Merge pull request juju#18092 from wallyworld/cleanup-unit-insertion

juju#18092

In application state, the logic for inserting and updating a unit was intertwined after code for register caas unit was added some time after the initial vm add unit code.
They are now separate operations. The branching logic in state has been moved up a layer.

## QA steps

juju bootstrap microk8s
juju deploy snappass-test

## Links

**Jira card:** [JUJU-6059](https://warthogs.atlassian.net/browse/JUJU-6059)



[JUJU-6059]: https://warthogs.atlassian.net/browse/JUJU-6059?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

domain/application/errors/errors.go

@@ -39,14 +39,14 @@ const (
 	// does not exist.
 	UnitNotFound = errors.ConstError("unit not found")
 
-	// UnitNotAssigned describes an error that occurs when the unit being operated on
-	// is not assigned.
-	UnitNotAssigned = errors.ConstError("unit not assigned")
-
 	// UnitAlreadyExists describes an error that occurs when the
 	// unit being created already exists.
 	UnitAlreadyExists = errors.ConstError("unit already exists")
 
+	// UnitNotAssigned describes an error that occurs when the unit being operated on
+	// is not assigned.
+	UnitNotAssigned = errors.ConstError("unit not assigned")
+
 	// UnitHasSubordinates describes an error that occurs when trying to set a unit's life
 	// to Dead but it still has subordinates.
 	UnitHasSubordinates = errors.ConstError("unit has subordinates")

domain/application/service/application.go

@@ -49,10 +49,14 @@ type AtomicApplicationState interface {
 	// application is not found.
 	GetApplicationID(ctx domain.AtomicContext, name string) (coreapplication.ID, error)
 
-	// UpsertUnit creates or updates the specified application unit, returning
-	// an error satisfying [applicationerrors.ApplicationNotFoundError] if the
-	// application doesn't exist.
-	UpsertUnit(domain.AtomicContext, coreapplication.ID, application.UpsertUnitArg) error
+	// InsertUnit insert the specified application unit, returning an error
+	// satisfying [applicationerrors.UnitAlreadyExists]
+	// if the unit exists.
+	InsertUnit(domain.AtomicContext, coreapplication.ID, application.UpsertUnitArg) error
+
+	// UpdateUnit updates the specified application unit, returning an error
+	// satisfying [applicationerrors.UnitNotFoundError] if the unit doesn't exist.
+	UpdateUnit(domain.AtomicContext, coreapplication.ID, application.UpsertUnitArg) error
 
 	// GetApplicationLife looks up the life of the specified application, returning an error
 	// satisfying [applicationerrors.ApplicationNotFoundError] if the application is not found.
@@ -298,11 +302,13 @@ func makeUpsertUnitArgs(in AddUnitArg) application.UpsertUnitArg {
 			Ports:      in.CloudContainer.Ports,
 		}
 		if in.CloudContainer.Address != nil {
+			// TODO(units) - handle the in.CloudContainer.Address space ID
+			// For k8s we'll initially create a /32 subnet off the container address
+			// and add that to the default space.
 			result.CloudContainer.Address = &application.Address{
 				Value:       in.CloudContainer.Address.Value,
 				AddressType: string(in.CloudContainer.Address.AddressType()),
 				Scope:       string(in.CloudContainer.Address.Scope),
-				SpaceID:     in.CloudContainer.Address.SpaceID,
 				Origin:      string(network.OriginProvider),
 			}
 			if in.CloudContainer.AddressOrigin != nil {
@@ -516,8 +522,6 @@ func (s *ApplicationService) RegisterCAASUnit(ctx context.Context, appName strin
 	}
 	if args.Address != nil {
 		addr := network.NewSpaceAddress(*args.Address, network.WithScope(network.ScopeMachineLocal))
-		// k8s doesn't support spaces yet.
-		addr.SpaceID = network.AlphaSpaceId
 		p.CloudContainer.Address = &addr
 		origin := network.OriginProvider
 		p.CloudContainer.AddressOrigin = &origin
@@ -537,7 +541,7 @@ func (s *ApplicationService) RegisterCAASUnit(ctx context.Context, appName strin
 		if unitLife == life.Dead {
 			return fmt.Errorf("dead unit %q already exists%w", args.UnitName, errors.Hide(applicationerrors.UnitAlreadyExists))
 		}
-		return s.st.UpsertUnit(ctx, appID, unitArg)
+		return s.st.UpdateUnit(ctx, appID, unitArg)
 	})
 	return errors.Annotatef(err, "saving caas unit %q", args.UnitName)
 }
@@ -553,7 +557,7 @@ func (s *ApplicationService) insertCAASUnit(
 		(appScale.Scaling && orderedID >= appScale.ScaleTarget) {
 		return fmt.Errorf("unrequired unit %s is not assigned%w", *args.UnitName, errors.Hide(applicationerrors.UnitNotAssigned))
 	}
-	return s.st.UpsertUnit(ctx, appID, args)
+	return s.st.InsertUnit(ctx, appID, args)
 }
 
 // DeleteApplication deletes the specified application, returning an error