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_test.go

@@ -0,0 +1,49 @@
+package httputil
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestNewHTTPServer(t *testing.T) {
+	tests := []struct {
+		name string
+		opts *ServerOptions
+		// wantErr bool
+	}{
+		{"localhost:9232", &ServerOptions{Addr: "localhost:9232"}},
+		{"localhost:65536", &ServerOptions{Addr: "localhost:-1"}}, // will fail, but won't err
+		{"empty", &ServerOptions{}},
+		{"empty", nil},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			srv := NewHTTPServer(tt.opts, RedirectHandler())
+
+			defer srv.Close()
+
+			// we cheat a little bit here and use the httptest server to test the client
+			ts := httptest.NewServer(srv.Handler)
+			defer ts.Close()
+			client := ts.Client()
+			client.CheckRedirect = func(req *http.Request, via []*http.Request) error {
+				return http.ErrUseLastResponse
+			}
+			res, err := client.Get(ts.URL)
+			if err != nil {
+				log.Fatal(err)
+			}
+			greeting, err := ioutil.ReadAll(res.Body)
+			res.Body.Close()
+			if err != nil {
+				log.Fatal(err)
+			}
+			fmt.Printf("%s", greeting)
+
+		})
+	}
+}