Adding OpenTracing to Lager

trace_lager.go

func FromContext(context.Context) Logger {}

func FromSpan(opentracing.Span) Logger {}

func FromHTTPHeaders(http.Header) Logger {}

func ToHTTPHeaders(Logger, http.Header) {}

type Logger interface {
	// Lifecycle
	Start(name string, data ...Data) Logger
	Succeed(data ...Data)
	Fail(error,data ...Data)

	// Log Levels
	Debug(action string, data ...Data)
	Info(action string, data ...Data)
	Error(action string, err error, data ...Data)
	Fatal(action string, err error, data ...Data)

	// WithData returns a logger which adds Data to be serialized
	// on all subsequent local logs
	WithData(Data) Logger

	// WithBaggage returns a logger which adds Data to be serialized
	// on all subsequent rpc calls. Very expensive.
	WithBaggage(Data) Logger

	// Span enables opentracing compliance
	Span() opentracing.Span

	// Context creates a new Context if one has not been set
	Context() context.Context
	WithContext(context.Context) Logger
	
	// Loggers can print their current operation name
	String() string
}