Merge ~raharper/cloud-init:network-config-doc into cloud-init:master

[Ryan Harper]

doc: document network configuration defaults, policy, formats and examples

Add documentation for cloud-init networking configuration formats, default
behavior, policy and other specific details about how network config is
consumed and utilized.

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review: Approve (continuous-integration)

[Scott Moser (smoser)]

Ryan, this looks really good.
you did a lot of sleuthing!

there are some comments inline, i read mostly around the 'cloud-init' parts, i very lightly skimmed the v1 and v2 doc sections.

[Scott Moser (smoser)]

Ryan, this looks really good.
you did a lot of sleuthing!

there are some comments inline, i read mostly around the 'cloud-init' parts, i very lightly skimmed the v1 and v2 doc sections.

[Ryan Harper (raharper)]

Thanks for the input; I'll update.

4990a43... by Ryan Harper on 2017-03-30

Incorporate MR feedback, remove trailing whitespace.

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review: Approve (continuous-integration)

e3df470... by Scott Moser on 2017-04-21

silence warning about yaml format by explicitly stating code block format

f9acbc2... by Scott Moser on 2017-04-21

input format is legacy. output format is fine (and required by current OSes)

c46692d... by Scott Moser on 2017-04-21

system config does not come under system_info

[Scott Moser (smoser)]

only a few small things inline.
and also i have done some commits on top of this at
 https://code.launchpad.net/~smoser/cloud-init/+git/cloud-init/+ref/network-config-docs

so just pull those into yours if you agree.

review: Needs Fixing

5a452c4... by Ryan Harper on 2017-04-26

Wrap lines < 80

bd2ae47... by Ryan Harper on 2017-04-26

Merge remote-tracking branch 'smoser-cloudinit/network-config-docs' into network-config-doc

e3e1ef6... by Ryan Harper on 2017-04-26

remove documentation on disabling during upgrade

b773c3c... by Ryan Harper on 2017-04-26

Drop system_info as config space key; rename to cloud config

41e0e8e... by Ryan Harper on 2017-04-26

Add vlan to list of ignored interfaces for fallback

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review: Approve (continuous-integration)

42e5031... by Ryan Harper on 2017-04-26

Remove interface selection algorithm details

e1d999a... by Ryan Harper on 2017-04-26

Reword network config background, fix ConfigDrive network sources

[Ryan Harper (raharper)]

OK, I've addressed the comments, and merged your network-config-doc branch. Please re-review.

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review: Approve (continuous-integration)

3e5f2fe... by Ryan Harper on 2017-05-03

Merge in additional feedback.

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diff --git a/doc/rtd/index.rst b/doc/rtd/index.rst
index 8f163b6..a691103 100644
--- a/doc/rtd/index.rst
+++ b/doc/rtd/index.rst
@@ -38,6 +38,7 @@ initialization of a cloud instance.
    topics/logging.rst
    topics/modules.rst
    topics/merging.rst
+   topics/network-config.rst
    topics/vendordata.rst
    topics/moreinfo.rst
    topics/hacking.rst
diff --git a/doc/rtd/topics/datasources/altcloud.rst b/doc/rtd/topics/datasources/altcloud.rst
index 202b0a4..eeb197f 100644
--- a/doc/rtd/topics/datasources/altcloud.rst
+++ b/doc/rtd/topics/datasources/altcloud.rst
@@ -1,3 +1,5 @@
+.. _datasource_alt_cloud:
+
 Alt Cloud
 =========
 
diff --git a/doc/rtd/topics/datasources/azure.rst b/doc/rtd/topics/datasources/azure.rst
index 18d7c50..4a3735b 100644
--- a/doc/rtd/topics/datasources/azure.rst
+++ b/doc/rtd/topics/datasources/azure.rst
@@ -1,3 +1,5 @@
+.. _datasource_azure:
+
 Azure
 =====
 
