* Refactoring

* Fix issue that causes a new image store to be created at every start of ucloud-api.
* VM Migration API call now takes hostname instead of host key.
* StorageHandler Classes are introduced. They transparently handles things related to importing of image, make vm out of image, resize vm image, delete vm image etc.
* Loggers added to __init__.py of every ucloud component's subpackage.
* Non-Trivial Timeout Events are no longer logged.
* Fix issue that prevents removal of stopped VMs (i.e VMs that are successfully migrated).
* Improved unit handling added. e.g MB, Mb, mB, mb are all Mega Bytes.
* VM migration is now possible on IPv6 host.
* Destination VM (receiving side of migration of a vm) now correctly expects incoming data on free ephemeral port.
* Traceback is no longer output to screen, instead it goes to log file.
* All sanity checks are put into a single file. These checks are run by ucloud.py before running any of ucloud component.

api/helper.py

@@ -22,7 +22,7 @@ def check_otp(name, realm, token):
     except binascii.Error:
         return 400
 
-    response = requests.get(
+    response = requests.post(
         "{OTP_SERVER}{OTP_VERIFY_ENDPOINT}".format(
             OTP_SERVER=env_vars.get("OTP_SERVER", ""),
             OTP_VERIFY_ENDPOINT=env_vars.get("OTP_VERIFY_ENDPOINT", "verify"),

api/main.py

@@ -1,16 +1,16 @@
 import json
-import os
 import subprocess
-from uuid import uuid4
-
 import pynetbox
+
+from uuid import uuid4
+from os.path import join as join_path
+
 from flask import Flask, request
 from flask_restful import Resource, Api
 
 from common import counters
 from common.request import RequestEntry, RequestType
-from common.vm import VMStatus
-from config import (etcd_client, request_pool, vm_pool, host_pool, env_vars)
+from config import (etcd_client, request_pool, vm_pool, host_pool, env_vars, image_storage_handler)
 from . import schemas
 from .helper import generate_mac, mac2ipv6
 from api import logger
@@ -20,13 +20,15 @@ api = Api(app)
 
 
 class CreateVM(Resource):
+    """API Request to Handle Creation of VM"""
+
     @staticmethod
     def post():
         data = request.json
         validator = schemas.CreateVMSchema(data)
         if validator.is_valid():
             vm_uuid = uuid4().hex
-            vm_key = os.path.join(env_vars.get("VM_PREFIX"), vm_uuid)
+            vm_key = join_path(env_vars.get("VM_PREFIX"), vm_uuid)
             specs = {
                 "cpu": validator.specs["cpu"],
                 "ram": validator.specs["ram"],
@@ -67,14 +69,14 @@ class VmStatus(Resource):
         validator = schemas.VMStatusSchema(data)
         if validator.is_valid():
             vm = vm_pool.get(
-                os.path.join(env_vars.get("VM_PREFIX"), data["uuid"])
+                join_path(env_vars.get("VM_PREFIX"), data["uuid"])
             )
             vm_value = vm.value.copy()
             vm_value["ip"] = []
             for network_and_mac in vm.network:
                 network_name, mac = network_and_mac
                 network = etcd_client.get(
-                    os.path.join(
+                    join_path(
                         env_vars.get("NETWORK_PREFIX"),
                         data["name"],
                         network_name,
@@ -96,7 +98,7 @@ class CreateImage(Resource):
         validator = schemas.CreateImageSchema(data)
         if validator.is_valid():
             file_entry = etcd_client.get(
-                os.path.join(env_vars.get("FILE_PREFIX"), data["uuid"])
+                join_path(env_vars.get("FILE_PREFIX"), data["uuid"])
             )
             file_entry_value = json.loads(file_entry.value)
 
@@ -109,7 +111,7 @@ class CreateImage(Resource):
                 "visibility": "public",
             }
             etcd_client.put(
-                os.path.join(env_vars.get("IMAGE_PREFIX"), data["uuid"]),
+                join_path(env_vars.get("IMAGE_PREFIX"), data["uuid"]),
                 json.dumps(image_entry_json),
             )
 
@@ -123,8 +125,9 @@ class ListPublicImages(Resource):
         images = etcd_client.get_prefix(
             env_vars.get("IMAGE_PREFIX"), value_in_json=True
         )
-        r = {}
-        r["images"] = []
+        r = {
+            "images": []
+        }
         for image in images:
             image_key = "{}:{}".format(
                 image.value["store_name"], image.value["name"]
@@ -143,46 +146,22 @@ class VMAction(Resource):
 
         if validator.is_valid():
             vm_entry = vm_pool.get(
-                os.path.join(env_vars.get("VM_PREFIX"), data["uuid"])
+                join_path(env_vars.get("VM_PREFIX"), data["uuid"])
             )
             action = data["action"]
 
             if action == "start":
-                vm_entry.status = VMStatus.requested_start
-                vm_pool.put(vm_entry)
                 action = "schedule"
 
             if action == "delete" and vm_entry.hostname == "":
-                try:
-                    path_without_protocol = vm_entry.path[
-                                            vm_entry.path.find(":") + 1:
-                                            ]
-
-                    if env_vars.get("WITHOUT_CEPH"):
-                        command_to_delete = [
-                            "rm",
-                            "-rf",
-                            os.path.join("/var/vm", vm_entry.uuid),
-                        ]
-                    else:
-                        command_to_delete = [
-                            "rbd",
-                            "rm",
-                            path_without_protocol,
-                        ]
-
-                    subprocess.check_output(
-                        command_to_delete, stderr=subprocess.PIPE
-                    )
-                except subprocess.CalledProcessError as e:
-                    if "No such file" in e.stderr.decode("utf-8"):
+                if image_storage_handler.is_vm_image_exists(vm_entry.uuid):
+                    r_status = image_storage_handler.delete_vm_image(vm_entry.uuid)
+                    if r_status:
                         etcd_client.client.delete(vm_entry.key)
                         return {"message": "VM successfully deleted"}
                     else:
-                        logger.exception(e)
-                        return {
-                            "message": "Some error occurred while deleting VM"
-                        }
+                        logger.error("Some Error Occurred while deleting VM")
+                        return {"message": "VM deletion unsuccessfull"}
                 else:
                     etcd_client.client.delete(vm_entry.key)
                     return {"message": "VM successfully deleted"}
@@ -211,8 +190,8 @@ class VMMigration(Resource):
             r = RequestEntry.from_scratch(
                 type=RequestType.ScheduleVM,
                 uuid=vm.uuid,
-                destination=os.path.join(
-                    env_vars.get("HOST_PREFIX"), data["destination"]
+                destination=join_path(
+                    env_vars.get("HOST_PREFIX"), validator.destination.value
                 ),
                 migration=True,
                 request_prefix=env_vars.get("REQUEST_PREFIX")
@@ -289,7 +268,7 @@ class CreateHost(Resource):
         data = request.json
         validator = schemas.CreateHostSchema(data)
         if validator.is_valid():
-            host_key = os.path.join(env_vars.get("HOST_PREFIX"), uuid4().hex)
+            host_key = join_path(env_vars.get("HOST_PREFIX"), uuid4().hex)
             host_entry = {
                 "specs": data["specs"],
                 "hostname": data["hostname"],
@@ -327,7 +306,7 @@ class GetSSHKeys(Resource):
             if not validator.key_name.value:
 
