ipn/store: add common package for instantiating ipn.StateStores

Also move KubeStore and MemStore into their own package.

RELNOTE: tsnet now supports providing a custom ipn.StateStore.

Signed-off-by: Maisem Ali <maisem@tailscale.com>

ipn/ipnlocal/local_test.go

@@ -14,6 +14,7 @@ import (
 
 	"inet.af/netaddr"
 	"tailscale.com/ipn"
+	"tailscale.com/ipn/store/mem"
 	"tailscale.com/net/interfaces"
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/tailcfg"
@@ -457,7 +458,7 @@ func TestLazyMachineKeyGeneration(t *testing.T) {
 	panicOnMachineKeyGeneration = true
 
 	var logf logger.Logf = logger.Discard
-	store := new(ipn.MemoryStore)
+	store := new(mem.Store)
 	eng, err := wgengine.NewFakeUserspaceEngine(logf, 0)
 	if err != nil {
 		t.Fatalf("NewFakeUserspaceEngine: %v", err)

ipn/ipnlocal/loglines_test.go

@@ -11,6 +11,7 @@ import (
 
 	"tailscale.com/ipn"
 	"tailscale.com/ipn/ipnstate"
+	"tailscale.com/ipn/store/mem"
 	"tailscale.com/logtail"
 	"tailscale.com/tailcfg"
 	"tailscale.com/tstest"
@@ -47,7 +48,7 @@ func TestLocalLogLines(t *testing.T) {
 	idA := logid(0xaa)
 
 	// set up a LocalBackend, super bare bones. No functional data.
-	store := &ipn.MemoryStore{}
+	store := new(mem.Store)
 	e, err := wgengine.NewFakeUserspaceEngine(logf, 0)
 	if err != nil {
 		t.Fatal(err)

ipn/ipnlocal/state_test.go

@@ -14,6 +14,7 @@ import (
 
 	"tailscale.com/control/controlclient"
 	"tailscale.com/ipn"
+	"tailscale.com/ipn/store/mem"
 	"tailscale.com/syncs"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/empty"
@@ -922,7 +923,7 @@ func TestStateMachine(t *testing.T) {
 }
 
 type testStateStorage struct {
-	mem     ipn.MemoryStore
+	mem     mem.Store
 	written syncs.AtomicBool
 }
 
@@ -954,7 +955,7 @@ func TestWGEngineStatusRace(t *testing.T) {
 	eng, err := wgengine.NewFakeUserspaceEngine(logf, 0)
 	c.Assert(err, qt.IsNil)
 	t.Cleanup(eng.Close)
-	b, err := NewLocalBackend(logf, "logid", new(ipn.MemoryStore), nil, eng, 0)
+	b, err := NewLocalBackend(logf, "logid", new(mem.Store), nil, eng, 0)
 	c.Assert(err, qt.IsNil)
 
 	cc := newMockControl(t)