block-device: change top level config from dict to list

With the old configuration structure it was only possible
to use one image and one partition layout.  The new
block-device configuration uses a list at top level;
therefore it is possible to use multiple instances
of each element type.

Change-Id: I9db4327486b676887d6ce09609994116dbebfc89
Signed-off-by: Andreas Florath <andreas@florath.net>

diskimage_builder/block_device/blockdevice.py

@@ -34,13 +34,13 @@ class BlockDevice(object):
     # Default configuration:
     # one image, one partition, mounted under '/'
     DefaultConfig = """
-local_loop:
-  name: image0
+- local_loop:
+    name: image0
 """
 
 # This is an example of the next level config
 # mkfs:
-#  base: root_p1
+#  base: root
 #  type: ext4
 #  mount_point: /
 
@@ -85,7 +85,16 @@ local_loop:
         # add the appropriate nodes and edges.
         dg = Digraph()
 
-        for cfg_obj_name, cfg_obj_val in config.items():
+        for config_entry in config:
+            if len(config_entry) != 1:
+                logger.error("Invalid config entry: more than one key "
+                             "on top level [%s]" % config_entry)
+                raise BlockDeviceSetupException(
+                    "Top level config must contain exactly one key per entry")
+            logger.debug("Config entry [%s]" % config_entry)
+            cfg_obj_name = config_entry.keys()[0]
+            cfg_obj_val = config_entry[cfg_obj_name]
+
             # As the first step the configured objects are created
             # (if it exists)
             if cfg_obj_name not in BlockDevice.cfg_type_map:
@@ -132,8 +141,8 @@ local_loop:
         # result to stdout.
         # If there is no partition needed, pass back directly the
         # image.
-        if 'root_p1' in result:
-            print("%s" % result['root_p1']['device'])
+        if 'root' in result:
+            print("%s" % result['root']['device'])
         else:
             print("%s" % result['image0']['device'])
 

diskimage_builder/elements/vm/environment.d/10-partitioning

@@ -1,14 +1,14 @@
 export DIB_BLOCK_DEVICE_DEFAULT_CONFIG="
-local_loop:
-  name: image0
+- local_loop:
+    name: image0
 
-partitioning:
-  base: image0
-  label: mbr
-  partitions:
-    - name: root_p1
-      flags: [ boot, primary ]
-      size: 100%
+- partitioning:
+   base: image0
+   label: mbr
+   partitions:
+     - name: root
+       flags: [ boot, primary ]
+       size: 100%
 "
 
 DIB_BLOCK_DEVICE_CONFIG=${DIB_BLOCK_DEVICE_CONFIG:-${DIB_BLOCK_DEVICE_DEFAULT_CONFIG}}

doc/source/user_guide/building_an_image.rst

@@ -60,7 +60,7 @@ formats are:
 Disk Image Layout
 -----------------
 
-When generating a block image (e.g. qcow2 or raw), by default one
+When generating a vm block image (e.g. qcow2 or raw), by default one
 image with one partition holding all files is created.
 
 The configuration is done by means of the environment variable
@@ -72,16 +72,16 @@ The default is:
 ::
 
     DIB_BLOCK_DEVICE_CONFIG='
-      local_loop:
-        name: image0
+      - local_loop:
+          name: image0
 
-      partitioning:
-        base: image0
-        label: mbr
-        partitions:
-          - name: root_p1
-            flags: [ boot, primary ]
-            size: 100%'
+      - partitioning:
+          base: image0
+          label: mbr
+          partitions:
+            - name: root
+              flags: [ boot, primary ]
+              size: 100%'
 
 In general each module that depends on another module has a `base`
 element that points to the depending base.
@@ -103,7 +103,7 @@ all but the `image0` will be not useable (are deleted during the
 build process).
 
 Currently only one partitions is used for the image.  The name of this
-partition must be `root_p1`.  Other partitions are created but not
+partition must be `root`.  Other partitions are created but not
 used.
 
 Level 0
@@ -239,26 +239,26 @@ size
 Example:
 
 ::
-        partitioning:
-          base: image0
-          label: mbr
-          partitions:
-            - name: part-01
-              flags: [ boot ]
-              size: 1GiB
-            - name: part-02
-              size: 100%
+        - partitioning:
+            base: image0
+            label: mbr
+            partitions:
+              - name: part-01
+                flags: [ boot ]
+                size: 1GiB
+              - name: part-02
+                size: 100%
 
-        partitioning:
-          base: data_image
-          label: mbr
-          partitions:
-            - name: data0
-              size: 33%
-            - name: data1
-              size: 50%
-            - name: data2
-              size: 100%
+        - partitioning:
+            base: data_image
+            label: mbr
+            partitions:
+              - name: data0
+                size: 33%
+              - name: data1
+                size: 50%
+              - name: data2
+                size: 100%
 
 On the `image0` two partitions are created.  The size of the first is
 1GiB, the second uses the remaining free space.  On the `data_image`