Merge pull request juju#18393 from ycliuhw/model-status-service-layer

juju#18393

This PR introduces the a new service method in the `model` domain package for the model status feature: 

- Status - the model status will be computed in the service layer and returned as:
 - `destroying` if the model is being destroyed;
 - `suspended` if the model has an invalid cloud credential;
 - `busy` if the model is being migrated;
 - in other cases, it returns `available`;

Drive-by: 
- after discussion, we decided to compute all model statuses, so the model status DDL has been removed.

## Checklist

- [x] Code style: imports ordered, good names, simple structure, etc
- [x] Comments saying why design decisions were made
- [x] Go unit tests, with comments saying what you're testing
- [ ] ~[Integration tests](https://github.com/juju/juju/tree/main/tests), with comments saying what you're testing~
- [ ] ~[doc.go](https://discourse.charmhub.io/t/readme-in-packages/451) added or updated in changed packages~

## QA steps

unit tests.

## Documentation changes

No

## Links

**Jira card:** [JUJU-7099](https://warthogs.atlassian.net/browse/JUJU-7099)



[JUJU-7099]: https://warthogs.atlassian.net/browse/JUJU-7099?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

domain/model/service/modelservice.go

@@ -6,8 +6,12 @@ package service
 import (
 	"context"
 
+	"github.com/juju/clock"
+
 	coremodel "github.com/juju/juju/core/model"
+	corestatus "github.com/juju/juju/core/status"
 	"github.com/juju/juju/domain/model"
+	"github.com/juju/juju/internal/errors"
 	"github.com/juju/juju/internal/uuid"
 )
 
@@ -24,37 +28,43 @@ type ModelState interface {
 	Model(context.Context) (coremodel.ReadOnlyModel, error)
 }
 
-// ModelGetterState represents the state required for reading all model
-// information.
-type ModelGetterState interface {
+// ControllerState is the controller state required by this service. This is the
+// controller database, not the model state.
+type ControllerState interface {
+	// GetModel returns the model with the given UUID.
 	GetModel(context.Context, coremodel.UUID) (coremodel.Model, error)
+
+	// GetModelState returns the model state for the given model.
+	// It returns [modelerrors.NotFound] if the model does not exist for the given UUID.
+	GetModelState(context.Context, coremodel.UUID) (model.ModelState, error)
 }
 
 // ModelService defines a service for interacting with the underlying model
 // state, as opposed to the controller state.
 type ModelService struct {
-	modelID       coremodel.UUID
-	modelGetterSt ModelGetterState
-	st            ModelState
+	clock        clock.Clock
+	modelID      coremodel.UUID
+	controllerSt ControllerState
+	modelSt      ModelState
 }
 
 // NewModelService returns a new Service for interacting with a models state.
 func NewModelService(
 	modelID coremodel.UUID,
-	modelGetterSt ModelGetterState,
-	st ModelState,
+	controllerSt ControllerState,
+	modelSt ModelState,
 ) *ModelService {
 	return &ModelService{
-		modelID:       modelID,
-		modelGetterSt: modelGetterSt,
-		st:            st,
+		modelID:      modelID,
+		controllerSt: controllerSt,
+		modelSt:      modelSt,
 	}
 }
 
 // GetModelInfo returns the readonly model information for the model in
 // question.
 func (s *ModelService) GetModelInfo(ctx context.Context) (coremodel.ReadOnlyModel, error) {
-	return s.st.Model(ctx)
+	return s.modelSt.Model(ctx)
 }
 
 // CreateModel is responsible for creating a new model within the model
@@ -66,7 +76,7 @@ func (s *ModelService) CreateModel(
 	ctx context.Context,
 	controllerUUID uuid.UUID,
 ) error {
-	m, err := s.modelGetterSt.GetModel(ctx, s.modelID)
+	m, err := s.controllerSt.GetModel(ctx, s.modelID)
 	if err != nil {
 		return err
 	}
@@ -84,7 +94,7 @@ func (s *ModelService) CreateModel(
 		CredentialName:  m.Credential.Name,
 	}
 
