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/const.go

@@ -0,0 +1,41 @@
+package metrics // import "github.com/pomerium/pomerium/internal/telemetry/metrics"
+
+import (
+	"go.opencensus.io/plugin/ocgrpc"
+	"go.opencensus.io/stats/view"
+	"go.opencensus.io/tag"
+)
+
+// The following tags are applied to stats recorded by this package.
+var (
+	TagKeyHTTPMethod  tag.Key = tag.MustNewKey("http_method")
+	TagKeyService     tag.Key = tag.MustNewKey("service")
+	TagKeyGRPCService tag.Key = tag.MustNewKey("grpc_service")
+	TagKeyGRPCMethod  tag.Key = tag.MustNewKey("grpc_method")
+	TagKeyHost        tag.Key = tag.MustNewKey("host")
+	TagKeyDestination tag.Key = tag.MustNewKey("destination")
+)
+
+// Default distributions used by views in this package.
+var (
+	DefaulHTTPSizeDistribution = view.Distribution(
+		1, 256, 512, 1024, 2048, 8192, 16384, 32768, 65536, 131072, 262144,
+		524288, 1048576, 2097152, 4194304, 8388608)
+	DefaultHTTPLatencyDistrubtion = view.Distribution(
+		1, 2, 5, 7, 10, 25, 500, 750, 100, 250, 500, 750, 1000, 2500, 5000,
+		7500, 10000, 25000, 50000, 75000, 100000)
+	grpcSizeDistribution = view.Distribution(
+		1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024,
+		2048, 4096, 8192, 16384,
+	)
+	DefaultMillisecondsDistribution = ocgrpc.DefaultMillisecondsDistribution
+)
+
+// DefaultViews are a set of default views to view HTTP and GRPC metrics.
+var (
+	DefaultViews = [][]*view.View{
+		GRPCServerViews,
+		HTTPServerViews,
+		GRPCClientViews,
+		GRPCServerViews}
+)