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// Copyright (c) 2019 The Jaeger Authors.
// Copyright (c) 2017 Uber Technologies, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package frontend
import (
"embed"
"encoding/json"
"expvar"
"net/http"
"path"
"strconv"
"time"
"github.com/prometheus/client_golang/prometheus/promhttp"
"go.opentelemetry.io/otel/trace"
"go.uber.org/zap"
"github.com/jaegertracing/jaeger/examples/hotrod/pkg/httperr"
"github.com/jaegertracing/jaeger/examples/hotrod/pkg/log"
"github.com/jaegertracing/jaeger/examples/hotrod/pkg/tracing"
"github.com/jaegertracing/jaeger/pkg/httpfs"
)
//go:embed web_assets/*
var assetFS embed.FS
// Server implements jaeger-demo-frontend service
type Server struct {
hostPort string
tracer trace.TracerProvider
logger log.Factory
bestETA *bestETA
assetFS http.FileSystem
basepath string
jaegerUI string
}
// ConfigOptions used to make sure service clients
// can find correct server ports
type ConfigOptions struct {
FrontendHostPort string
DriverHostPort string
CustomerHostPort string
RouteHostPort string
Basepath string
JaegerUI string
}
// NewServer creates a new frontend.Server
func NewServer(options ConfigOptions, tracer trace.TracerProvider, logger log.Factory) *Server {
return &Server{
hostPort: options.FrontendHostPort,
tracer: tracer,
logger: logger,
bestETA: newBestETA(tracer, logger, options),
assetFS: httpfs.PrefixedFS("web_assets", http.FS(assetFS)),
basepath: options.Basepath,
jaegerUI: options.JaegerUI,
}
}
// Run starts the frontend server
func (s *Server) Run() error {
mux := s.createServeMux()
s.logger.Bg().Info("Starting", zap.String("address", "http://"+path.Join(s.hostPort, s.basepath)))
server := &http.Server{
Addr: s.hostPort,
Handler: mux,
ReadHeaderTimeout: 3 * time.Second,
}
return server.ListenAndServe()
}
func (s *Server) createServeMux() http.Handler {
mux := tracing.NewServeMux(true, s.tracer, s.logger)
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))
mux.Handle(path.Join(p, "/debug/vars"), expvar.Handler()) // expvar
mux.Handle(path.Join(p, "/metrics"), promhttp.Handler()) // Prometheus
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))
if err := r.ParseForm(); httperr.HandleError(w, err, http.StatusBadRequest) {
s.logger.For(ctx).Error("bad request", zap.Error(err))
return
}
customer := r.Form.Get("customer")
if customer == "" {
http.Error(w, "Missing required 'customer' parameter", http.StatusBadRequest)
return
}
customerID, err := strconv.Atoi(customer)
if err != nil {
http.Error(w, "Parameter 'customer' is not an integer", http.StatusBadRequest)
return
}
// TODO distinguish between user errors (such as invalid customer ID) and server failures
response, err := s.bestETA.Get(ctx, customerID)
if httperr.HandleError(w, err, http.StatusInternalServerError) {
s.logger.For(ctx).Error("request failed", zap.Error(err))
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(r.Context()).Error("cannot marshal response", zap.Error(err))
return
}
w.Header().Set("Content-Type", "application/json")
w.Write(data)
}