-	return s.st.Create(ctx, args)
+	return s.modelSt.Create(ctx, args)
 }
 
 // DeleteModel is responsible for removing a model from the system.
@@ -94,5 +104,45 @@ func (s *ModelService) CreateModel(
 func (s *ModelService) DeleteModel(
 	ctx context.Context,
 ) error {
-	return s.st.Delete(ctx, s.modelID)
+	return s.modelSt.Delete(ctx, s.modelID)
+}
+
+// Status returns the current status of the model.
+//
+// The following error types can be expected to be returned:
+// - [modelerrors.NotFound]: When the model does not exist.
+func (s *ModelService) Status(ctx context.Context) (model.StatusInfo, error) {
+	modelState, err := s.controllerSt.GetModelState(ctx, s.modelID)
+	if err != nil {
+		return model.StatusInfo{}, errors.Capture(err)
+	}
+
+	now := s.clock.Now()
+	if modelState.HasInvalidCloudCredential {
+		return model.StatusInfo{
+			Status:  corestatus.Suspended,
+			Message: "suspended since cloud credential is not valid",
+			Reason:  modelState.InvalidCloudCredentialReason,
+			Since:   now,
+		}, nil
+	}
+	if modelState.Destroying {
+		return model.StatusInfo{
+			Status:  corestatus.Destroying,
+			Message: "the model is being destroyed",
+			Since:   now,
+		}, nil
+	}
+	if modelState.Migrating {
+		return model.StatusInfo{
+			Status:  corestatus.Busy,
+			Message: "the model is being migrated",
+			Since:   now,
+		}, nil
+	}
+
+	return model.StatusInfo{
+		Status: corestatus.Available,
+		Since:  now,
+	}, nil
 }

domain/model/service/modelservice_test.go

@@ -5,14 +5,17 @@ package service
 
 import (
 	"context"
+	"time"
 
+	"github.com/juju/clock/testclock"
 	"github.com/juju/testing"
 	jc "github.com/juju/testing/checkers"
 	gc "gopkg.in/check.v1"
 
 	corecredential "github.com/juju/juju/core/credential"
 	coremodel "github.com/juju/juju/core/model"
 	modeltesting "github.com/juju/juju/core/model/testing"
+	corestatus "github.com/juju/juju/core/status"
 	"github.com/juju/juju/domain/model"
 	modelerrors "github.com/juju/juju/domain/model/errors"
 	"github.com/juju/juju/internal/uuid"
@@ -21,6 +24,8 @@ import (
 type dummyModelState struct {
 	models map[coremodel.UUID]model.ReadOnlyModelCreationArgs
 	setID  coremodel.UUID
+
+	modelState map[coremodel.UUID]model.ModelState
 }
 
 func (d *dummyModelState) Create(ctx context.Context, args model.ReadOnlyModelCreationArgs) error {
@@ -80,6 +85,14 @@ func (d *dummyModelState) Delete(ctx context.Context, modelUUID coremodel.UUID)
 	return nil
 }
 
+func (d *dummyModelState) GetModelState(_ context.Context, modelUUID coremodel.UUID) (model.ModelState, error) {
+	mState, ok := d.modelState[modelUUID]
+	if !ok {
+		return model.ModelState{}, modelerrors.NotFound
+	}
+	return mState, nil
+}
+
 type modelServiceSuite struct {
 	testing.IsolationSuite
 
@@ -91,7 +104,8 @@ var _ = gc.Suite(&modelServiceSuite{})
 
 func (s *modelServiceSuite) SetUpTest(c *gc.C) {
 	s.state = &dummyModelState{
-		models: map[coremodel.UUID]model.ReadOnlyModelCreationArgs{},
+		models:     map[coremodel.UUID]model.ReadOnlyModelCreationArgs{},
+		modelState: map[coremodel.UUID]model.ModelState{},
 	}
 