diff --git a/doc/rtd/topics/datasources/cloudsigma.rst b/doc/rtd/topics/datasources/cloudsigma.rst
index 54963f6..86b834c 100644
--- a/doc/rtd/topics/datasources/cloudsigma.rst
+++ b/doc/rtd/topics/datasources/cloudsigma.rst
@@ -1,3 +1,5 @@
+.. _datasource_cloudsigma:
+
 CloudSigma
 ==========
 
diff --git a/doc/rtd/topics/datasources/cloudstack.rst b/doc/rtd/topics/datasources/cloudstack.rst
index 04603d9..225093a 100644
--- a/doc/rtd/topics/datasources/cloudstack.rst
+++ b/doc/rtd/topics/datasources/cloudstack.rst
@@ -1,3 +1,5 @@
+.. _datasource_cloudstack:
+
 CloudStack
 ==========
 
diff --git a/doc/rtd/topics/datasources/configdrive.rst b/doc/rtd/topics/datasources/configdrive.rst
index 11dd52a..f1a488a 100644
--- a/doc/rtd/topics/datasources/configdrive.rst
+++ b/doc/rtd/topics/datasources/configdrive.rst
@@ -1,3 +1,5 @@
+.. _datasource_config_drive:
+
 Config Drive
 ============
 
diff --git a/doc/rtd/topics/datasources/digitalocean.rst b/doc/rtd/topics/datasources/digitalocean.rst
index c6f5bc7..938ede8 100644
--- a/doc/rtd/topics/datasources/digitalocean.rst
+++ b/doc/rtd/topics/datasources/digitalocean.rst
@@ -1,3 +1,5 @@
+.. _datasource_digital_ocean:
+
 Digital Ocean
 =============
 
diff --git a/doc/rtd/topics/datasources/ec2.rst b/doc/rtd/topics/datasources/ec2.rst
index 4810c98..3bc66e1 100644
--- a/doc/rtd/topics/datasources/ec2.rst
+++ b/doc/rtd/topics/datasources/ec2.rst
@@ -1,3 +1,5 @@
+.. _datasource_ec2:
+
 Amazon EC2
 ==========
 
diff --git a/doc/rtd/topics/datasources/fallback.rst b/doc/rtd/topics/datasources/fallback.rst
index 1eb01dd..2b133fc 100644
--- a/doc/rtd/topics/datasources/fallback.rst
+++ b/doc/rtd/topics/datasources/fallback.rst
@@ -1,3 +1,5 @@
+.. _datasource_fallback:
+
 Fallback/None
 =============
 
diff --git a/doc/rtd/topics/datasources/maas.rst b/doc/rtd/topics/datasources/maas.rst
index f495dd4..85c853e 100644
--- a/doc/rtd/topics/datasources/maas.rst
+++ b/doc/rtd/topics/datasources/maas.rst
@@ -1,3 +1,5 @@
+.. _datasource_maas:
+
 MAAS
 ====
 
diff --git a/doc/rtd/topics/datasources/nocloud.rst b/doc/rtd/topics/datasources/nocloud.rst
index b9ab5f1..0159e85 100644
--- a/doc/rtd/topics/datasources/nocloud.rst
+++ b/doc/rtd/topics/datasources/nocloud.rst
@@ -1,3 +1,5 @@
+.. _datasource_nocloud:
+
 NoCloud
 =======
 
@@ -70,6 +72,43 @@ Example metadata:
       gateway 192.168.1.254
     hostname: myhost
 