                 # {user_prefix}/{realm}/{name}/key/
-                etcd_key = os.path.join(
+                etcd_key = join_path(
                     env_vars.get('USER_PREFIX'),
                     data["realm"],
                     data["name"],
@@ -344,7 +323,7 @@ class GetSSHKeys(Resource):
             else:
 
                 # {user_prefix}/{realm}/{name}/key/{key_name}
-                etcd_key = os.path.join(
+                etcd_key = join_path(
                     env_vars.get('USER_PREFIX'),
                     data["realm"],
                     data["name"],
@@ -373,7 +352,7 @@ class AddSSHKey(Resource):
         if validator.is_valid():
 
             # {user_prefix}/{realm}/{name}/key/{key_name}
-            etcd_key = os.path.join(
+            etcd_key = join_path(
                 env_vars.get("USER_PREFIX"),
                 data["realm"],
                 data["name"],
@@ -403,7 +382,7 @@ class RemoveSSHKey(Resource):
         if validator.is_valid():
 
             # {user_prefix}/{realm}/{name}/key/{key_name}
-            etcd_key = os.path.join(
+            etcd_key = join_path(
                 env_vars.get("USER_PREFIX"),
                 data["realm"],
                 data["name"],
@@ -462,7 +441,7 @@ class CreateNetwork(Resource):
             else:
                 network_entry["ipv6"] = "fd00::/64"
 
-            network_key = os.path.join(
+            network_key = join_path(
                 env_vars.get("NETWORK_PREFIX"),
                 data["name"],
                 data["network_name"],
@@ -480,7 +459,7 @@ class ListUserNetwork(Resource):
         validator = schemas.OTPSchema(data)
 
         if validator.is_valid():
-            prefix = os.path.join(
+            prefix = join_path(
                 env_vars.get("NETWORK_PREFIX"), data["name"]
             )
             networks = etcd_client.get_prefix(prefix, value_in_json=True)
@@ -517,15 +496,17 @@ api.add_resource(CreateNetwork, "/network/create")
 
 
 def main():
-    data = {
-        "is_public": True,
-        "type": "ceph",
-        "name": "images",
-        "description": "first ever public image-store",
-        "attributes": {"list": [], "key": [], "pool": "images"},
-    }
+    image_stores = list(etcd_client.get_prefix(env_vars.get('IMAGE_STORE_PREFIX'), value_in_json=True))
+    if len(image_stores) == 0:
+        data = {
+            "is_public": True,
+            "type": "ceph",
+            "name": "images",
+            "description": "first ever public image-store",
+            "attributes": {"list": [], "key": [], "pool": "images"},
+        }
 
-    etcd_client.put(os.path.join(env_vars.get('IMAGE_STORE_PREFIX'), uuid4().hex), json.dumps(data))
+        etcd_client.put(join_path(env_vars.get('IMAGE_STORE_PREFIX'), uuid4().hex), json.dumps(data))
 
     app.run(host="::", debug=True)
 

api/schemas.py

@@ -381,12 +381,14 @@ class VmMigrationSchema(OTPSchema):
         super().__init__(data=data, fields=fields)
 
     def destination_validation(self):
-        host_key = self.destination.value
-        host = host_pool.get(host_key)
+        hostname = self.destination.value
+        host = next(filter(lambda h: h.hostname == hostname, host_pool.hosts), None)
         if not host:
             self.add_error("No Such Host ({}) exists".format(self.destination.value))
         elif host.status != HostStatus.alive:
             self.add_error("Destination Host is dead")
+        else:
+            self.destination.value = host.key
 
     def validation(self):
         vm = vm_pool.get(self.uuid.value)

common/classes.py

@@ -1,28 +1,6 @@
-from decouple import Config, RepositoryEnv, UndefinedValueError
 from etcd3_wrapper import EtcdEntry
 
 
-class EnvironmentVariables:
-    def __init__(self, env_file):
-        try:
-            env_config = Config(RepositoryEnv(env_file))
-        except FileNotFoundError:
-            print("{} does not exists".format(env_file))
-            exit(1)
-        else:
-            self.config = env_config
-
-    def get(self, *args, **kwargs):
-        """Return value of var from env_vars"""
-        try:
-            value = self.config.get(*args, **kwargs)
-        except UndefinedValueError as e:
-            print(e)
-            exit(1)
-        else:
-            return value
-
-
 class SpecificEtcdEntryBase:
     def __init__(self, e: EtcdEntry):
         self.key = e.key

common/helpers.py

@@ -1,5 +1,9 @@
 import logging
 import socket
+import requests
+import json
+
+from ipaddress import ip_address
 
 from os.path import join as join_path
 
@@ -37,3 +41,14 @@ def get_ipv4_address():
             address = s.getsockname()[0]
 
     return address
+
+
+def get_ipv6_address():
+    try:
+        r = requests.get("https://api6.ipify.org?format=json")
+        content = json.loads(r.content.decode("utf-8"))
+        ip = ip_address(content["ip"]).exploded
+    except Exception as e:
+        logging.exception(e)
+    else:
+        return ip

