add tsnet experiment

experiment/tsnet-load/main.go

@@ -0,0 +1,166 @@
+// tsnet-load launches N userspace Tailscale nodes and has each one periodically
+// ping a tailnet peer (or HTTP-GET a subnet-routed host).
+//
+// Usage:
+//
+//	TS_AUTHKEY=tskey-... go run . -count 10 -interval 5s
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"math/rand/v2"
+	"net/http"
+	"net/netip"
+	"os"
+	"os/signal"
+	"path/filepath"
+	"sync"
+	"syscall"
+	"time"
+
+	"tailscale.com/client/tailscale"
+	"tailscale.com/ipn"
+	"tailscale.com/tailcfg"
+	"tailscale.com/tsnet"
+)
+
+const (
+	httpTarget = "http://10.210.1.2"
+	pingTarget = "100.92.123.72"
+)
+
+func main() {
+	authKey := flag.String("authkey", os.Getenv("TS_AUTHKEY"),
+		"Tailscale reusable ephemeral auth key (or set TS_AUTHKEY).")
+	count := flag.Int("count", 10, "Number of tsnet nodes to launch.")
+	interval := flag.Duration("interval", 5*time.Second, "Interval between actions per node.")
+	hostnamePrefix := flag.String("hostname-prefix", "uncloud", "Hostname prefix for tsnet nodes.")
+	stateRoot := flag.String("state-dir", "./state", "Directory to keep tsnet state (default: a fresh temp dir).")
+	flag.Parse()
+
+	if *authKey == "" {
+		log.Fatal("missing Tailscale auth key: pass -authkey or set TS_AUTHKEY.")
+	}
+
+	root := *stateRoot
+	if root == "" {
+		var err error
+		root, err = os.MkdirTemp("", "tsnet-load-*")
+		if err != nil {
+			log.Fatalf("mktemp: %v", err)
+		}
+		defer os.RemoveAll(root)
+	} else if err := os.MkdirAll(root, 0o700); err != nil {
+		log.Fatalf("mkdir state dir: %v", err)
+	}
+
+	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
+	defer stop()
+
+	var wg sync.WaitGroup
+	for i := 0; i < *count; i++ {
+		wg.Add(1)
+		go func(id int) {
+			defer wg.Done()
+			runNode(ctx, id, *authKey, *hostnamePrefix, root, *interval)
+		}(i)
+	}
+	wg.Wait()
+}
+
+func runNode(ctx context.Context, id int, authKey, prefix, stateRoot string, interval time.Duration) {
+	logPrefix := fmt.Sprintf("[node-%02d] ", id)
+	logger := log.New(os.Stderr, logPrefix, log.LstdFlags|log.Lmsgprefix)
+
+	s := &tsnet.Server{
+		Hostname:  fmt.Sprintf("%s-%02d", prefix, id),
+		AuthKey:   authKey,
+		Ephemeral: true,
+		Dir:       filepath.Join(stateRoot, fmt.Sprintf("node-%02d", id)),
+		// Silence per-node tsnet chatter. Comment out to debug.
+		Logf: func(string, ...any) {},
+	}
+	defer s.Close()
+
+	upCtx, cancel := context.WithTimeout(ctx, 60*time.Second)
+	defer cancel()
+	status, err := s.Up(upCtx)
+	if err != nil {
+		logger.Printf("tsnet up: %v", err)
+		return
+	}
+	logger.Printf("up as %s (%v)", s.Hostname, status.TailscaleIPs)
+
+	// Accept subnet routes advertised by other tailnet peers. tsnet defaults
+	// to RouteAll=false, so without this 10.210.0.0/24 etc. are unreachable.
+	lc, err := s.LocalClient()
+	if err != nil {
+		logger.Printf("local client: %v", err)
+		return
+	}
+	if _, err := lc.EditPrefs(ctx, &ipn.MaskedPrefs{
+		RouteAllSet: true,
+		Prefs:       ipn.Prefs{RouteAll: true},
+	}); err != nil {
+		logger.Printf("edit prefs (RouteAll): %v", err)
+		return
+	}
+
+	httpClient := &http.Client{
+		Transport: &http.Transport{DialContext: s.Dial},
+		Timeout:   10 * time.Second,
+	}
+	_ = httpClient
+
+	// Stagger ticks so all nodes don't fire in lockstep.
+	time.Sleep(time.Duration(rand.Int64N(int64(interval))))
+
+	tick := time.NewTicker(interval)
+	defer tick.Stop()
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-tick.C:
+			doPing(ctx, lc, logger)
+			//doHTTP(ctx, httpClient, logger)
+		}
+	}
+}
+
+func doPing(ctx context.Context, lc *tailscale.LocalClient, logger *log.Logger) {
+	pctx, cancel := context.WithTimeout(ctx, 5*time.Second)
+	defer cancel()
+
+	res, err := lc.Ping(pctx, netip.MustParseAddr(pingTarget), tailcfg.PingICMP)
+	if err != nil {
+		logger.Printf("ping %s: %v", pingTarget, err)
+		return
+	}
+	if res.Err != "" {
+		logger.Printf("ping %s: %s", pingTarget, res.Err)
+		return
+	}
+	logger.Printf("ping %s ok in %.1fms via %s", pingTarget, res.LatencySeconds*1000, res.Endpoint)
+}
+
+func doHTTP(ctx context.Context, c *http.Client, logger *log.Logger) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, httpTarget, nil)
+	if err != nil {
+		logger.Printf("http build req: %v", err)
+		return
+	}
+	start := time.Now()
+	resp, err := c.Do(req)
+	if err != nil {
+		logger.Printf("http %s: %v", httpTarget, err)
+		return
+	}
+	defer resp.Body.Close()
+	n, _ := io.Copy(io.Discard, resp.Body)
+	logger.Printf("http %s: %s, %d bytes in %v", httpTarget, resp.Status, n, time.Since(start).Round(time.Millisecond))
+}