Basic span definitions (#49)

* use directly the trace middleware instead of the fancy tracing service

* cannot rely on mux middlewares

* add hops

pkg/middleware/static.go

@@ -3,6 +3,8 @@ package middleware
 import (
 	"net/http"
 	"strings"
+
+	"go.opencensus.io/trace"
 )
 
 // Static is a middleware that serves static assets.
@@ -20,17 +22,32 @@ func Static(root string, fs http.FileSystem) func(http.Handler) http.Handler {
 
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			ctx, span := trace.StartSpan(r.Context(), "serve static asset")
+			defer span.End()
+			r = r.WithContext(ctx)
+
 			// serve the static assets for the identifier web app
 			if strings.HasPrefix(r.URL.Path, "/signin/v1/static/") {
 				if strings.HasSuffix(r.URL.Path, "/") {
 					// but no listing of folders
+					span.AddAttributes(trace.StringAttribute("asset not found", r.URL.Path))
+					span.SetStatus(trace.Status{
+						Code:    1,
+						Message: "asset not found",
+					})
 					http.NotFound(w, r)
 				} else {
 					r.URL.Path = strings.Replace(r.URL.Path, "/signin/v1/static/", "/signin/v1/identifier/static/", 1)
+					span.AddAttributes(trace.StringAttribute("served", r.URL.Path))
 					static.ServeHTTP(w, r)
 				}
 				return
 			}
+			span.AddAttributes(trace.StringAttribute("served", r.URL.Path))
+			span.SetStatus(trace.Status{
+				Code:    0,
+				Message: "ok",
+			})
 			next.ServeHTTP(w, r)
 		})
 	}