common/storage_handlers.py

@@ -0,0 +1,158 @@
+import shutil
+import subprocess as sp
+import os
+import stat
+
+from abc import ABC
+from host import logger
+from os.path import join as join_path
+
+
+class ImageStorageHandler(ABC):
+    def __init__(self, image_base, vm_base):
+        self.image_base = image_base
+        self.vm_base = vm_base
+
+    def import_image(self, image_src, image_dest, protect=False):
+        """Put an image at the destination
+        :param src: An Image file
+        :param dest: A path where :param src: is to be put.
+        :param protect: If protect is true then the dest is protect (readonly etc)
+        The obj must exist on filesystem.
+        """
+
+        raise NotImplementedError()
+
+    def make_vm_image(self, image_path, path):
+        """Copy image from src to dest
+
+        :param src: A path
+        :param dest: A path
+
+        src and destination must be on same storage system i.e both on file system or both on CEPH etc.
+        """
+        raise NotImplementedError()
+
+    def resize_vm_image(self, path, size):
+        """Resize image located at :param path:
+        :param path: The file which is to be resized
+        :param size: Size must be in Megabytes
+        """
+        raise NotImplementedError()
+
+    def delete_vm_image(self, path):
+        raise NotImplementedError()
+
+    def execute_command(self, command, report=True):
+        command = list(map(str, command))
+        try:
+            output = sp.check_output(command, stderr=sp.PIPE)
+        except Exception as e:
+            if report:
+                print(e)
+                logger.exception(e)
+            return False
+        return True
+
+    def vm_path_string(self, path):
+        raise NotImplementedError()
+
+    def qemu_path_string(self, path):
+        raise NotImplementedError()
+
+    def is_vm_image_exists(self, path):
+        raise NotImplementedError()
+
+
+class FileSystemBasedImageStorageHandler(ImageStorageHandler):
+    def import_image(self, src, dest, protect=False):
+        dest = join_path(self.image_base, dest)
+        try:
+            shutil.copy(src, dest)
+            if protect:
+                os.chmod(dest, stat.S_IRUSR | stat.S_IRGRP | stat.S_IROTH)
+        except Exception as e:
+            logger.exception(e)
+            return False
+        return True
+
+    def make_vm_image(self, src, dest):
+        src = join_path(self.image_base, src)
+        dest = join_path(self.vm_base, dest)
+        try:
+            shutil.copy(src, dest)
+        except Exception as e:
+            logger.exception(e)
+            return False
+        return True
+
+    def resize_vm_image(self, path, size):
+        path = join_path(self.vm_base, path)
+        command = ["qemu-img", "resize", "-f", "raw", path, "{}M".format(size)]
+        if self.execute_command(command):
+            return True
+        else:
+            self.delete_vm_image(path)
+            return False
+
+    def delete_vm_image(self, path):
+        path = join_path(self.vm_base, path)
+        try:
+            os.remove(path)
+        except Exception as e:
+            logger.exception(e)
+            return False
+        return True
+
+    def vm_path_string(self, path):
+        return join_path(self.vm_base, path)
+
+    def qemu_path_string(self, path):
+        return self.vm_path_string(path)
+
+    def is_vm_image_exists(self, path):
+        path = join_path(self.vm_base, path)
+        command = ["ls", path]
+        return self.execute_command(command, report=False)
+
+
+class CEPHBasedImageStorageHandler(ImageStorageHandler):
+    def import_image(self, src, dest, protect=False):
+        dest = join_path(self.image_base, dest)
+        command = ["rbd", "import", src, dest]
+        if protect:
+            snap_create_command = ["rbd", "snap", "create", "{}@protected".format(dest)]
+            snap_protect_command = ["rbd", "snap", "protect", "{}@protected".format(dest)]
+
+            return self.execute_command(command) and self.execute_command(snap_create_command) and\
+                self.execute_command(snap_protect_command)
+
+        return self.execute_command(command)
+
+    def make_vm_image(self, src, dest):
+        src = join_path(self.image_base, src)
+        dest = join_path(self.vm_base, dest)
+
+        command = ["rbd", "clone", "{}@protected".format(src), dest]
+        return self.execute_command(command)
+
+    def resize_vm_image(self, path, size):
+        path = join_path(self.vm_base, path)
+        command = ["rbd", "resize", path, "--size", size]
+        return self.execute_command(command)
+
+    def delete_vm_image(self, path):
+        path = join_path(self.vm_base, path)
+        command = ["rbd", "rm", path]
+        return self.execute_command(command)
+
+    def vm_path_string(self, path):
+        return join_path(self.vm_base, path)
+
+    def qemu_path_string(self, path):
+        return "rbd:{}".format(self.vm_path_string(path))
+
+    def is_vm_image_exists(self, path):
+        path = join_path(self.vm_base, path)
+        command = ["rbd", "info", path]
+        return self.execute_command(command, report=False)

common/vm.py

@@ -60,10 +60,6 @@ class VMEntry(SpecificEtcdEntryBase):
         self.log = self.log[:5]
         self.log.append("{} - {}".format(datetime.now().isoformat(), msg))
 
-    @property
-    def path(self):
-        return "rbd:uservms/{}".format(self.uuid)
-
 
 class VmPool:
     def __init__(self, etcd_client, vm_prefix):

config.py

@@ -1,14 +1,16 @@
 from etcd3_wrapper import Etcd3Wrapper
 
-from common.classes import EnvironmentVariables
 from common.host import HostPool
 from common.request import RequestPool
 from common.vm import VmPool
+from common.storage_handlers import FileSystemBasedImageStorageHandler, CEPHBasedImageStorageHandler
+from decouple import Config, RepositoryEnv
 
-env_vars = EnvironmentVariables('/etc/ucloud/ucloud.conf')
+
+env_vars = Config(RepositoryEnv('/etc/ucloud/ucloud.conf'))
 
 etcd_wrapper_args = ()
-etcd_wrapper_kwargs = {"host": env_vars.get("ETCD_URL")}
+etcd_wrapper_kwargs = {'host': env_vars.get('ETCD_URL')}
 
 etcd_client = Etcd3Wrapper(*etcd_wrapper_args, **etcd_wrapper_kwargs)
 
@@ -17,3 +19,12 @@ vm_pool = VmPool(etcd_client, env_vars.get('VM_PREFIX'))
 request_pool = RequestPool(etcd_client, env_vars.get('REQUEST_PREFIX'))
 
 running_vms = []
+
+__storage_backend = env_vars.get("STORAGE_BACKEND")
+if __storage_backend == "filesystem":
+    image_storage_handler = FileSystemBasedImageStorageHandler(vm_base=env_vars.get("VM_DIR"),
+                                                               image_base=env_vars.get("IMAGE_DIR"))
+elif __storage_backend == "ceph":
+    image_storage_handler = CEPHBasedImageStorageHandler(vm_base="ssd", image_base="ssd")
+else:
+    raise Exception("Unknown Image Storage Handler")

docs/source/diagram-code/ucloud

@@ -0,0 +1,44 @@
+graph LR
+    style ucloud fill:#FFD2FC
+    style cron fill:#FFF696
+    style infrastructure fill:#BDF0FF
+    subgraph ucloud[ucloud]
+        ucloud-cli[CLI]-->ucloud-api[API]
+        ucloud-api-->ucloud-scheduler[Scheduler]
+        ucloud-api-->ucloud-imagescanner[Image Scanner]
+        ucloud-api-->ucloud-host[Host]
+        ucloud-scheduler-->ucloud-host
+
+        ucloud-host-->need-networking{VM need Networking}
+        need-networking-->|Yes| networking-scripts
+        need-networking-->|No| VM[Virtual Machine]
+        need-networking-->|SLAAC?| radvd
+        networking-scripts-->VM
+        networking-scripts--Create Networks Devices-->networking-scripts
+        subgraph cron[Cron Jobs]
+            ucloud-imagescanner
+            ucloud-filescanner[File Scanner]
+            ucloud-filescanner--Track User files-->ucloud-filescanner
+        end
+ subgraph infrastructure[Infrastructure]
+    radvd
+    etcd
+    networking-scripts[Networking Scripts]
+    ucloud-imagescanner-->image-store
+    image-store{Image Store}
+    image-store-->|CEPH| ceph
+    image-store-->|FILE| file-system
+    ceph[CEPH]
+    file-system[File System]
+    end
+subgraph virtual-machine[Virtual Machine]
+  VM
+  VM-->ucloud-init
+
+end
+
+subgraph metadata-group[Metadata Server]
+metadata-->ucloud-init
+ucloud-init<-->metadata
+end
+end