+
+Network configuration can also be provided to cloud-init in either
+:ref:`network_config_v1` or :ref:`network_config_v2` by providing that
+yaml formatted data in a file named ``network-config``.  If found,
+this file will override a ``network-interfaces`` file.
+
+See an example below.  Note specifically that this file does not
+have a top level ``network`` key as it it is already assumed to
+be network configuration based on the filename.
+
+.. code:: yaml
+
+  version: 1
+  config:
+     - type: physical
+       name: interface0
+       mac_address: "52:54:00:12:34:00"
+       subnets:
+          - type: static
+            address: 192.168.1.10
+            netmask: 255.255.255.0
+            gateway: 192.168.1.254
+
+
+.. code:: yaml
+
+  version: 2
+  ethernets:
+    interface0:
+       match:
+           mac_address: "52:54:00:12:34:00"
+       set-name: interface0
+       addresses:
+       - 192.168.1.10/255.255.255.0
+       gateway4: 192.168.1.254
+
+
 .. _iso9660: https://en.wikipedia.org/wiki/ISO_9660
 .. _vfat: https://en.wikipedia.org/wiki/File_Allocation_Table
 .. vi: textwidth=78
diff --git a/doc/rtd/topics/datasources/opennebula.rst b/doc/rtd/topics/datasources/opennebula.rst
index 1b90a9c..7c0367c 100644
--- a/doc/rtd/topics/datasources/opennebula.rst
+++ b/doc/rtd/topics/datasources/opennebula.rst
@@ -1,3 +1,5 @@
+.. _datasource_opennebula:
+
 OpenNebula
 ==========
 
diff --git a/doc/rtd/topics/datasources/openstack.rst b/doc/rtd/topics/datasources/openstack.rst
index 164b0e0..607b70f 100644
--- a/doc/rtd/topics/datasources/openstack.rst
+++ b/doc/rtd/topics/datasources/openstack.rst
@@ -1,3 +1,5 @@
+.. _datasource_openstack:
+
 OpenStack
 =========
 
diff --git a/doc/rtd/topics/datasources/ovf.rst b/doc/rtd/topics/datasources/ovf.rst
index a077033..c312617 100644
--- a/doc/rtd/topics/datasources/ovf.rst
+++ b/doc/rtd/topics/datasources/ovf.rst
@@ -1,3 +1,5 @@
+.. _datasource_ovf:
+
 OVF
 ===
 
diff --git a/doc/rtd/topics/datasources/smartos.rst b/doc/rtd/topics/datasources/smartos.rst
index a1e1542..cb9a128 100644
--- a/doc/rtd/topics/datasources/smartos.rst
+++ b/doc/rtd/topics/datasources/smartos.rst
@@ -1,3 +1,5 @@
+.. _datasource_smartos:
+
 SmartOS Datasource
 ==================
 
