package main import ( "context" "fmt" "html/template" "net/http" "path/filepath" "time" "christine.website/internal" "christine.website/internal/blog" "github.com/prometheus/client_golang/prometheus" "github.com/prometheus/client_golang/prometheus/promauto" "within.website/ln" "within.website/ln/opname" ) var ( templateRenderTime = promauto.NewHistogramVec(prometheus.HistogramOpts{ Name: "template_render_time", Help: "Template render time in nanoseconds", }, []string{"name"}) ) func logTemplateTime(ctx context.Context, name string, f ln.F, from time.Time) { dur := time.Since(from) templateRenderTime.With(prometheus.Labels{"name": name}).Observe(float64(dur)) ln.Log(ctx, f, ln.F{"dur": dur, "name": name}) } func (s *Site) renderTemplatePage(templateFname string, data interface{}) http.Handler { return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { ctx := opname.With(r.Context(), "renderTemplatePage") fetag := "W/" + internal.Hash(templateFname, etag) + "-1" f := ln.F{"etag": fetag, "if_none_match": r.Header.Get("If-None-Match")} if r.Header.Get("If-None-Match") == fetag { http.Error(w, "Cached data OK", http.StatusNotModified) ln.Log(ctx, f, ln.Info("Cache hit")) return } defer logTemplateTime(ctx, templateFname, f, time.Now()) var t *template.Template var err error t, err = template.ParseFiles("templates/base.html", "templates/"+templateFname) if err != nil { w.WriteHeader(http.StatusInternalServerError) ln.Error(ctx, err, ln.F{"action": "renderTemplatePage", "page": templateFname}) fmt.Fprintf(w, "error: %v", err) } w.Header().Set("ETag", fetag) w.Header().Set("Cache-Control", "max-age=432000") err = t.Execute(w, data) if err != nil { panic(err) } }) } var postView = promauto.NewCounterVec(prometheus.CounterOpts{ Name: "posts_viewed", Help: "The number of views per post", }, []string{"base"}) func (s *Site) showPost(w http.ResponseWriter, r *http.Request) { if r.RequestURI == "/blog/" { http.Redirect(w, r, "/blog", http.StatusSeeOther) return } cmp := r.URL.Path[1:] var p blog.Post var found bool for _, pst := range s.Posts { if pst.Link == cmp { p = pst found = true } } if !found { w.WriteHeader(http.StatusNotFound) s.renderTemplatePage("error.html", "no such post found: "+r.RequestURI).ServeHTTP(w, r) return } const dateFormat = `2006-01-02` s.renderTemplatePage("blogpost.html", struct { Title string Link string BodyHTML template.HTML Date string }{ Title: p.Title, Link: p.Link, BodyHTML: p.BodyHTML, Date: p.Date.Format(dateFormat), }).ServeHTTP(w, r) postView.With(prometheus.Labels{"base": filepath.Base(p.Link)}).Inc() }