78 lines
1.9 KiB
Go
78 lines
1.9 KiB
Go
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package main
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import (
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"bytes"
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"encoding/json"
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"html/template"
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"io/ioutil"
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"math/rand"
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"net/http"
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"os"
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"time"
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"github.com/prometheus/client_golang/prometheus/promhttp"
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"github.com/prometheus/client_golang/prometheus"
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)
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type Image struct {
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Url string `json:"url"`
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Caption string `json:"caption"`
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Copyright string `json:"copyright"`
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}
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type AccessLog struct {
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ClientIP string `json:"clientIp"`
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}
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func main() {
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tmpl := template.Must(template.ParseFiles("index.html"))
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imageApiUrl := os.Getenv("IMAGE_API_URL")
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logApiUrl := os.Getenv("ACCESS_API_URL")
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//re-use HTTP client with minimal keep-alive
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tr := &http.Transport{
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MaxIdleConns: 1,
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IdleConnTimeout: 1 * time.Second,
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}
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client := &http.Client{Transport: tr}
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//create Prometheus metrics
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inFlightGauge := prometheus.NewGauge(prometheus.GaugeOpts{
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Name: "image_gallery_in_flight_requests",
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Help: "Image Gallery - in-flight requests",
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})
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requestCounter := prometheus.NewCounterVec(
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prometheus.CounterOpts{
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Name: "image_gallery_requests_total",
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Help: "Image Gallery - total requests",
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},
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[]string{"code", "method"},
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)
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prometheus.MustRegister(inFlightGauge, requestCounter)
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rand.Seed(time.Now().UnixNano())
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indexHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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response,_ := client.Get(imageApiUrl)
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defer response.Body.Close()
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data,_ := ioutil.ReadAll(response.Body)
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image := Image{}
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json.Unmarshal([]byte(data), &image)
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tmpl.Execute(w, image)
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log := AccessLog{
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ClientIP: r.RemoteAddr,
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}
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jsonLog,_ := json.Marshal(log)
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response,_ = client.Post(logApiUrl, "application/json", bytes.NewBuffer(jsonLog))
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defer response.Body.Close()
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})
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wrappedIndexHandler := promhttp.InstrumentHandlerInFlight(inFlightGauge,
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promhttp.InstrumentHandlerCounter(requestCounter, indexHandler))
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http.Handle("/", wrappedIndexHandler)
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http.Handle("/metrics", promhttp.Handler())
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http.ListenAndServe(":80", nil)
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}
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