diff --git a/doc/rtd/topics/network-config-format-eni.rst b/doc/rtd/topics/network-config-format-eni.rst
new file mode 100644
index 0000000..f9ecaf7
--- /dev/null
+++ b/doc/rtd/topics/network-config-format-eni.rst
@@ -0,0 +1,19 @@
+.. _network_config_eni:
+
+Network Configuration ENI (Legacy)
+----------------------------------
+
+`Cloud-init`_ supports reading and writing network config in the ``ENI``
+format which is consumed by the ``ifupdown`` tool to parse and apply network
+configuration.
+
+As an input format this is **legacy** and `Cloud-init`_.  In cases where
+ENI format is available and another format is also available, it will
+prefer to use the other format.  This can happen in either :ref:`datasource_nocloud` or
+:ref:`datasource_openstack` datasources.
+
+Please reference existing `documentation`_ for the ``/etc/network/interfaces(5)`` format.
+
+.. _Cloud-init: https://launchpad.net/cloud-init
+.. _documentation: http://manpages.ubuntu.com/manpages/trusty/en/man5/interfaces.5.html
+.. vi: textwidth=78
diff --git a/doc/rtd/topics/network-config-format-v1.rst b/doc/rtd/topics/network-config-format-v1.rst
new file mode 100644
index 0000000..f5f5d5d
--- /dev/null
+++ b/doc/rtd/topics/network-config-format-v1.rst
@@ -0,0 +1,555 @@
+.. _network_config_v1:
+
+Networking Config Version 1
+===========================
+
+This network configuration format lets users customize their instance's
+networking interfaces by assigning subnet configuration, virtual device
+creation (bonds, bridges, vlans) routes and DNS configuration.
+
+Required elements of a Network Config Version 1 are ``config`` and
+``version``.
+
+Cloud-init will read this format from system config.
+For example the following could be present in
+``/etc/cloud/cloud.cfg.d/custom-networking.cfg``:
+
+.. code-block:: yaml
+
+  network:
+    version: 1
+    config:
+    - type: physical
+      name: eth0
+      subnets:
+        - type: dhcp
+
+The :ref:`datasource_nocloud` datasource can also provide cloud-init networking
+configuration in this Format.
+
+Configuration Types
+-------------------
+Within the network ``config`` portion, users include a list of configuration
+types.  The current list of support ``type`` values are as follows:
+
+- Physical (``physical``)
+- Bond (``bond``)
+- Bridge (``bridge``)
+- VLAN (``vlan``)
+- Nameserver (``nameserver``)
+- Route (``route``)
+
+Physical, Bond, Bridge and VLAN types may also include IP configuration under
+the key ``subnets``.
+
+- Subnet/IP (``subnets``)
+
+
+Physical
+~~~~~~~~
+The ``physical`` type configuration represents a "physical" network device,
+typically Ethernet-based.  At least one of of these entries is required for
+external network connectivity.  Type ``physical`` requires only one key:
+``name``.  A ``physical`` device may contain some or all of the following keys:
+
+**name**: *<desired device name>*
+
+A devices name must be less than 15 characters.  Names exceeding the maximum
+will be truncated. This is a limitation of the Linux kernel network-device
+structure.
+
+**mac_address**: *<MAC Address>*
+
+The MAC Address is a device unique identifier that most Ethernet-based network
+devices possess.  Specifying a MAC Address is optional.
+
+
+.. note::
+
+  Cloud-init will handle the persistent mapping between a
+  device's ``name`` and the ``mac_address``.
+
+**mtu**: *<MTU SizeBytes>*
+
+The MTU key represents a device's Maximum Transmission Unit, the largest size
+packet or frame, specified in octets (eight-bit bytes), that can be sent in a
+packet- or frame-based network.  Specifying ``mtu`` is optional.
+
+.. note::
+
+  The possible supported values of a device's MTU is not available at
+  configuration time.  It's possible to specify a value too large or to
+  small for a device and may be ignored by the device.
+
+
+**Physical Example**::
+
+  network:
+    version: 1
+    config:
+      # Simple network adapter
+      - type: physical
+        name: interface0
+        mac_address: 00:11:22:33:44:55
+      # Second nic with Jumbo frames
+      - type: physical
+        name: jumbo0
+        mac_address: aa:11:22:33:44:55
+        mtu: 9000
+      # 10G pair
+      - type: physical
+        name: gbe0
+        mac_address: cd:11:22:33:44:00
+      - type: physical
+        name: gbe1
