fix: address review findings for self-update (#15)

internal/master/jobs/jobs.go

@@ -40,16 +40,24 @@ type Publisher interface{ Publish(t events.Topic) }
 
 // Service starts update jobs.
 type Service struct {
-	store Store
-	hub   Hub
-	pub   Publisher
-	log   *slog.Logger
-	now   func() time.Time
+	store    Store
+	hub      Hub
+	pub      Publisher
+	selfRepo string
+	log      *slog.Logger
+	now      func() time.Time
 }
 
-// New returns a Service.
-func New(store Store, hub Hub, pub Publisher, log *slog.Logger) *Service {
-	return &Service{store: store, hub: hub, pub: pub, log: log, now: time.Now}
+// New returns a Service. agentImage is the master's AGENT_IMAGE. A service
+// whose image repo equals its repo may be an agent that reports itself as
+// another service (an agent older than protocol version 4 does not tell), so
+// such a job is only sent to an agent that speaks protocol version
+// protocol.MinSelfUpdateVersion.
+func New(store Store, hub Hub, pub Publisher, agentImage string, log *slog.Logger) *Service {
+	return &Service{
+		store: store, hub: hub, pub: pub, log: log, now: time.Now,
+		selfRepo: imageref.Parse(agentImage).Repo,
+	}
 }
 
 // target splits a service's actual ref into the repo and tag to deploy. A bare
@@ -245,7 +253,7 @@ func (s *Service) Start(ctx context.Context, svc model.Service, req StartRequest
 	if p := imageref.Parse(ref); p.Digest != "" || p.Tag == "" {
 		minProtocol = protocol.MinPinnedRefVersion
 	}
-	if svc.Self {
+	if svc.Self || imageref.Parse(svc.ActualRef).Repo == s.selfRepo {
 		minProtocol = protocol.MinSelfUpdateVersion
 	}
 	r, routeErr := s.hub.Route(svc, minProtocol)

internal/master/jobs/jobs_test.go

@@ -16,6 +16,8 @@ import (
 	"github.com/shcizo/package-updater/internal/protocol"
 )
 
+const selfImage = "gitea.shcizo.se/shcizo/package-updater:latest"
+
 type fakeStore struct {
 	services map[int64]model.Service
 	jobs     map[int64]model.Job
@@ -125,7 +127,7 @@ func ptr[T any](v T) *T { return &v }
 
 func newService(st *fakeStore, h *fakeHub) (*Service, *fakePub) {
 	pub := &fakePub{}
-	return New(st, h, pub, slog.New(slog.NewTextHandler(io.Discard, nil))), pub
+	return New(st, h, pub, selfImage, slog.New(slog.NewTextHandler(io.Discard, nil))), pub
 }
 
 func TestUpdatable(t *testing.T) {
@@ -417,6 +419,20 @@ func TestStart_SelfServiceNeedsASelfUpdatingAgent(t *testing.T) {
 		require.Len(t, h.starts, 1)
 		assert.True(t, h.starts[0].start.Self)
 	})
+	t.Run("a service with the agent image repo needs a self-updating agent but is not marked", func(t *testing.T) {
+		svc := composeSvc
+		svc.ActualRef = selfImage
+		st := &fakeStore{services: map[int64]model.Service{1: svc}, jobs: map[int64]model.Job{}}
+		h := &fakeHub{route: ok}
+		s, _ := newService(st, h)
+
+		_, err := s.Start(context.Background(), svc, StartRequest{Trigger: model.TriggerManual})
+
+		require.NoError(t, err)
+		assert.Equal(t, []int{protocol.MinSelfUpdateVersion}, h.mins)
+		require.Len(t, h.starts, 1)
+		assert.False(t, h.starts[0].start.Self)
+	})
 	t.Run("a service that is not the agent's own is not marked", func(t *testing.T) {
 		st := &fakeStore{services: map[int64]model.Service{1: composeSvc}, jobs: map[int64]model.Job{}}
 		h := &fakeHub{route: ok}