Execute PLAN_FRONTEND.md

cmd/frontend/main.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"context"
+	"embed"
+	"flag"
+	"html/template"
+	"log"
+	"net/http"
+	"os"
+	"os/signal"
+	"syscall"
+)
+
+//go:embed templates
+var templatesFS embed.FS
+
+func main() {
+	listen  := flag.String("listen", ":8080", "HTTP listen address")
+	target  := flag.String("target", "localhost:9091", "default gRPC endpoint (aggregator or collector)")
+	n       := flag.Int("n", 25, "default number of table rows")
+	refresh := flag.Int("refresh", 30, "meta-refresh interval in seconds (0 = disabled)")
+	flag.Parse()
+
+	funcMap := template.FuncMap{"fmtCount": fmtCount}
+	tmpl := template.Must(
+		template.New("").Funcs(funcMap).ParseFS(templatesFS, "templates/*.html"),
+	)
+
+	h := &Handler{
+		defaultTarget: *target,
+		defaultN:      *n,
+		refreshSecs:   *refresh,
+		tmpl:          tmpl,
+	}
+
+	srv := &http.Server{Addr: *listen, Handler: h}
+
+	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
+	defer stop()
+
+	go func() {
+		log.Printf("frontend: listening on %s (default target %s)", *listen, *target)
+		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+			log.Printf("frontend: %v", err)
+			os.Exit(1)
+		}
+	}()
+
+	<-ctx.Done()
+	log.Printf("frontend: shutting down")
+	srv.Shutdown(context.Background())
+}