+        mac_address: cd:11:22:33:44:02
+
+Bond
+~~~~
+A ``bond`` type will configure a Linux software Bond with one or more network
+devices.  A ``bond`` type requires the following keys:
+
+**name**: *<desired device name>*
+
+A devices name must be less than 15 characters.  Names exceeding the maximum
+will be truncated. This is a limitation of the Linux kernel network-device
+structure.
+
+**mac_address**: *<MAC Address>*
+
+When specifying MAC Address on a bond this value will be assigned to the bond
+device and may be different than the MAC address of any of the underlying
+bond interfaces.  Specifying a MAC Address is optional.  If ``mac_address`` is
+not present, then the bond will use one of the MAC Address values from one of
+the bond interfaces.
+
+
+**bond_interfaces**: *<List of network device names>*
+
+The ``bond_interfaces`` key accepts a list of network device ``name`` values
+from the configuration.  This list may be empty.
+
+**params**:  *<Dictionary of key: value bonding parameter pairs>*
+
+The ``params`` key in a bond holds a dictionary of bonding parameters.
+This dictionary may be empty. For more details on what the various bonding
+parameters mean please read the Linux Kernel Bonding.txt.
+
+Valid ``params`` keys are:
+
+  - ``active_slave``: Set bond attribute
+  - ``ad_actor_key``: Set bond attribute
+  - ``ad_actor_sys_prio``: Set bond attribute
+  - ``ad_actor_system``: Set bond attribute
+  - ``ad_aggregator``: Set bond attribute
+  - ``ad_num_ports``: Set bond attribute
+  - ``ad_partner_key``: Set bond attribute
+  - ``ad_partner_mac``: Set bond attribute
+  - ``ad_select``: Set bond attribute
+  - ``ad_user_port_key``: Set bond attribute
+  - ``all_slaves_active``: Set bond attribute
+  - ``arp_all_targets``: Set bond attribute
+  - ``arp_interval``: Set bond attribute
+  - ``arp_ip_target``: Set bond attribute
+  - ``arp_validate``: Set bond attribute
+  - ``downdelay``: Set bond attribute
+  - ``fail_over_mac``: Set bond attribute
+  - ``lacp_rate``: Set bond attribute
+  - ``lp_interval``: Set bond attribute
+  - ``miimon``: Set bond attribute
+  - ``mii_status``: Set bond attribute
+  - ``min_links``: Set bond attribute
+  - ``mode``: Set bond attribute
+  - ``num_grat_arp``: Set bond attribute
+  - ``num_unsol_na``: Set bond attribute
+  - ``packets_per_slave``: Set bond attribute
+  - ``primary``: Set bond attribute
+  - ``primary_reselect``: Set bond attribute
+  - ``queue_id``: Set bond attribute
+  - ``resend_igmp``: Set bond attribute
+  - ``slaves``: Set bond attribute
+  - ``tlb_dynamic_lb``: Set bond attribute
+  - ``updelay``: Set bond attribute
+  - ``use_carrier``: Set bond attribute
+  - ``xmit_hash_policy``: Set bond attribute
+
+**Bond Example**::
+
+   network:
+    version: 1
+    config:
+      # Simple network adapter
+      - type: physical
+        name: interface0
+        mac_address: 00:11:22:33:44:55
+      # 10G pair
+      - type: physical
+        name: gbe0
+        mac_address: cd:11:22:33:44:00
+      - type: physical
+        name: gbe1
+        mac_address: cd:11:22:33:44:02
+      - type: bond
+        name: bond0
+        bond_interfaces:
+          - gbe0
+          - gbe1
+        params:
+          bond-mode: active-backup
+
+Bridge
+~~~~~~
+Type ``bridge`` requires the following keys:
+
+- ``name``: Set the name of the bridge.
+- ``bridge_interfaces``: Specify the ports of a bridge via their ``name``.  This list may be empty.
+- ``params``:  A list of bridge params.  For more details, please read the bridge-utils-interfaces manpage.
+
+Valid keys are:
+
+  - ``bridge_ageing``: Set the bridge's ageing value.
+  - ``bridge_bridgeprio``: Set the bridge device network priority.
+  - ``bridge_fd``: Set the bridge's forward delay.
+  - ``bridge_hello``: Set the bridge's hello value.
+  - ``bridge_hw``: Set the bridge's MAC address.
+  - ``bridge_maxage``: Set the bridge's maxage value.
+  - ``bridge_maxwait``:  Set how long network scripts should wait for the bridge to be up.
+  - ``bridge_pathcost``:  Set the cost of a specific port on the bridge.
+  - ``bridge_portprio``:  Set the priority of a specific port on the bridge.
+  - ``bridge_ports``:  List of devices that are part of the bridge.
+  - ``bridge_stp``:  Set spanning tree protocol on or off.
