[hotrod] Add links to traces

CONTRIBUTING.md

@@ -14,7 +14,7 @@ We gratefully welcome improvements to documentation as well as to code.
 ## Getting Started
 
 ### Pre-requisites
-* Install [Go](https://golang.org/doc/install) and setup GOPATH and add $GOPATH/bin in PATH 
+* Install [Go](https://golang.org/doc/install) and setup GOPATH and add $GOPATH/bin in PATH
 
 This library uses Go modules to manage dependencies.
 
@@ -116,18 +116,32 @@ import (
 
 ## Testing guidelines
 
-We strive to maintain as high code coverage as possible. Since `go test` command does not generate
+We strive to maintain as high code coverage as possible. The current repository limit is set at 95%,
+with some exclusions discussed below.
+
+### Combining code coverage
+
+We use [cover.sh](./scripts/cover.sh) script to run tests and combine code coverage from all packages
+(see also [issue # 797](https://github.com/jaegertracing/jaeger/issues/797)).
+
+### Packages with no tests
+
+Since `go test` command does not generate
 code coverage information for packages that have no test files, we have a build step (`make nocover`)
-that breaks the build when such packages are discovered, with an error like this:
+that breaks the build when such packages are discovered, with the following error:
 
 ```
 error: at least one *_test.go file must be in all directories with go files
        so that they are counted for code coverage.
        If no tests are possible for a package (e.g. it only defines types), create empty_test.go
 ```
 
+As the message says, all packages are required to have at least one `*_test.go` file.
+
+### Excluding packages from testing
+
 There are conditions that cannot be tested without external dependencies, such as a function that
-creates a gocql.Session, because it requires an active connection to Cassandra database. It is
+creates a `gocql.Session`, because it requires an active connection to Cassandra database. It is
 recommended to isolate such functions in a separate package with bare minimum of code and add a
 file `.nocover` to exclude the package from coverage calculations. The file should contain
 a comment explaining why it is there, for example:
@@ -145,4 +159,3 @@ Before merging a PR make sure:
 
 Merge the PR by using "Squash and merge" option on Github. Avoid creating merge commits.
 After the merge make sure referenced issues were closed.
-

examples/hotrod/README.md

@@ -47,8 +47,8 @@ Jaeger UI can be accessed at http://localhost:16686.
 
 ```bash
 git clone [email protected]:jaegertracing/jaeger.git jaeger
-cd jaeger/examples/hotrod
-go run ./main.go all
+cd jaeger
+go run ./examples/hotrod/main.go all
 ```
 
 ### Run HotROD from docker
@@ -73,3 +73,14 @@ The app exposes metrics in either Go's `expvar` format (by default) or in Promet
 
 [hotrod-tutorial]: https://medium.com/@YuriShkuro/take-opentracing-for-a-hotrod-ride-f6e3141f7941
 [hotrod-openshift]: https://blog.openshift.com/openshift-commons-briefing-82-distributed-tracing-with-jaeger-prometheus-on-kubernetes/
+
+## Linking to traces
+
+The HotROD UI can generate links to the Jaeger UI to find traces corresponding
+to each executed request. By default it uses the standard Jaeger UI address
+http://localhost:16686, but if your Jaeger UI is running at a different address,
+it can be customized via `-j <address>` flag passed to HotROD, e.g.
+
+```
+go run ./examples/hotrod/main.go all -j http://jaeger-ui:16686
+```

examples/hotrod/cmd/frontend.go

@@ -39,6 +39,7 @@ var frontendCmd = &cobra.Command{
 		options.CustomerHostPort = net.JoinHostPort("0.0.0.0", strconv.Itoa(customerPort))
 		options.RouteHostPort = net.JoinHostPort("0.0.0.0", strconv.Itoa(routePort))
 		options.Basepath = basepath
+		options.JaegerUI = jaegerUI
 
 		zapLogger := logger.With(zap.String("service", "frontend"))
 		logger := log.NewFactory(zapLogger)

examples/hotrod/cmd/root.go

@@ -45,6 +45,7 @@ var (
 	routePort    int
 
 	basepath string
+	jaegerUI string
 )
 
 // RootCmd represents the base command when called without any subcommands
@@ -77,6 +78,7 @@ func init() {
 
