tailscale/tsnet

tsnet

Package tsnet embeds a Tailscale node directly into a Go program, allowing it to join a tailnet and accept or dial connections without running a separate tailscaled daemon or requiring any system-level configuration.

Overview

Normally, Tailscale runs as a background system service (tailscaled) that manages a virtual network interface for the whole machine. tsnet takes a different approach: it runs a fully self-contained Tailscale node inside your process using a userspace TCP/IP stack (gVisor). This means:

• No root privileges required.
• No system daemons to install or manage.
• Multiple independent Tailscale nodes can run within a single binary.
• The node's Tailscale identity and state are stored in a directory you control.

The core type is Server, which represents one embedded Tailscale node. Calling Server.Listen or Server.Dial routes traffic exclusively over the tailnet. The standard library's net.Listener and net.Conn interfaces are returned, so any existing Go HTTP server, gRPC server, or other net-based code works without modification.

Usage

import "tailscale.com/tsnet"

s := &tsnet.Server{
	Hostname: "my-service",
	AuthKey:  os.Getenv("TS_AUTHKEY"),
}
defer s.Close()

ln, err := s.Listen("tcp", ":80")
if err != nil {
	log.Fatal(err)
}
log.Fatal(http.Serve(ln, myHandler))

On first run, if no Server.AuthKey is provided and the node is not already enrolled, the server logs an authentication URL. Open it in a browser to add the node to your tailnet.

Authentication

A Server authenticates using, in order of precedence:

1. Server.AuthKey.

2. The TS_AUTHKEY environment variable.

3. The TS_AUTH_KEY environment variable.

4. An OAuth client secret (Server.ClientSecret or TS_CLIENT_SECRET), used to mint an auth key.

5. Workload identity federation (Server.ClientID plus Server.IDToken or Server.Audience). Available only if the program imports the feature:

   import _ "tailscale.com/feature/identityfederation"

   The feature is not linked by default to keep the AWS SDK and other cloud-provider dependencies out of programs that don't use workload identity federation.

6. An interactive login URL printed to Server.UserLogf.

If the node is already enrolled (state found in Server.Store), the auth key is ignored unless TSNET_FORCE_LOGIN=1 is set.

Identifying callers

Use the WhoIs method on the client returned by Server.LocalClient to identify who is making a request:

lc, _ := srv.LocalClient()
http.Serve(ln, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
	who, err := lc.WhoIs(r.Context(), r.RemoteAddr)
	if err != nil {
		http.Error(w, err.Error(), 500)
		return
	}
	fmt.Fprintf(w, "Hello, %s!", who.UserProfile.LoginName)
}))

Tailscale Funnel

Server.ListenFunnel exposes your service on the public internet. Tailscale Funnel currently supports TCP on ports 443, 8443, and 10000. HTTPS must be enabled in the Tailscale admin console.

ln, err := srv.ListenFunnel("tcp", ":443")
// ln is a TLS listener; connections can come from anywhere on the
// internet as well as from your tailnet.

// To restrict to public traffic only:
ln, err = srv.ListenFunnel("tcp", ":443", tsnet.FunnelOnly())

Tailscale Services

Server.ListenService advertises the node as a host for a named Tailscale Service. The node must use a tag-based identity. To advertise multiple ports, call ListenService once per port.

srv.AdvertiseTags = []string{"tag:myservice"}

ln, err := srv.ListenService("svc:my-service", tsnet.ServiceModeHTTP{
	HTTPS: true,
	Port:  443,
})
log.Printf("Listening on https://%s", ln.FQDN)

Using an exit node

A tsnet node can route its Server.Dial traffic to non-tailnet addresses through an exit node. Select the exit node by setting the ExitNodeID pref via Server.LocalClient:

lc, _ := srv.LocalClient()
_, err := lc.EditPrefs(ctx, &ipn.MaskedPrefs{
	Prefs:         ipn.Prefs{ExitNodeID: "nodeid"},
	ExitNodeIDSet: true,
})

Dials of addresses outside the tailnet then go through the exit node. Dials within the tailnet are unaffected.

DNS resolution

Server.Dial and Server.HTTPClient resolve names using the tailnet's DNS configuration first, falling back to the host resolver for names without a configured upstream or local answer. Server.LookupIP provides direct lookups:

ips, err := srv.LookupIP(ctx, "ip", "db")

Running multiple nodes in one process

Each Server instance is an independent node. Give each a unique Server.Dir and Server.Hostname:

for _, name := range []string{"frontend", "backend"} {
	srv := &tsnet.Server{
		Hostname:  name,
		Dir:       filepath.Join(baseDir, name),
		AuthKey:   os.Getenv("TS_AUTHKEY"),
		Ephemeral: true,
	}
	srv.Start()
}