docs/source/index.rst

@@ -1,7 +1,7 @@
 .. ucloud documentation master file, created by
-sphinx-quickstart on Mon Nov 11 19:08:16 2019.
-You can adapt this file completely to your liking, but it should at least
-contain the root `toctree` directive.
+   sphinx-quickstart on Mon Nov 11 19:08:16 2019.
+   You can adapt this file completely to your liking, but it should at least
+   contain the root `toctree` directive.
 
 Welcome to ucloud's documentation!
 ==================================
@@ -15,7 +15,9 @@ Welcome to ucloud's documentation!
    usage/usage-for-admins
    usage/usage-for-users
    usage/how-to-create-an-os-image-for-ucloud
+   theory/summary
    misc/todo
+   troubleshooting/installation-troubleshooting
 
 Indices and tables
 ==================

docs/source/introduction/installation.rst

@@ -135,7 +135,7 @@ You just need to update **AUTH_SEED** in the below code to match your auth's see
 
     ETCD_URL=localhost
 
-    WITHOUT_CEPH=True
+    STORAGE_BACKEND=filesystem
 
     BASE_DIR=/var/www
     IMAGE_DIR=/var/image
@@ -195,3 +195,35 @@ profile e.g *~/.profile*
     alias uotp='cd /root/uotp/ && pipenv run python app.py'
 
 and run :code:`source ~/.profile`
+
+
+Arch
+-----
+
+.. code-block:: sh
+
+    # Update/Upgrade
+    pacman -Syuu
+    pacman -S python3 qemu chrony python-pip
+
+    pip3 install pipenv
+
+    cat > /etc/chrony.conf << EOF
+    server 0.arch.pool.ntp.org
+    server 1.arch.pool.ntp.org
+    server 2.arch.pool.ntp.org
+    EOF
+
+    systemctl start chronyd
+    systemctl enable chronyd
+
+    # Create non-root user and allow it sudo access
+    # without password
+    useradd -m ucloud
+    echo "ucloud ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
+
+    sudo -H -u ucloud bash -c 'cd /home/ucloud && git clone https://aur.archlinux.org/yay.git && cd yay && makepkg -si'
+    sudo -H -u ucloud bash -c 'yay -S etcd'
+
+    systemctl start etcd
+    systemctl enable etcd

docs/source/misc/todo.rst

@@ -1,6 +1,18 @@
 TODO
 ====
 
+* **Check Authentication:** Nico reported that some endpoints
+  even work without providing token. (ListUserVM)
+
+* Put overrides for **IMAGE_BASE**, **VM_BASE** in **ImageStorageHandler**.
+
+* Put "Always use only one StorageHandler"
+
+* Create Network Manager
+    * That would handle tasks like up/down an interface
+    * Create VXLANs, Bridges, TAPs.
+    * Remove them when they are no longer used.
+
 * Check for :code:`etcd3.exceptions.ConnectionFailedError` when calling some etcd operation to
   avoid crashing whole application.
 * Throw KeyError instead of returning None when some key is not found in etcd.

docs/source/theory/summary.rst

@@ -0,0 +1,98 @@
+Summary
+=======
+
+.. image:: /images/ucloud.svg
+
+.. code-block::
+
+                              <cli>
+                                |
+                                |
+                                |
+    +-------------------------<api>
+    |                           |
+    |           |```````````````|```````````````|
+    |           |               |               |
+    |     <file_scanner>    <scheduler>   <image_scanner>
+    |                           |
+    |                           |
+    +-------------------------<host>
+                                |
+                                |
+                                |
+                         Virtual Machine------<init>------<metadata>
+
+
+
+**ucloud-cli** interact with **ucloud-api** to do the following operations:
+
+- Create/Delete/Start/Stop/Migrate/Probe (Status of) Virtual Machines
+- Create/Delete Networks
+- Add/Get/Delete SSH Keys
+- Create OS Image out of a file (tracked by file_scanner)
+- List User's files/networks/vms
+- Add Host
+
+ucloud can currently stores OS-Images on
+
+* File System
+* `CEPH <https://ceph.io/>`_
+
+
+**ucloud-api** in turns creates appropriate Requests which are taken
+by suitable components of ucloud. For Example, if user uses ucloud-cli
+to create a VM, **ucloud-api** would create a **ScheduleVMRequest** containing
+things like pointer to VM's entry which have specs, networking
+configuration of VMs.
+
+**ucloud-scheduler** accepts requests for VM's scheduling and
+migration. It finds a host from a list of available host on which
+the incoming VM can run and schedules it on that host.
+
+**ucloud-host** runs on host servers i.e servers that
+actually runs virtual machines, accepts requests
+intended only for them. It creates/delete/start/stop/migrate
+virtual machines. It also arrange network resources needed for the
+incoming VM.
+
+**ucloud-filescanner** keep tracks of user's files which would be needed
+later for creating OS Images.
+
+**ucloud-imagescanner** converts images files from qcow2 format to raw
+format which would then be imported into image store.
+
+* In case of **File System**, the converted image would be copied to
+  :file:`/var/image/` or the path referred by :envvar:`IMAGE_PATH` environement variable
+  mentioned in :file:`/etc/ucloud/ucloud.conf`.
+
+* In case of **CEPH**, the converted image would be imported into
+  specific pool (it depends on the image store in which the image
+  belongs) of CEPH Block Storage.
+
+**ucloud-metadata** provides metadata which is used to contextualize
+VMs. When, the VM is created, it is just clone (duplicate) of OS
+image from which it is created. So, to differentiate between my
+VM and your VM, the VM need to be contextualized. This works
+like the following
+
+.. note::
+    Actually, ucloud-init makes the GET request. You can also try it
+    yourself using curl but ucloud-init does that for yourself.
+
+* VM make a GET requests http://metadata which resolves to actual
+  address of metadata server. The metadata server looks at the IPv6
+  Address of the requester and extracts the MAC Address which is possible
+  because the IPv6 address is
+  `IPv6 EUI-64 <https://community.cisco.com/t5/networking-documents/understanding-ipv6-eui-64-bit-address/ta-p/3116953>`_.
+  Metadata use this MAC address to find the actual VM to which it belongs
+  and its owner, ssh-keys and much more. Then, metadata return these
+  details back to the calling VM in JSON format. These details are
+  then used be the **ucloud-init** which is explained next.
+
+**ucloud-init** gets the metadata from **ucloud-metadata** to contextualize
+the VM. Specifically, it gets owner's ssh keys (or any other keys the
+owner of VM added to authorized keys for this VM) and put them to ssh
+server's (installed on VM) authorized keys so that owner can access
+the VM using ssh. It also install softwares that are needed for correct
+behavior of VM e.g rdnssd (needed for `SLAAC <https://en.wikipedia.org/wiki/IPv6#Stateless_address_autoconfiguration_(SLAAC)>`_).
+