 	// Flag for serving frontend at custom basepath url
 	RootCmd.PersistentFlags().StringVarP(&basepath, "basepath", "b", "", `Basepath for frontend service(default "/")`)
+	RootCmd.PersistentFlags().StringVarP(&jaegerUI, "jaeger-ui", "j", "http://localhost:16686", "Address of Jaeger UI to create [find trace] links")
 
 	rand.Seed(int64(time.Now().Nanosecond()))
 	logger, _ = zap.NewDevelopment(

examples/hotrod/docker-compose.yml

@@ -14,6 +14,8 @@ services:
     command: ["all"]
     environment:
       - JAEGER_AGENT_HOST=jaeger
+      # Note: if your application is using Node.js Jaeger Client, you need port 6832,
+      #       unless issue https://github.com/jaegertracing/jaeger/issues/1596 is resolved.
       - JAEGER_AGENT_PORT=6831
     networks:
       - jaeger-example

examples/hotrod/services/frontend/server.go

@@ -36,6 +36,7 @@ type Server struct {
 	bestETA  *bestETA
 	assetFS  http.FileSystem
 	basepath string
+	jaegerUI string
 }
 
 // ConfigOptions used to make sure service clients
@@ -46,6 +47,7 @@ type ConfigOptions struct {
 	CustomerHostPort string
 	RouteHostPort    string
 	Basepath         string
+	JaegerUI         string
 }
 
 // NewServer creates a new frontend.Server
@@ -58,6 +60,7 @@ func NewServer(options ConfigOptions, tracer opentracing.Tracer, logger log.Fact
 		bestETA:  newBestETA(tracer, logger, options),
 		assetFS:  assetFS,
 		basepath: options.Basepath,
+		jaegerUI: options.JaegerUI,
 	}
 }
 
@@ -73,9 +76,17 @@ func (s *Server) createServeMux() http.Handler {
 	p := path.Join("/", s.basepath)
 	mux.Handle(p, http.StripPrefix(p, http.FileServer(s.assetFS)))
 	mux.Handle(path.Join(p, "/dispatch"), http.HandlerFunc(s.dispatch))
+	mux.Handle(path.Join(p, "/config"), http.HandlerFunc(s.config))
 	return mux
 }
 
+func (s *Server) config(w http.ResponseWriter, r *http.Request) {
+	config := map[string]string{
+		"jaeger": s.jaegerUI,
+	}
+	s.writeResponse(config, w, r)
+}
+
 func (s *Server) dispatch(w http.ResponseWriter, r *http.Request) {
 	ctx := r.Context()
 	s.logger.For(ctx).Info("HTTP request received", zap.String("method", r.Method), zap.Stringer("url", r.URL))
@@ -97,9 +108,13 @@ func (s *Server) dispatch(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	s.writeResponse(response, w, r)
+}
+
+func (s *Server) writeResponse(response interface{}, w http.ResponseWriter, r *http.Request) {
 	data, err := json.Marshal(response)
 	if httperr.HandleError(w, err, http.StatusInternalServerError) {
-		s.logger.For(ctx).Error("cannot marshal response", zap.Error(err))
+		s.logger.For(r.Context()).Error("cannot marshal response", zap.Error(err))
 		return
 	}
 

examples/hotrod/services/frontend/web_assets/index.html

@@ -61,7 +61,7 @@ <h4><em>Rides On Demand</em></h4>
 var clientUUID = Math.round(Math.random() * 10000);
 var lastRequestID = 0;
 
-$(".uuid").html("Your web client's id: <strong>" + clientUUID + "</strong>");
+$(".uuid").html(`Your web client's id: <strong>${clientUUID}</strong>`);
 
 $(".hotrod-button").click(function(evt) {
   lastRequestID++;
@@ -78,14 +78,30 @@ <h4><em>Rides On Demand</em></h4>
   var pathPrefix = window.location.pathname;
   pathPrefix = pathPrefix != "/" ? pathPrefix : '';
 
+  var config = {};
+  $.ajax(pathPrefix + '/config?nonse=' + Math.random(), {
+    method: 'GET',
+    success: function(data, textStatus) {
+      var after = Date.now();
+      console.log(data);
+      config = data;
+    },
+  });
+
   $.ajax(pathPrefix + '/dispatch?customer=' + customer + '&nonse=' + Math.random(), {
     headers: headers,
     method: 'GET',
     success: function(data, textStatus) {
       var after = Date.now();
       console.log(data);
       var duration = formatDuration(data.ETA);
-      freshCar.html('HotROD <b>' + data.Driver + '</b> arriving in ' + duration + ' [req: ' + requestID + ', latency: ' + (after-before) + 'ms]');
+      var traceLink = '';
+      if (config && config['jaeger']) {
+        var jaeger = config['jaeger'];
+        var trace = `${jaeger}/search?limit=20&lookback=1h&service=frontend&tags=%7B%22driver%22%3A%22${data.Driver}%22%7D`;
+        traceLink = ` [<a href="${trace}" target="_blank">find trace</a>]`;
+      }
+      freshCar.html(`HotROD <b>${data.Driver}</b> arriving in ${duration} [req: ${requestID}, latency: ${after-before}ms] ${traceLink}`);
     },
   });
 });