 	s.controllerUUID = uuid.MustNewUUID()
@@ -146,3 +160,94 @@ func (s *modelServiceSuite) TestModelDeletion(c *gc.C) {
 	_, exists := s.state.models[id]
 	c.Assert(exists, jc.IsFalse)
 }
+
+func (s *modelServiceSuite) TestStatusSuspended(c *gc.C) {
+	id := modeltesting.GenModelUUID(c)
+	svc := NewModelService(id, s.state, s.state)
+	svc.clock = testclock.NewClock(time.Time{})
+
+	s.state.setID = id
+	s.state.modelState[id] = model.ModelState{
+		HasInvalidCloudCredential:    true,
+		InvalidCloudCredentialReason: "invalid credential",
+	}
+
+	now := svc.clock.Now()
+	status, err := svc.Status(context.Background())
+	c.Assert(err, jc.ErrorIsNil)
+	c.Assert(status.Status, gc.Equals, corestatus.Suspended)
+	c.Assert(status.Message, gc.Equals, "suspended since cloud credential is not valid")
+	c.Assert(status.Reason, gc.Equals, "invalid credential")
+	c.Assert(status.Since, jc.Almost, now)
+}
+
+func (s *modelServiceSuite) TestStatusDestroying(c *gc.C) {
+	id := modeltesting.GenModelUUID(c)
+	svc := &ModelService{
+		clock:        testclock.NewClock(time.Time{}),
+		modelID:      id,
+		controllerSt: s.state,
+		modelSt:      s.state,
+	}
+
+	s.state.setID = id
+	s.state.modelState[id] = model.ModelState{
+		Destroying: true,
+	}
+
+	now := svc.clock.Now()
+	status, err := svc.Status(context.Background())
+	c.Assert(err, jc.ErrorIsNil)
+	c.Assert(status.Status, gc.Equals, corestatus.Destroying)
+	c.Assert(status.Message, gc.Equals, "the model is being destroyed")
+	c.Assert(status.Since, jc.Almost, now)
+}
+
+func (s *modelServiceSuite) TestStatusBusy(c *gc.C) {
+	id := modeltesting.GenModelUUID(c)
+	svc := &ModelService{
+		clock:        testclock.NewClock(time.Time{}),
+		modelID:      id,
+		controllerSt: s.state,
+		modelSt:      s.state,
+	}
+
+	s.state.setID = id
+	s.state.modelState[id] = model.ModelState{
+		Migrating: true,
+	}
+
+	now := svc.clock.Now()
+	status, err := svc.Status(context.Background())
+	c.Assert(err, jc.ErrorIsNil)
+	c.Assert(status.Status, gc.Equals, corestatus.Busy)
+	c.Assert(status.Message, gc.Equals, "the model is being migrated")
+	c.Assert(status.Since, jc.Almost, now)
+}
+
+func (s *modelServiceSuite) TestStatus(c *gc.C) {
+	id := modeltesting.GenModelUUID(c)
+	svc := &ModelService{
+		clock:        testclock.NewClock(time.Time{}),
+		modelID:      id,
+		controllerSt: s.state,
+		modelSt:      s.state,
+	}
+
+	s.state.setID = id
+	s.state.modelState[id] = model.ModelState{}
+
+	now := svc.clock.Now()
+	status, err := svc.Status(context.Background())
+	c.Assert(err, jc.ErrorIsNil)
+	c.Assert(status.Status, gc.Equals, corestatus.Available)
+	c.Assert(status.Since, jc.Almost, now)
+}
+
+func (s *modelServiceSuite) TestStatusFaildModelNotFound(c *gc.C) {
+	id := modeltesting.GenModelUUID(c)
+	svc := NewModelService(id, s.state, s.state)
+
+	_, err := svc.Status(context.Background())
+	c.Assert(err, jc.ErrorIs, modelerrors.NotFound)
+}

domain/model/state/state.go → domain/model/state/controllerstate.go

@@ -1680,3 +1680,9 @@ AND    ot.type = $dbPermission.object_type
 	}
 	return nil
 }
+
+// GetModelState returns the model state for the given model UUID.
+func (s *State) GetModelState(context.Context, coremodel.UUID) (model.ModelState, error) {
+	// TODO: Implement GetModelState
+	return model.ModelState{}, nil
+}

domain/model/types.go

@@ -5,12 +5,14 @@ package model
 
 import (
 	"fmt"
+	"time"
 
 	"github.com/juju/errors"
 	"github.com/juju/version/v2"
 
 	"github.com/juju/juju/core/credential"
 	coremodel "github.com/juju/juju/core/model"
+	corestatus "github.com/juju/juju/core/status"
 	"github.com/juju/juju/core/user"
 	"github.com/juju/juju/internal/uuid"
 )
@@ -177,3 +179,27 @@ func WithDeleteDB() DeleteModelOption {
 		o.deleteDB = true
 	}
 }
+
+// StatusInfo holds a Status and associated information of a model.
+type StatusInfo struct {
+	// Status is the current status of the model.
+	Status corestatus.Status
+	// Message is a human-readable message that describes the current status of the model.
+	Message string
+	// Reason is a human-readable message that describes the reason for the current status of the model.
+	Reason string
+	// Since is the time when the model entered the current status.
+	Since time.Time
+}
+
+// ModelState describes the state of a model.
+type ModelState struct {
+	// Destroying is a boolean value that indicates if the model is being destroyed.
+	Destroying bool
+	// Migrating is a boolean value that indicates if the model is being migrated.
+	Migrating bool
+	// HasInvalidCloudCredential is a boolean value that indicates if the model's cloud credential is invalid.
+	HasInvalidCloudCredential bool
+	// InvalidCloudCredentialReason is a string that describes the reason for the model's cloud credential being invalid.
+	InvalidCloudCredentialReason string
+}

domain/schema/schema_test.go

@@ -296,10 +296,6 @@ func (s *schemaSuite) TestModelTables(c *gc.C) {
 		// Model config
 		"model_config",
 
-		// Model status
-		"model_status",
-		"model_status_value",
-
 		// Object store metadata
 		"object_store_metadata",
 		"object_store_metadata_path",