72 lines
1.7 KiB
Go
72 lines
1.7 KiB
Go
package main
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import (
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"context"
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"embed"
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"flag"
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"html/template"
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"log"
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"net/http"
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"os"
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"os/signal"
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"strconv"
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"syscall"
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)
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//go:embed templates
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var templatesFS embed.FS
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func main() {
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listen := flag.String("listen", envOr("FRONTEND_LISTEN", ":8080"), "HTTP listen address (env: FRONTEND_LISTEN)")
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target := flag.String("target", envOr("FRONTEND_TARGET", "localhost:9091"), "default gRPC endpoint, aggregator or collector (env: FRONTEND_TARGET)")
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n := flag.Int("n", envOrInt("FRONTEND_N", 25), "default number of table rows (env: FRONTEND_N)")
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refresh := flag.Int("refresh", envOrInt("FRONTEND_REFRESH", 30), "meta-refresh interval in seconds, 0 to disable (env: FRONTEND_REFRESH)")
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flag.Parse()
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funcMap := template.FuncMap{"fmtCount": fmtCount}
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tmpl := template.Must(
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template.New("").Funcs(funcMap).ParseFS(templatesFS, "templates/*.html"),
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)
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h := &Handler{
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defaultTarget: *target,
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defaultN: *n,
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refreshSecs: *refresh,
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tmpl: tmpl,
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}
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srv := &http.Server{Addr: *listen, Handler: h}
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ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
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defer stop()
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go func() {
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log.Printf("frontend: listening on %s (default target %s)", *listen, *target)
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if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
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log.Printf("frontend: %v", err)
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os.Exit(1)
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}
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}()
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<-ctx.Done()
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log.Printf("frontend: shutting down")
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srv.Shutdown(context.Background())
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}
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func envOr(key, def string) string {
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if v := os.Getenv(key); v != "" {
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return v
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}
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return def
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}
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func envOrInt(key string, def int) int {
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if v := os.Getenv(key); v != "" {
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if n, err := strconv.Atoi(v); err == nil {
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return n
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}
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log.Printf("frontend: invalid int for %s=%q, using default %d", key, v, def)
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}
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return def
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}
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