feat: add agent acks to in-memory coordinator (#12786)

When an agent receives a node, it responds with an ACK which is relayed
to the client. After the client receives the ACK, it's allowed to begin
pinging.

codersdk/workspacesdk/connector_internal_test.go

@@ -0,0 +1,109 @@
+package workspacesdk
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"nhooyr.io/websocket"
+	"tailscale.com/tailcfg"
+
+	"cdr.dev/slog"
+	"cdr.dev/slog/sloggers/slogtest"
+	"github.com/coder/coder/v2/codersdk"
+	"github.com/coder/coder/v2/tailnet"
+	"github.com/coder/coder/v2/tailnet/proto"
+	"github.com/coder/coder/v2/tailnet/tailnettest"
+	"github.com/coder/coder/v2/testutil"
+)
+
+func TestTailnetAPIConnector_Disconnects(t *testing.T) {
+	t.Parallel()
+	testCtx := testutil.Context(t, testutil.WaitShort)
+	ctx, cancel := context.WithCancel(testCtx)
+	logger := slogtest.Make(t, &slogtest.Options{
+		// we get EOF when we simulate a DERPMap error
+		IgnoredErrorIs: append(slogtest.DefaultIgnoredErrorIs, io.EOF),
+	}).Leveled(slog.LevelDebug)
+	agentID := uuid.UUID{0x55}
+	clientID := uuid.UUID{0x66}
+	fCoord := tailnettest.NewFakeCoordinator()
+	var coord tailnet.Coordinator = fCoord
+	coordPtr := atomic.Pointer[tailnet.Coordinator]{}
+	coordPtr.Store(&coord)
+	derpMapCh := make(chan *tailcfg.DERPMap)
+	defer close(derpMapCh)
+	svc, err := tailnet.NewClientService(
+		logger, &coordPtr,
+		time.Millisecond, func() *tailcfg.DERPMap { return <-derpMapCh },
+	)
+	require.NoError(t, err)
+
+	svr := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		sws, err := websocket.Accept(w, r, nil)
+		if !assert.NoError(t, err) {
+			return
+		}
+		ctx, nc := codersdk.WebsocketNetConn(r.Context(), sws, websocket.MessageBinary)
+		err = svc.ServeConnV2(ctx, nc, tailnet.StreamID{
+			Name: "client",
+			ID:   clientID,
+			Auth: tailnet.ClientCoordinateeAuth{AgentID: agentID},
+		})
+		assert.NoError(t, err)
+	}))
+
+	fConn := newFakeTailnetConn()
+
+	uut := runTailnetAPIConnector(ctx, logger, agentID, svr.URL, &websocket.DialOptions{}, fConn)
+
+	call := testutil.RequireRecvCtx(ctx, t, fCoord.CoordinateCalls)
+	reqTun := testutil.RequireRecvCtx(ctx, t, call.Reqs)
+	require.NotNil(t, reqTun.AddTunnel)
+
+	_ = testutil.RequireRecvCtx(ctx, t, uut.connected)
+
+	// simulate a problem with DERPMaps by sending nil
+	testutil.RequireSendCtx(ctx, t, derpMapCh, nil)
+
+	// this should cause the coordinate call to hang up WITHOUT disconnecting
+	reqNil := testutil.RequireRecvCtx(ctx, t, call.Reqs)
+	require.Nil(t, reqNil)
+
+	// ...and then reconnect
+	call = testutil.RequireRecvCtx(ctx, t, fCoord.CoordinateCalls)
+	reqTun = testutil.RequireRecvCtx(ctx, t, call.Reqs)
+	require.NotNil(t, reqTun.AddTunnel)
+
+	// canceling the context should trigger the disconnect message
+	cancel()
+	reqDisc := testutil.RequireRecvCtx(testCtx, t, call.Reqs)
+	require.NotNil(t, reqDisc)
+	require.NotNil(t, reqDisc.Disconnect)
+}
+
+type fakeTailnetConn struct{}
+
+func (*fakeTailnetConn) UpdatePeers([]*proto.CoordinateResponse_PeerUpdate) error {
+	// TODO implement me
+	panic("implement me")
+}
+
+func (*fakeTailnetConn) SetAllPeersLost() {}
+
+func (*fakeTailnetConn) SetNodeCallback(func(*tailnet.Node)) {}
+
+func (*fakeTailnetConn) SetDERPMap(*tailcfg.DERPMap) {}
+
+func (*fakeTailnetConn) SetTunnelDestination(uuid.UUID) {}
+
+func newFakeTailnetConn() *fakeTailnetConn {
+	return &fakeTailnetConn{}
+}