docs/source/troubleshooting/installation-troubleshooting.rst

@@ -0,0 +1,24 @@
+Installation Troubleshooting
+============================
+
+etcd doesn't start
+------------------
+
+.. code-block:: sh
+
+    [root@archlinux ~]# systemctl start etcd
+    Job for etcd.service failed because the control process exited with error code.
+    See "systemctl status etcd.service" and "journalctl -xe" for details
+
+possible solution
+~~~~~~~~~~~~~~~~~
+Try :code:`cat /etc/hosts` if its output contain the following
+
+.. code-block:: sh
+
+    127.0.0.1    localhost.localdomain localhost
+    ::1        localhost localhost.localdomain
+
+
+then unfortunately, we can't help you. But, if it doesn't contain the
+above you can put the above in :file:`/etc/hosts` to fix the issue.

filescanner/__init__.py

@@ -0,0 +1,3 @@
+import logging
+
+logger = logging.getLogger(__name__)

filescanner/main.py

@@ -6,7 +6,7 @@ import time
 from uuid import uuid4
 
 from etcd3_wrapper import Etcd3Wrapper
-
+from filescanner import logger
 from config import env_vars
 
 
@@ -17,9 +17,10 @@ def getxattr(file, attr):
         value = sp.check_output(['getfattr', file,
                                  '--name', attr,
                                  '--only-values',
-                                 '--absolute-names'])
+                                 '--absolute-names'], stderr=sp.DEVNULL)
         value = value.decode("utf-8")
-    except sp.CalledProcessError:
+    except sp.CalledProcessError as e:
+        logger.exception(e)
         value = None
 
     return value
@@ -63,7 +64,7 @@ try:
     sp.check_output(['which', 'getfattr'])
     sp.check_output(['which', 'setfattr'])
 except Exception as e:
-    print(e)
+    logger.exception(e)
     print('Make sure you have getfattr and setfattr available')
     exit(1)
 

host/helper.py

@@ -0,0 +1,13 @@
+import socket
+from contextlib import closing
+
+
+def find_free_port():
+    with closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as s:
+        try:
+            s.bind(('', 0))
+            s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        except Exception:
+            return None
+        else:
+            return s.getsockname()[1]

host/main.py

@@ -1,6 +1,5 @@
 import argparse
 import multiprocessing as mp
-import os
 import time
 
 from etcd3_wrapper import Etcd3Wrapper
@@ -10,13 +9,17 @@ from config import (vm_pool, request_pool,
                     etcd_client, running_vms,
                     etcd_wrapper_args, etcd_wrapper_kwargs,
                     HostPool, env_vars)
+
+from .helper import find_free_port
 from . import virtualmachine
 from host import logger
 
-def update_heartbeat(host):
+
+def update_heartbeat(hostname):
+    """Update Last HeartBeat Time for :param hostname: in etcd"""
     client = Etcd3Wrapper(*etcd_wrapper_args, **etcd_wrapper_kwargs)
     host_pool = HostPool(client, env_vars.get('HOST_PREFIX'))
-    this_host = next(filter(lambda h: h.hostname == host, host_pool.hosts), None)
+    this_host = next(filter(lambda h: h.hostname == hostname, host_pool.hosts), None)
 
     while True:
         this_host.update_heartbeat()
@@ -35,17 +38,22 @@ def maintenance(host):
     # whether this host vm is successfully migrated. If yes
     # then we shutdown "vm1" on this host.
 
+    to_be_removed = []
     for running_vm in running_vms:
         with vm_pool.get_put(running_vm.key) as vm_entry:
             if vm_entry.hostname != host.key and not vm_entry.in_migration:
                 running_vm.handle.shutdown()
-                vm_entry.add_log("VM on source host shutdown.")
+                logger.info("VM migration not completed successfully.")
+                to_be_removed.append(running_vm)
+
+    for r in to_be_removed:
+        running_vms.remove(r)
+
     # To check vm running according to etcd entries
     alleged_running_vms = vm_pool.by_status("RUNNING", vm_pool.by_host(host.key))
 
     for vm_entry in alleged_running_vms:
         _vm = virtualmachine.get_vm(running_vms, vm_entry.key)
-
         # Whether, the allegedly running vm is in our
         # running_vms list or not if it is said to be
         # running on this host but it is not then we
@@ -64,10 +72,6 @@ def maintenance(host):
 
 
 def main(hostname):
-    assert env_vars.get('WITHOUT_CEPH') and os.path.isdir(env_vars.get('VM_DIR')), (
-        "You have set env_vars.get('WITHOUT_CEPH') to True. So, the vm directory mentioned"
-        " in .env file must exists. But, it don't.")
-
     heartbeat_updating_process = mp.Process(target=update_heartbeat, args=(hostname,))
 
     host_pool = HostPool(etcd_client, env_vars.get('HOST_PREFIX'))
@@ -99,7 +103,6 @@ def main(hostname):
             request_event = RequestEntry(request_event)
 
             if request_event.type == "TIMEOUT":
-                logger.info("Timeout Event")
                 maintenance(host)
                 continue
 
@@ -121,7 +124,7 @@ def main(hostname):
                         virtualmachine.delete(vm_entry)
 
                     elif request_event.type == RequestType.InitVMMigration:
-                        virtualmachine.init_migration(vm_entry, host.key)
+                        virtualmachine.start(vm_entry, host.key, find_free_port())
 
                     elif request_event.type == RequestType.TransferVM:
                         virtualmachine.transfer(request_event)

host/qmp/__init__.py

@@ -304,6 +304,7 @@ class QEMUMachine(object):
                 LOG.debug('Command: %r', ' '.join(self._qemu_full_args))
             if self._iolog:
                 LOG.debug('Output: %r', self._iolog)
+                raise Exception(self._iolog)
             raise
 
     def _launch(self):

host/virtualmachine.py

@@ -4,27 +4,28 @@
 # For QEMU Monitor Protocol Commands Information, See
 # https://qemu.weilnetz.de/doc/qemu-doc.html#pcsys_005fmonitor
 
