cmd,tsnet,internal/client: create internal shim to deprecated control plane API

Even after we remove the deprecated API, we will want to maintain a minimal
API for internal use, in order to avoid importing the external
tailscale.com/client/tailscale/v2 package. This shim exposes only the necessary
parts of the deprecated API for internal use, which gains us the following:

1. It removes deprecation warnings for internal use of the API.
2. It gives us an inventory of which parts we will want to keep for internal use.

Updates tailscale/corp#22748

Signed-off-by: Percy Wegmann <percy@tailscale.com>

cmd/get-authkey/main.go

@@ -16,14 +16,10 @@ import (
 	"strings"
 
 	"golang.org/x/oauth2/clientcredentials"
-	"tailscale.com/client/tailscale"
+	"tailscale.com/internal/client/tailscale"
 )
 
 func main() {
-	// Required to use our client API. We're fine with the instability since the
-	// client lives in the same repo as this code.
-	tailscale.I_Acknowledge_This_API_Is_Unstable = true
-
 	reusable := flag.Bool("reusable", false, "allocate a reusable authkey")
 	ephemeral := flag.Bool("ephemeral", false, "allocate an ephemeral authkey")
 	preauth := flag.Bool("preauth", true, "set the authkey as pre-authorized")

cmd/k8s-operator/depaware.txt

@@ -811,6 +811,7 @@ tailscale.com/cmd/k8s-operator dependencies: (generated by github.com/tailscale/
         tailscale.com/health                                         from tailscale.com/control/controlclient+
         tailscale.com/health/healthmsg                               from tailscale.com/ipn/ipnlocal
         tailscale.com/hostinfo                                       from tailscale.com/client/web+
+        tailscale.com/internal/client/tailscale                      from tailscale.com/cmd/k8s-operator
         tailscale.com/internal/noiseconn                             from tailscale.com/control/controlclient
         tailscale.com/ipn                                            from tailscale.com/client/local+
         tailscale.com/ipn/conffile                                   from tailscale.com/ipn/ipnlocal+

cmd/k8s-operator/e2e/main_test.go

@@ -21,7 +21,7 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/client"
 	logf "sigs.k8s.io/controller-runtime/pkg/log"
 	kzap "sigs.k8s.io/controller-runtime/pkg/log/zap"
-	"tailscale.com/client/tailscale"
+	"tailscale.com/internal/client/tailscale"
 )
 
 const (
@@ -64,7 +64,6 @@ func TestMain(m *testing.M) {
 func runTests(m *testing.M) (int, error) {
 	zlog := kzap.NewRaw([]kzap.Opts{kzap.UseDevMode(true), kzap.Level(zapcore.DebugLevel)}...).Sugar()
 	logf.SetLogger(zapr.NewLogger(zlog.Desugar()))
-	tailscale.I_Acknowledge_This_API_Is_Unstable = true
 
 	if clientID := os.Getenv("TS_API_CLIENT_ID"); clientID != "" {
 		cleanup, err := setupClientAndACLs()

cmd/k8s-operator/tsclient.go

@@ -16,7 +16,7 @@ import (
 	"os"
 
 	"golang.org/x/oauth2/clientcredentials"
-	"tailscale.com/client/tailscale"
+	"tailscale.com/internal/client/tailscale"
 	"tailscale.com/tailcfg"
 	"tailscale.com/util/httpm"
 )

cmd/tailscale/cli/up.go

@@ -27,8 +27,8 @@ import (
 	"github.com/peterbourgon/ff/v3/ffcli"
 	qrcode "github.com/skip2/go-qrcode"
 	"golang.org/x/oauth2/clientcredentials"
-	"tailscale.com/client/tailscale"
 	"tailscale.com/health/healthmsg"
+	"tailscale.com/internal/client/tailscale"
 	"tailscale.com/ipn"
 	"tailscale.com/ipn/ipnstate"
 	"tailscale.com/net/netutil"
@@ -1097,12 +1097,6 @@ func exitNodeIP(p *ipn.Prefs, st *ipnstate.Status) (ip netip.Addr) {
 	return
 }
 
-func init() {
-	// Required to use our client API. We're fine with the instability since the
-	// client lives in the same repo as this code.
-	tailscale.I_Acknowledge_This_API_Is_Unstable = true
-}
-
 // resolveAuthKey either returns v unchanged (in the common case) or, if it
 // starts with "tskey-client-" (as Tailscale OAuth secrets do) parses it like
 //

cmd/tailscale/depaware.txt

@@ -93,6 +93,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         tailscale.com/health                                         from tailscale.com/net/tlsdial+
         tailscale.com/health/healthmsg                               from tailscale.com/cmd/tailscale/cli
         tailscale.com/hostinfo                                       from tailscale.com/client/web+
+        tailscale.com/internal/client/tailscale                      from tailscale.com/cmd/tailscale/cli
         tailscale.com/internal/noiseconn                             from tailscale.com/cmd/tailscale/cli
         tailscale.com/ipn                                            from tailscale.com/client/local+
         tailscale.com/ipn/ipnstate                                   from tailscale.com/client/local+