fix: validate module schema on deployment (#747)

The previous change resulted in relative refs within a module not being
written back to the schema before committing to the DB.

backend/controller/controller.go

@@ -693,7 +693,8 @@ func (s *Service) CreateDeployment(ctx context.Context, req *connect.Request[ftl
 		logger.Errorf(err, "Invalid module schema")
 		return nil, fmt.Errorf("%s: %w", "invalid module schema", err)
 	}
-	if err := s.validateWholeSchema(ctx, module); err != nil {
+	module, err = s.validateWholeSchema(ctx, module)
+	if err != nil {
 		logger.Errorf(err, "Invalid module schema")
 		return nil, fmt.Errorf("%s: %w", "invalid module schema", err)
 	}
@@ -710,16 +711,19 @@ func (s *Service) CreateDeployment(ctx context.Context, req *connect.Request[ftl
 }
 
 // Load schemas for existing modules, combine with our new one, and validate as a whole.
-func (s *Service) validateWholeSchema(ctx context.Context, module *schema.Module) error {
+func (s *Service) validateWholeSchema(ctx context.Context, module *schema.Module) (*schema.Module, error) {
 	existingModules, err := s.dal.GetActiveDeploymentSchemas(ctx)
 	if err != nil {
-		return fmt.Errorf("%s: %w", "could not get existing schemas", err)
+		return nil, fmt.Errorf("%s: %w", "could not get existing schemas", err)
 	}
 	schemaMap := ftlmaps.FromSlice(existingModules, func(el *schema.Module) (string, *schema.Module) { return el.Name, el })
 	schemaMap[module.Name] = module
 	fullSchema := &schema.Schema{Modules: maps.Values(schemaMap)}
-	_, err = schema.Validate(fullSchema)
-	return err
+	schema, err := schema.Validate(fullSchema)
+	if err != nil {
+		return nil, fmt.Errorf("%s: %w", "invalid schema", err)
+	}
+	return schema.Module(module.Name).MustGet(), nil
 }
 
 func (s *Service) getDeployment(ctx context.Context, name string) (*model.Deployment, error) {
@@ -1053,11 +1057,11 @@ func (s *Service) getActiveSchema(ctx context.Context) (*schema.Schema, error) {
 	if err != nil {
 		return nil, err
 	}
-	return &schema.Schema{
+	return schema.Validate(&schema.Schema{
 		Modules: slices.Map(deployments, func(d dal.Deployment) *schema.Module {
 			return d.Schema
 		}),
-	}, nil
+	})
 }
 
 // Copied from the Apache-licensed connect-go source.

backend/schema/schema.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/alecthomas/participle/v2"
 	"github.com/alecthomas/participle/v2/lexer"
+	"github.com/alecthomas/types"
 	"golang.org/x/exp/maps"
 	"google.golang.org/protobuf/proto"
 )
@@ -312,6 +313,16 @@ type Schema struct {
 	Modules []*Module `parser:"@@*" protobuf:"2"`
 }
 
+// Module returns the named module if it exists.
+func (s *Schema) Module(name string) types.Option[*Module] {
+	for _, module := range s.Modules {
+		if module.Name == name {
+			return types.Some(module)
+		}
+	}
+	return types.None[*Module]()
+}
+
 func (s *Schema) DataMap() map[DataRef]*Data {
 	dataTypes := map[DataRef]*Data{}
 	for _, module := range s.Modules {

backend/schema/validate.go

@@ -73,10 +73,12 @@ func Validate(schema *Schema) (*Schema, error) {
 	dataRefs := []*DataRef{}
 	merr := []error{}
 	ingress := map[string]*Verb{}
+
 	// Inject builtins.
 	builtins := Builtins()
 	schema.Modules = slices.DeleteFunc(schema.Modules, func(m *Module) bool { return m.Name == builtins.Name })
 	schema.Modules = append([]*Module{builtins}, schema.Modules...)
+
 	// Map from reference to the module it is defined in.
 	localModule := map[*Ref]*Module{}