-import errno
 import os
 import random
 import subprocess as sp
 import tempfile
 import time
+
 from functools import wraps
-from os.path import join
+from os.path import join as join_path
 from string import Template
 from typing import Union
 
 import bitmath
 import sshtunnel
 
-from common.helpers import get_ipv4_address
+from common.helpers import get_ipv6_address
 from common.request import RequestEntry, RequestType
 from common.vm import VMEntry, VMStatus
-from config import etcd_client, request_pool, running_vms, vm_pool, env_vars
+from config import etcd_client, request_pool, running_vms, vm_pool, env_vars, image_storage_handler
 from . import qmp
 from host import logger
 
+
 class VM:
     def __init__(self, key, handle, vnc_socket_file):
         self.key = key  # type: str
@@ -106,24 +107,16 @@ def update_radvd_conf(etcd_client):
     sp.check_output(['systemctl', 'restart', 'radvd'])
 
 
-def get_start_command_args(
-        vm_entry, vnc_sock_filename: str, migration=False, migration_port=4444,
-):
+def get_start_command_args(vm_entry, vnc_sock_filename: str, migration=False, migration_port=None):
     threads_per_core = 1
-    vm_memory = int(bitmath.parse_string(vm_entry.specs["ram"]).to_MB())
+    vm_memory = int(bitmath.parse_string_unsafe(vm_entry.specs["ram"]).to_MB())
     vm_cpus = int(vm_entry.specs["cpu"])
     vm_uuid = vm_entry.uuid
     vm_networks = vm_entry.network
 
-    if env_vars.get('WITHOUT_CEPH'):
-        command = "-drive file={},format=raw,if=virtio,cache=none".format(
-            os.path.join(env_vars.get('VM_DIR'), vm_uuid)
-        )
-    else:
-        command = "-drive file=rbd:uservms/{},format=raw,if=virtio,cache=none".format(
-            vm_uuid
-        )
-
+    command = "-drive file={},format=raw,if=virtio,cache=none".format(
+        image_storage_handler.qemu_path_string(vm_uuid)
+    )
     command += " -device virtio-rng-pci -vnc unix:{}".format(vnc_sock_filename)
     command += " -m {} -smp cores={},threads={}".format(
         vm_memory, vm_cpus, threads_per_core
@@ -131,7 +124,7 @@ def get_start_command_args(
     command += " -name {}".format(vm_uuid)
 
     if migration:
-        command += " -incoming tcp:0:{}".format(migration_port)
+        command += " -incoming tcp:[::]:{}".format(migration_port)
 
     tap = None
     for network_and_mac in vm_networks:
@@ -154,7 +147,7 @@ def get_start_command_args(
     return command.split(" ")
 
 
-def create_vm_object(vm_entry, migration=False, migration_port=4444):
+def create_vm_object(vm_entry, migration=False, migration_port=None):
     # NOTE: If migration suddenly stop working, having different
     #       VNC unix filename on source and destination host can
     #       be a possible cause of it.
@@ -198,61 +191,19 @@ def need_running_vm(func):
 
 
 def create(vm_entry: VMEntry):
-    vm_hdd = int(bitmath.parse_string(vm_entry.specs["os-ssd"]).to_MB())
-
-    if env_vars.get('WITHOUT_CEPH'):
-        _command_to_create = [
-            "cp",
-            os.path.join(env_vars.get('IMAGE_DIR'), vm_entry.image_uuid),
-            os.path.join(env_vars.get('VM_DIR'), vm_entry.uuid),
-        ]
-
-        _command_to_extend = [
-            "qemu-img",
-            "resize",
-            "-f", "raw",
-            os.path.join(env_vars.get('VM_DIR'), vm_entry.uuid),
-            "{}M".format(vm_hdd),
-        ]
+    if image_storage_handler.is_vm_image_exists(vm_entry.uuid):
+        # File Already exists. No Problem Continue
+        logger.debug("Image for vm %s exists", vm_entry.uuid)
     else:
-        _command_to_create = [
-            "rbd",
-            "clone",
-            "images/{}@protected".format(vm_entry.image_uuid),
-            "uservms/{}".format(vm_entry.uuid),
-        ]
-
-        _command_to_extend = [
-            "rbd",
-            "resize",
-            "uservms/{}".format(vm_entry.uuid),
-            "--size",
-            vm_hdd,
-        ]
-
-    try:
-        sp.check_output(_command_to_create)
-    except sp.CalledProcessError as e:
-        if e.returncode == errno.EEXIST:
-            logger.debug("Image for vm %s exists", vm_entry.uuid)
-            # File Already exists. No Problem Continue
-            return
-
-        # This exception catches all other exceptions
-        # i.e FileNotFound (BaseImage), pool Does Not Exists etc.
-        logger.exception(e)
-
-        vm_entry.status = "ERROR"
-    else:
-        try:
-            sp.check_output(_command_to_extend)
-        except Exception as e:
-            logger.exception(e)
-        else:
-            logger.info("New VM Created")
+        vm_hdd = int(bitmath.parse_string_unsafe(vm_entry.specs["os-ssd"]).to_MB())
+        if image_storage_handler.make_vm_image(src=vm_entry.image_uuid, dest=vm_entry.uuid):
+            if not image_storage_handler.resize_vm_image(path=vm_entry.uuid, size=vm_hdd):
+                vm_entry.status = "ERROR"
+            else:
+                logger.info("New VM Created")
 
 
-def start(vm_entry: VMEntry):
+def start(vm_entry: VMEntry, destination_host_key=None, migration_port=None):
     _vm = get_vm(running_vms, vm_entry.key)
 
     # VM already running. No need to proceed further.
@@ -260,8 +211,12 @@ def start(vm_entry: VMEntry):
         logger.info("VM %s already running", vm_entry.uuid)
         return
     else:
-        create(vm_entry)
-        launch_vm(vm_entry)
+        if destination_host_key:
+            launch_vm(vm_entry, migration=True, migration_port=migration_port,
+                      destination_host_key=destination_host_key)
+        else:
+            create(vm_entry)
+            launch_vm(vm_entry)
 
 
 @need_running_vm
@@ -278,18 +233,9 @@ def stop(vm_entry):
 def delete(vm_entry):
     logger.info("Deleting VM | %s", vm_entry)
     stop(vm_entry)
-    path_without_protocol = vm_entry.path[vm_entry.path.find(":") + 1:]
 
-    if env_vars.get('WITHOUT_CEPH'):
-        vm_deletion_command = ["rm", os.path.join(env_vars.get('VM_DIR'), vm_entry.uuid)]
-    else:
-        vm_deletion_command = ["rbd", "rm", path_without_protocol]
-
-    try:
-        sp.check_output(vm_deletion_command)
-    except Exception as e:
-        logger.exception(e)
-    else:
+    r_status = image_storage_handler.delete_vm_image(vm_entry.uuid)
+    if r_status:
         etcd_client.client.delete(vm_entry.key)
 
