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/errors_test.go

@@ -0,0 +1,49 @@
+package httputil
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestErrorResponse(t *testing.T) {
+	tests := []struct {
+		name string
+		rw   http.ResponseWriter
+		r    *http.Request
+		e    *Error
+	}{
+		{"good", httptest.NewRecorder(), &http.Request{Method: http.MethodGet}, &Error{Code: http.StatusBadRequest, Message: "missing id token"}},
+		{"good json", httptest.NewRecorder(), &http.Request{Method: http.MethodGet, Header: http.Header{"Accept": []string{"application/json"}}}, &Error{Code: http.StatusBadRequest, Message: "missing id token"}},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ErrorResponse(tt.rw, tt.r, tt.e)
+		})
+	}
+}
+
+func TestError_Error(t *testing.T) {
+
+	tests := []struct {
+		name     string
+		Message  string
+		Code     int
+		CanDebug bool
+		want     string
+	}{
+		{"good", "short and stout", http.StatusTeapot, false, "418 I'm a teapot: short and stout"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			h := Error{
+				Message:  tt.Message,
+				Code:     tt.Code,
+				CanDebug: tt.CanDebug,
+			}
+			if got := h.Error(); got != tt.want {
+				t.Errorf("Error.Error() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}