diff --git a/diskimage_builder/block_device/blockdevice.py b/diskimage_builder/block_device/blockdevice.py
index 897c0d4bc..18b5e55e8 100644
--- a/diskimage_builder/block_device/blockdevice.py
+++ b/diskimage_builder/block_device/blockdevice.py
@@ -15,13 +15,12 @@
import codecs
from diskimage_builder.block_device.blockdevicesetupexception \
import BlockDeviceSetupException
-from diskimage_builder.block_device.level0 import LocalLoop
-from diskimage_builder.block_device.level1 import Partitioning
from diskimage_builder.graph.digraph import Digraph
import json
import logging
import os
import shutil
+from stevedore import extension
import sys
import yaml
@@ -85,13 +84,6 @@ class BlockDevice(object):
# type: ext4
# mount_point: /
- # A dictionary to map sensible names to internal implementation.
- cfg_type_map = {
- 'local_loop': LocalLoop,
- 'partitioning': Partitioning,
- 'mkfs': 'not yet implemented',
- }
-
def __init__(self, block_device_config, build_dir,
default_image_size, default_image_dir):
logger.debug("Creating BlockDevice object")
@@ -109,6 +101,9 @@ class BlockDevice(object):
"states/block-device")
self.state_json_file_name \
= os.path.join(self.state_dir, "state.json")
+ self.plugin_manager = extension.ExtensionManager(
+ namespace='diskimage_builder.block_device.plugin',
+ invoke_on_load=False)
def write_state(self, result):
logger.debug("Write state [%s]" % self.state_json_file_name)
@@ -138,11 +133,11 @@ class BlockDevice(object):
# As the first step the configured objects are created
# (if it exists)
- if cfg_obj_name not in BlockDevice.cfg_type_map:
+ if cfg_obj_name not in self.plugin_manager:
logger.error("Configured top level element [%s] "
"does not exists." % cfg_obj_name)
return 1
- cfg_obj = BlockDevice.cfg_type_map[cfg_obj_name](
+ cfg_obj = self.plugin_manager[cfg_obj_name].plugin(
cfg_obj_val, default_config)
# At this point it is only possible to add the nodes:
# adding the edges needs all nodes first.
diff --git a/diskimage_builder/block_device/level0/localloop.py b/diskimage_builder/block_device/level0/localloop.py
index 7fd21b3d3..dfa543d8d 100644
--- a/diskimage_builder/block_device/level0/localloop.py
+++ b/diskimage_builder/block_device/level0/localloop.py
@@ -14,6 +14,7 @@
from diskimage_builder.block_device.blockdevicesetupexception \
import BlockDeviceSetupException
+from diskimage_builder.block_device.plugin_base import NodePluginBase
from diskimage_builder.block_device.utils import parse_abs_size_spec
from diskimage_builder.graph.digraph import Digraph
import logging
@@ -24,15 +25,13 @@ import subprocess
logger = logging.getLogger(__name__)
-class LocalLoop(Digraph.Node):
+class LocalLoop(NodePluginBase):
"""Level0: Local loop image device handling.
This class handles local loop devices that can be used
for VM image installation.
"""
- type_string = "local_loop"
-
def __init__(self, config, default_config):
logger.debug("Creating LocalLoop object; config [%s] "
"default_config [%s]" % (config, default_config))
@@ -50,9 +49,6 @@ class LocalLoop(Digraph.Node):
Digraph.Node.__init__(self, self.name)
self.filename = os.path.join(self.image_dir, self.name + ".raw")
- def insert_nodes(self, dg):
- dg.add_node(self)
-
def insert_edges(self, dg):
"""Because this is created without base, there are no edges."""
pass
diff --git a/diskimage_builder/block_device/level1/partitioning.py b/diskimage_builder/block_device/level1/partitioning.py
index 28f2a688e..2d79ddb5c 100644
--- a/diskimage_builder/block_device/level1/partitioning.py
+++ b/diskimage_builder/block_device/level1/partitioning.py
@@ -16,6 +16,7 @@ import collections
from diskimage_builder.block_device.blockdevicesetupexception \
import BlockDeviceSetupException
from diskimage_builder.block_device.level1.mbr import MBR
+from diskimage_builder.block_device.plugin_base import PluginBase
from diskimage_builder.block_device.utils import parse_abs_size_spec
from diskimage_builder.block_device.utils import parse_rel_size_spec
from diskimage_builder.graph.digraph import Digraph
@@ -67,9 +68,7 @@ class Partition(Digraph.Node):
pass
-class Partitioning(object):
-
- type_string = "partitioning"
+class Partitioning(PluginBase):
flag_boot = 1
flag_primary = 2
diff --git a/diskimage_builder/block_device/plugin_base.py b/diskimage_builder/block_device/plugin_base.py
new file mode 100644
index 000000000..c92ff77c9
--- /dev/null
+++ b/diskimage_builder/block_device/plugin_base.py
@@ -0,0 +1,51 @@
+# Copyright 2017 Andreas Florath (andreas@florath.net)
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import abc
+from diskimage_builder.graph.digraph import Digraph
+import six
+
+
+@six.add_metaclass(abc.ABCMeta)
+class PluginBase(object):
+ """Abstract base class for block device plugins"""
+
+ def __init__(self, name):
+ """All plugins must have a name"""
+ self.name = name
+
+ @abc.abstractmethod
+ def create(self, state, rollback):
+ """Create the block device plugin
+
+ :param state: a dictionary to store results for this plugin.
+ These are used in two scenarios: other plugins
+ can use this to get information about the
+ result of the plugin and it can be used in
+ later runs of dib-block-device for cleaning up.
+ :type state: dict(str:?)
+
+ :param rollback: a list of python functions that will be
+ called in reversed order to cleanup if there
+ occurs an error later within the same
+ dib-block-device run.
+ :type rollback: list(function)
+ """
+
+
+class NodePluginBase(PluginBase, Digraph.Node):
+
+ def insert_nodes(self, dg):
+ """Adds self as a node to the given digraph"""
+ dg.add_node(self)
diff --git a/requirements.txt b/requirements.txt
index 2f2d10936..6077f0c3f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,3 +6,4 @@ pbr>=2.0.0 # Apache-2.0
PyYAML>=3.10.0 # MIT
flake8<2.6.0,>=2.5.4 # MIT
six>=1.9.0 # MIT
+stevedore>=1.20.0 # Apache-2.0
diff --git a/setup.cfg b/setup.cfg
index 5eac87455..6a42eb0c7 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -56,3 +56,7 @@ console_scripts =
disk-image-create = diskimage_builder.disk_image_create:main
ramdisk-image-create = diskimage_builder.disk_image_create:main
dib-run-parts = diskimage_builder.dib_run_parts:main
+
+diskimage_builder.block_device.plugin =
+ local_loop = diskimage_builder.block_device.level0.localloop:LocalLoop
+ partitioning = diskimage_builder.block_device.level1.partitioning:Partitioning