 
@@ -301,15 +247,16 @@ def transfer(request_event):
     _host, _port = request_event.parameters["host"], request_event.parameters["port"]
     _uuid = request_event.uuid
     _destination = request_event.destination_host_key
-    vm = get_vm(running_vms, join(env_vars.get('VM_PREFIX'), _uuid))
+    vm = get_vm(running_vms, join_path(env_vars.get('VM_PREFIX'), _uuid))
 
     if vm:
         tunnel = sshtunnel.SSHTunnelForwarder(
-            (_host, 22),
+            _host,
             ssh_username=env_vars.get("ssh_username"),
             ssh_pkey=env_vars.get("ssh_pkey"),
-            ssh_private_key_password=env_vars.get("ssh_private_key_password"),
             remote_bind_address=("127.0.0.1", _port),
+            ssh_proxy_enabled=True,
+            ssh_proxy=(_host, 22)
         )
         try:
             tunnel.start()
@@ -317,7 +264,7 @@ def transfer(request_event):
             logger.exception("Couldn't establish connection to (%s, 22)", _host)
         else:
             vm.handle.command(
-                "migrate", uri="tcp:{}:{}".format(_host, tunnel.local_bind_port)
+                "migrate", uri="tcp:0.0.0.0:{}".format(tunnel.local_bind_port)
             )
 
             status = vm.handle.command("query-migrate")["status"]
@@ -340,38 +287,22 @@ def transfer(request_event):
             tunnel.close()
 
 
-def init_migration(vm_entry, destination_host_key):
-    # This function would run on destination host i.e host on which the vm
-    # would be transferred after migration.
-    # This host would be responsible for starting VM that would receive
-    # state of VM running on source host.
-
-    _vm = get_vm(running_vms, vm_entry.key)
-
-    if _vm:
-        # VM already running. No need to proceed further.
-        logger.info("%s Already running", _vm.key)
-        return
-
-    launch_vm(vm_entry, migration=True, migration_port=4444,
-              destination_host_key=destination_host_key)
-
-
 def launch_vm(vm_entry, migration=False, migration_port=None, destination_host_key=None):
     logger.info("Starting %s", vm_entry.key)
 
     vm = create_vm_object(vm_entry, migration=migration, migration_port=migration_port)
     try:
         vm.handle.launch()
-    except Exception as e:
-        logger.exception(e)
+    except Exception:
+        logger.exception("Error Occured while starting VM")
+        vm.handle.shutdown()
 
         if migration:
             # We don't care whether MachineError or any other error occurred
-            vm.handle.shutdown()
+            pass
         else:
             # Error during typical launch of a vm
-            vm_entry.add_log("Error Occurred while starting VM")
+            vm.handle.shutdown()
             vm_entry.declare_killed()
             vm_pool.put(vm_entry)
     else:
@@ -383,7 +314,7 @@ def launch_vm(vm_entry, migration=False, migration_port=None, destination_host_k
             r = RequestEntry.from_scratch(
                 type=RequestType.TransferVM,
                 hostname=vm_entry.hostname,
-                parameters={"host": get_ipv4_address(), "port": 4444},
+                parameters={"host": get_ipv6_address(), "port": migration_port},
                 uuid=vm_entry.uuid,
                 destination_host_key=destination_host_key,
                 request_prefix=env_vars.get("REQUEST_PREFIX")

imagescanner/main.py

@@ -1,9 +1,9 @@
 import json
 import os
 import subprocess
-import sys
 
-from config import etcd_client, env_vars
+from os.path import join as join_path
+from config import etcd_client, env_vars, image_storage_handler
 from imagescanner import logger
 
 
@@ -20,20 +20,6 @@ def qemu_img_type(path):
 
 
 def main():
-    # If you are using env_vars.get('WITHOUT_CEPH') FLAG in .env
-    # then please make sure that env_vars.get('IMAGE_DIR') directory
-    # exists otherwise this script would fail
-    if env_vars.get('WITHOUT_CEPH') and not os.path.isdir(env_vars.get('IMAGE_DIR')):
-        print("You have set env_vars.get('WITHOUT_CEPH') to True. So,"
-              "the {} must exists. But, it don't".format(env_vars.get('IMAGE_DIR')))
-        sys.exit(1)
-
-    try:
-        subprocess.check_output(['which', 'qemu-img'])
-    except Exception:
-        print("qemu-img missing")
-        sys.exit(1)
-
     # We want to get images entries that requests images to be created
     images = etcd_client.get_prefix(env_vars.get('IMAGE_PREFIX'), value_in_json=True)
     images_to_be_created = list(filter(lambda im: im.value['status'] == 'TO_BE_CREATED', images))
@@ -44,7 +30,7 @@ def main():
             image_owner = image.value['owner']
             image_filename = image.value['filename']
             image_store_name = image.value['store_name']
-            image_full_path = os.path.join(env_vars.get('BASE_DIR'), image_owner, image_filename)
+            image_full_path = join_path(env_vars.get('BASE_DIR'), image_owner, image_filename)
 
             image_stores = etcd_client.get_prefix(env_vars.get('IMAGE_STORE_PREFIX'), value_in_json=True)
             user_image_store = next(filter(
@@ -58,43 +44,25 @@ def main():
             logger.exception(e)
         else:
             # At least our basic data is available
-
             qemu_img_convert_command = ["qemu-img", "convert", "-f", "qcow2",
                                         "-O", "raw", image_full_path, "image.raw"]
 
-            if env_vars.get('WITHOUT_CEPH'):
-                image_import_command = ["mv", "image.raw", os.path.join(env_vars.get('IMAGE_DIR'), image_uuid)]
-                snapshot_creation_command = ["true"]
-                snapshot_protect_command = ["true"]
-            else:
-                image_import_command = ["rbd", "import", "image.raw",
-                                        "{}/{}".format(image_store_pool, image_uuid)]
-                snapshot_creation_command = ["rbd", "snap", "create",
-                                             "{}/{}@protected".format(image_store_pool, image_uuid)]
-                snapshot_protect_command = ["rbd", "snap", "protect",
-                                            "{}/{}@protected".format(image_store_pool, image_uuid)]
-
-            # First check whether the image is qcow2
-
             if qemu_img_type(image_full_path) == "qcow2":
                 try:
                     # Convert .qcow2 to .raw
                     subprocess.check_output(qemu_img_convert_command)
-
-                    # Import image either to ceph/filesystem
-                    subprocess.check_output(image_import_command)
-
-                    # Create and Protect Snapshot
-                    subprocess.check_output(snapshot_creation_command)
-                    subprocess.check_output(snapshot_protect_command)
-
                 except Exception as e:
                     logger.exception(e)
-
                 else:
-                    # Everything is successfully done
-                    image.value["status"] = "CREATED"
-                    etcd_client.put(image.key, json.dumps(image.value))
+                    # Import and Protect
+                    r_status = image_storage_handler.import_image(src="image.raw",
+                                                                  dest=image_uuid,
+                                                                  protect=True)
+                    if r_status:
+                        # Everything is successfully done
+                        image.value["status"] = "CREATED"
+                        etcd_client.put(image.key, json.dumps(image.value))
+
             else:
                 # The user provided image is either not found or of invalid format
                 image.value["status"] = "INVALID_IMAGE"

