RBD/RADOS volume management should be handled by libvirt

[wido]

ISSUE TYPE

• Enhancement Request

COMPONENT NAME

CloudStack Agent

CLOUDSTACK VERSION

all

SUMMARY

The CloudStack Agent uses com.ceph.rados.* for many operations as when implementing the RBD storage pool support not all features were supported by Libvirt.

For example:

cloudstack/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/storage/LibvirtStorageAdaptor.java

Line 913 in 1a304cc

IoCTX io = r.ioCtxCreate(pool.getSourceDir());

                IoCTX io = r.ioCtxCreate(pool.getSourceDir());
                Rbd rbd = new Rbd(io);
                RbdImage image = rbd.open(uuid);
                s_logger.debug("Fetching list of snapshots of RBD image " + pool.getSourceDir() + "/" + uuid);
                List<RbdSnapInfo> snaps = image.snapList();
                try {
                    for (RbdSnapInfo snap : snaps) {
                        if (image.snapIsProtected(snap.name)) {
                            s_logger.debug("Unprotecting snapshot " + pool.getSourceDir() + "/" + uuid + "@" + snap.name);
                            image.snapUnprotect(snap.name);
                        } else {
                            s_logger.debug("Snapshot " + pool.getSourceDir() + "/" + uuid + "@" + snap.name + " is not protected.");
                        }
                        s_logger.debug("Removing snapshot " + pool.getSourceDir() + "/" + uuid + "@" + snap.name);
                        image.snapRemove(snap.name);
                    }
                    s_logger.info("Successfully unprotected and removed any remaining snapshots (" + snaps.size() + ") of "
                        + pool.getSourceDir() + "/" + uuid + " Continuing to remove the RBD image");
                } catch (RbdException e) {
                    s_logger.error("Failed to remove snapshot with exception: " + e.toString() +
                        ", RBD error: " + ErrorCode.getErrorMessage(e.getReturnValue()));
                    throw new CloudRuntimeException(e.toString() + " - " + ErrorCode.getErrorMessage(e.getReturnValue()));
                } finally {
                    s_logger.debug("Closing image and destroying context");
                    rbd.close(image);
                    r.ioCtxDestroy(io);
                }
            } catch (RadosException e) {
                s_logger.error("Failed to remove snapshot with exception: " + e.toString() +
                    ", RBD error: " + ErrorCode.getErrorMessage(e.getReturnValue()));
                throw new CloudRuntimeException(e.toString() + " - " + ErrorCode.getErrorMessage(e.getReturnValue()));
            } catch (RbdException e) {
                s_logger.error("Failed to remove snapshot with exception: " + e.toString() +
                    ", RBD error: " + ErrorCode.getErrorMessage(e.getReturnValue()));
                throw new CloudRuntimeException(e.toString() + " - " + ErrorCode.getErrorMessage(e.getReturnValue()));
            }
        }

Here the CloudStack agent purges any RBD snapshots as they need to be removed prior to removing the RBD image.

Modern libvirt can do this for you (pseudo code):

StorageVol.delete(VIR_STORAGE_VOL_DELETE_WITH_SNAPSHOTS)

This removes a lot of lines of code from CloudStack and leverages what libvirt can do for us.

This is just one example, but there are other places where the CloudStack agent uses the librados Java bindings directly while those things can be handled by libvirt.