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/telemetry/metrics/helpers_test.go

@@ -0,0 +1,38 @@
+package metrics // import "github.com/pomerium/pomerium/internal/telemetry/metrics"
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"go.opencensus.io/metric/metricdata"
+)
+
+func testMetricRetrieval(metrics []*metricdata.Metric, t *testing.T, labels []metricdata.LabelValue, value interface{}, name string) {
+	switch value.(type) {
+	case int64:
+	case float64:
+	case uint64:
+	default:
+		t.Errorf("Got an unexpected type for value: %T", value)
+	}
+
+	found := false
+	for _, metric := range metrics {
+		if metric.Descriptor.Name != name {
+			found = true
+			continue
+		}
+		gotLabels := metric.TimeSeries[0].LabelValues
+		gotValue := metric.TimeSeries[0].Points[0].Value
+
+		if diff := cmp.Diff(gotLabels, labels); diff != "" {
+			t.Errorf("Failed to find metric labels:\n%s", diff)
+		}
+		if diff := cmp.Diff(gotValue, value); diff != "" {
+			t.Errorf("Failed to find metric value:\n%s", diff)
+		}
+	}
+	if !found {
+		t.Errorf("Could not find metric %s", name)
+	}
+}