sanity_checks.py

@@ -0,0 +1,33 @@
+import sys
+import subprocess as sp
+
+from os.path import isdir
+from config import env_vars
+
+
+def check():
+    #########################
+    #  ucloud-image-scanner #
+    #########################
+    if env_vars.get('STORAGE_BACKEND') == 'filesystem' and not isdir(env_vars.get('IMAGE_DIR')):
+        print("You have set STORAGE_BACKEND to filesystem. So,"
+              "the {} must exists. But, it don't".format(env_vars.get('IMAGE_DIR')))
+        sys.exit(1)
+
+    try:
+        sp.check_output(['which', 'qemu-img'])
+    except Exception:
+        print("qemu-img missing")
+        sys.exit(1)
+
+    ###############
+    # ucloud-host #
+    ###############
+
+    if env_vars.get('STORAGE_BACKEND') == 'filesystem' and not isdir(env_vars.get('VM_DIR')):
+        print("You have set STORAGE_BACKEND to filesystem. So, the vm directory mentioned"
+              " in .env file must exists. But, it don't.")
+        sys.exit(1)
+
+if __name__ == "__main__":
+    check()

scheduler/helper.py

@@ -23,16 +23,16 @@ def remaining_resources(host_specs, vms_specs):
 
     for component in _vms_specs:
         if isinstance(_vms_specs[component], str):
-            _vms_specs[component] = int(bitmath.parse_string(_vms_specs[component]).to_MB())
+            _vms_specs[component] = int(bitmath.parse_string_unsafe(_vms_specs[component]).to_MB())
         elif isinstance(_vms_specs[component], list):
-            _vms_specs[component] = map(lambda x: int(bitmath.parse_string(x).to_MB()), _vms_specs[component])
+            _vms_specs[component] = map(lambda x: int(bitmath.parse_string_unsafe(x).to_MB()), _vms_specs[component])
             _vms_specs[component] = reduce(lambda x, y: x + y, _vms_specs[component], 0)
 
     for component in _remaining:
         if isinstance(_remaining[component], str):
-            _remaining[component] = int(bitmath.parse_string(_remaining[component]).to_MB())
+            _remaining[component] = int(bitmath.parse_string_unsafe(_remaining[component]).to_MB())
         elif isinstance(_remaining[component], list):
-            _remaining[component] = map(lambda x: int(bitmath.parse_string(x).to_MB()), _remaining[component])
+            _remaining[component] = map(lambda x: int(bitmath.parse_string_unsafe(x).to_MB()), _remaining[component])
             _remaining[component] = reduce(lambda x, y: x + y, _remaining[component], 0)
 
     _remaining.subtract(_vms_specs)

scheduler/main.py

@@ -23,8 +23,6 @@ def main():
     ]:
         for request_event in request_iterator:
             request_entry = RequestEntry(request_event)
-            logger.debug("%s, %s", request_entry.key, request_entry.value)
-
             # Never Run time critical mechanism inside timeout
             # mechanism because timeout mechanism only comes
             # when no other event is happening. It means under
@@ -33,10 +31,10 @@ def main():
 
                 # Detect hosts that are dead and set their status
                 # to "DEAD", and their VMs' status to "KILLED"
-                logger.debug("TIMEOUT event occured")
                 dead_hosts = dead_host_detection()
-                logger.debug("Dead hosts: %s", dead_hosts)
-                dead_host_mitigation(dead_hosts)
+                if dead_hosts:
+                    logger.debug("Dead hosts: %s", dead_hosts)
+                    dead_host_mitigation(dead_hosts)
 
                 # If there are VMs that weren't assigned a host
                 # because there wasn't a host available which
@@ -52,6 +50,8 @@ def main():
                     request_pool.put(r)
 
             elif request_entry.type == RequestType.ScheduleVM:
+                logger.debug("%s, %s", request_entry.key, request_entry.value)
+
                 vm_entry = vm_pool.get(request_entry.uuid)
                 if vm_entry is None:
                     logger.info("Trying to act on {} but it is deleted".format(request_entry.uuid))
@@ -67,7 +67,7 @@ def main():
                                           hosts=[host_pool.get(request_entry.destination)])
                     except NoSuitableHostFound:
                         logger.info("Requested destination host doesn't have enough capacity"
-                                     "to hold %s", vm_entry.uuid)
+                                     "to hold %s" % vm_entry.uuid)
                     else:
                         r = RequestEntry.from_scratch(type=RequestType.InitVMMigration,
                                                       uuid=request_entry.uuid,

ucloud.py

@@ -3,6 +3,7 @@ import multiprocessing as mp
 import logging
 
 from os.path import join as join_path
+from sanity_checks import check
 
 if __name__ == "__main__":
     arg_parser = argparse.ArgumentParser(prog='ucloud',
@@ -21,30 +22,36 @@ if __name__ == "__main__":
         format="%(name)s %(asctime)s: %(levelname)s - %(message)s",
         datefmt="%d-%b-%y %H:%M:%S",
     )
+    try:
+        check()
 
-    if args.component == 'api':
-        from api.main import main
+        if args.component == 'api':
+            from api.main import main
 
-        main()
-    elif args.component == 'host':
-        from host.main import main
+            main()
+        elif args.component == 'host':
+            from host.main import main
 
-        hostname = args.component_args
-        mp.set_start_method('spawn')
-        main(*hostname)
-    elif args.component == 'scheduler':
-        from scheduler.main import main
+            hostname = args.component_args
+            mp.set_start_method('spawn')
+            main(*hostname)
+        elif args.component == 'scheduler':
+            from scheduler.main import main
 
-        main()
-    elif args.component == 'filescanner':
-        from filescanner.main import main
+            main()
+        elif args.component == 'filescanner':
+            from filescanner.main import main
 
-        main()
-    elif args.component == 'imagescanner':
-        from imagescanner.main import main
+            main()
+        elif args.component == 'imagescanner':
+            from imagescanner.main import main
 
-        main()
-    elif args.component == 'metadata':
-        from metadata.main import main
+            main()
+        elif args.component == 'metadata':
+            from metadata.main import main
 
-        main()
+            main()
+
+    except Exception as e:
+        logging.exception(e)
+        print(e)