tr/service_hook: prevent Update from running before Poststart has finished

client/allocrunner/taskrunner/service_hook.go

@@ -48,6 +48,10 @@ type serviceHook struct {
 	networks   structs.Networks
 	taskEnv    *taskenv.TaskEnv
 
+	// initialRegistrations tracks if Poststart has completed, initializing
+	// fields required in other lifecycle funcs
+	initialRegistration bool
+
 	// Since Update() may be called concurrently with any other hook all
 	// hook methods must be fully serialized
 	mu sync.Mutex
@@ -91,12 +95,17 @@ func (h *serviceHook) Poststart(ctx context.Context, req *interfaces.TaskPoststa
 	// Create task services struct with request's driver metadata
 	workloadServices := h.getWorkloadServices()
 
+	defer func() { h.initialRegistration = true }()
 	return h.consul.RegisterWorkload(workloadServices)
 }
 
 func (h *serviceHook) Update(ctx context.Context, req *interfaces.TaskUpdateRequest, _ *interfaces.TaskUpdateResponse) error {
 	h.mu.Lock()
 	defer h.mu.Unlock()
+	if !h.initialRegistration {
+		// no op since initial registration has not finished
+		return nil
+	}
 
 	// Create old task services struct with request's driver metadata as it
 	// can't change due to Updates

client/allocrunner/taskrunner/service_hook_test.go

@@ -1,7 +1,14 @@
 package taskrunner
 
 import (
+	"context"
+	"testing"
+
 	"github.com/hashicorp/nomad/client/allocrunner/interfaces"
+	"github.com/hashicorp/nomad/client/consul"
+	"github.com/hashicorp/nomad/helper/testlog"
+	"github.com/hashicorp/nomad/nomad/mock"
+	"github.com/stretchr/testify/require"
 )
 
 // Statically assert the stats hook implements the expected interfaces
@@ -9,3 +16,22 @@ var _ interfaces.TaskPoststartHook = (*serviceHook)(nil)
 var _ interfaces.TaskExitedHook = (*serviceHook)(nil)
 var _ interfaces.TaskPreKillHook = (*serviceHook)(nil)
 var _ interfaces.TaskUpdateHook = (*serviceHook)(nil)
+
+func TestUpdate_beforePoststart(t *testing.T) {
+	alloc := mock.Alloc()
+	logger := testlog.HCLogger(t)
+	c := consul.NewMockConsulServiceClient(t, logger)
+
+	hook := newServiceHook(serviceHookConfig{
+		alloc:  alloc,
+		task:   alloc.LookupTask("web"),
+		consul: c,
+		logger: logger,
+	})
+	require.NoError(t, hook.Update(context.Background(), &interfaces.TaskUpdateRequest{Alloc: alloc}, &interfaces.TaskUpdateResponse{}))
+	require.Len(t, c.GetOps(), 0)
+	require.NoError(t, hook.Poststart(context.Background(), &interfaces.TaskPoststartRequest{}, &interfaces.TaskPoststartResponse{}))
+	require.Len(t, c.GetOps(), 1)
+	require.NoError(t, hook.Update(context.Background(), &interfaces.TaskUpdateRequest{Alloc: alloc}, &interfaces.TaskUpdateResponse{}))
+	require.Len(t, c.GetOps(), 2)
+}