sdk/instancesdk: optionally delete instance's data volumes during ins…

…tance Delete()

and update gRPC API to migrate this feature.

resolves #1069.

protobuf/api/instance.proto

@@ -38,6 +38,7 @@ message CreateInstanceResponse {
 
 message DeleteInstanceRequest {
   string hash = 1;      // Instance hash
+  bool deleteData = 2;   // if enabled, any persistent data (volumes) that belongs to instance and its dependencies will also be deleted.
 }
 
 message DeleteInstanceResponse {

sdk/instance/instance.go

@@ -119,14 +119,24 @@ func (i *Instance) GetAllByService(serviceHash string) ([]*instance.Instance, er
 	return i.instanceDB.GetAllByService(serviceHash)
 }
 
-// Delete an instance
-func (i *Instance) Delete(hash string) error {
+// Delete deletes an instance.
+// if deleteData is enabled, any persistent data that belongs to
+// the instance and to its dependencies will also be deleted.
+func (i *Instance) Delete(hash string, deleteData bool) error {
 	inst, err := i.instanceDB.Get(hash)
 	if err != nil {
 		return err
 	}
 	if err := i.stop(inst); err != nil {
 		return err
 	}
+	// delete volumes first before the instance. this way if
+	// deleting volumes fails, process can be retried by the user again
+	// because instance still will be in the db.
+	if deleteData {
+		if err := i.deleteData(inst); err != nil {
+			return err
+		}
+	}
 	return i.instanceDB.Delete(hash)
 }

sdk/instance/volume.go

@@ -0,0 +1,43 @@
+package instancesdk
+
+import (
+	"sync"
+
+	"github.com/docker/docker/client"
+	"github.com/mesg-foundation/core/instance"
+	"github.com/mesg-foundation/core/x/xerrors"
+)
+
+// deleteData deletes the data volumes of instance and its dependencies.
+// TODO: right now deleteData() is not compatible to work with multiple instances of same
+// service since extractVolumes() accepts service, not instance. same applies in the start
+// api as well. make it work with multiple instances.
+func (i *Instance) deleteData(inst *instance.Instance) error {
+	s, err := i.serviceDB.Get(inst.ServiceHash)
+	if err != nil {
+		return err
+	}
+	var (
+		wg   sync.WaitGroup
+		errs xerrors.SyncErrors
+	)
+	for _, d := range append(s.Dependencies, s.Configuration) {
+		// Service.Configuration can be nil so, here is a check for it.
+		if d == nil {
+			continue
+		}
+		for _, volume := range extractVolumes(s, d) {
+			wg.Add(1)
+			go func(source string) {
+				defer wg.Done()
+				// if service is never started before, data volume won't be created and Docker Engine
+				// will return with the not found error. therefore, we can safely ignore it.
+				if err := i.container.DeleteVolume(source); err != nil && !client.IsErrNotFound(err) {
+					errs.Append(err)
+				}
+			}(volume.Source)
+		}
+	}
+	wg.Wait()
+	return errs.ErrorOrNil()
+}

server/grpc/instance.go

@@ -49,7 +49,7 @@ func (s *InstanceServer) Get(ctx context.Context, request *protobuf_api.GetInsta
 
 // Delete an instance
 func (s *InstanceServer) Delete(ctx context.Context, request *protobuf_api.DeleteInstanceRequest) (*protobuf_api.DeleteInstanceResponse, error) {
-	err := s.sdk.Instance.Delete(request.Hash)
+	err := s.sdk.Instance.Delete(request.Hash, request.DeleteData)
 	if err != nil {
 		return nil, err
 	}