msg("internal/httputil: shutting down servers")
+	if err := srv.Shutdown(ctx); err != nil {
+		log.Error().Err(err).Msg("internal/httputil: shutdown failed")
+	}
+}