+  - ``bridge_waitport``: Set amount of time in seconds to wait on specific ports to become available.
+
+
+**Bridge Example**::
+
+   network:
+    version: 1
+    config:
+      # Simple network adapter
+      - type: physical
+        name: interface0
+        mac_address: 00:11:22:33:44:55
+      # Second nic with Jumbo frames
+      - type: physical
+        name: jumbo0
+        mac_address: aa:11:22:33:44:55
+        mtu: 9000
+      - type: bridge
+        name: br0
+        bridge_interfaces:
+          - jumbo0
+        params:
+          bridge_ageing: 250
+		  bridge_bridgeprio: 22
+		  bridge_fd: 1
+          bridge_hello: 1
+          bridge_maxage: 10
+          bridge_maxwait: 0
+          bridge_pathcost:
+            - jumbo0 75
+          bridge_pathprio:
+            - jumbo0 28
+          bridge_stp: 'off'
+          bridge_maxwait:
+            - jumbo0 0
+
+
+VLAN
+~~~~
+Type ``vlan`` requires the following keys:
+
+- ``name``: Set the name of the VLAN
+- ``vlan_link``: Specify the underlying link via its ``name``.
+- ``vlan_id``: Specify the VLAN numeric id.
+
+**VLAN Example**::
+
+   network:
+     version: 1
+     config:
+       # Physical interfaces.
+       - type: physical
+         name: eth0
+         mac_address: "c0:d6:9f:2c:e8:80"
+       # VLAN interface.
+       - type: vlan
+         name: eth0.101
+         vlan_link: eth0
+         vlan_id: 101
+         mtu: 1500
+
+Nameserver
+~~~~~~~~~~
+
+Users can specify a ``nameserver`` type.  Nameserver dictionaries include
+the following keys:
+
+- ``address``: List of IPv4 or IPv6 address of nameservers.
+- ``search``: List of of hostnames to include in the resolv.conf search path.
+
+**Nameserver Example**::
+
+  network:
+    version: 1
+    config:
+      - type: physical
+        name: interface0
+        mac_address: 00:11:22:33:44:55
+        subnets:
+           - type: static
+             address: 192.168.23.14/27
+             gateway: 192.168.23.1
+      - type: nameserver:
+        address:
+          - 192.168.23.2
+          - 8.8.8.8
+        search:
+          - exemplary
+
+
+
+Route
+~~~~~
+
+Users can include static routing information as well.  A ``route`` dictionary
+has the following keys:
+
+- ``destination``: IPv4 network address with CIDR netmask notation.
+- ``gateway``: IPv4 gateway address with CIDR netmask notation.
+- ``metric``: Integer which sets the network metric value for this route.
+
+**Route Example**::
+
+  network:
+    version: 1
+    config:
+      - type: physical
+        name: interface0
+        mac_address: 00:11:22:33:44:55
+        subnets:
+           - type: static
+             address: 192.168.23.14/24
+             gateway: 192.168.23.1
+      - type: route
+        destination: 192.168.24.0/24
+        gateway: 192.168.24.1
+        metric: 3
+
+Subnet/IP
+~~~~~~~~~
+
+For any network device (one of the Config Types) users can define a list of
+``subnets`` which contain ip configuration dictionaries.  Multiple subnet
+entries will create interface alias allowing a single interface to use different
+ip configurations.
+
+Valid keys for for ``subnets`` include the following:
+
+- ``type``: Specify the subnet type.
+- ``control``: Specify manual, auto or hotplug.  Indicates how the interface will be handled during boot.
+- ``address``: IPv4 or IPv6 address.  It may include CIDR netmask notation.
+- ``netmask``: IPv4 subnet mask in dotted format or CIDR notation.
+- ``gateway``: IPv4 address of the default gateway for this subnet.
+- ``dns_nameserver``: Specify a list of IPv4 dns server IPs to end up in resolv.conf.
+- ``dns_search``: Specify a list of search paths to be included in resolv.conf.
+- ``routes``:  Specify a list of routes for a given interface
+
+
+Subnet types are one of the following:
+
+- ``dhcp4``: Configure this interface with IPv4 dhcp.
+- ``dhcp``: Alias for ``dhcp4``
+- ``dhcp6``: Configure this interface with IPv6 dhcp.
+- ``static``: Configure this interface with a static IPv4.
+- ``static6``: Configure this interface with a static IPv6 .
+
+When making use of ``dhcp`` types, no additional configuration is needed in the
+subnet dictionary.
+
+
+**Subnet DHCP Example**::
+
+   network:
+     version: 1
+     config:
+       - type: physical
+         name: interface0
+         mac_address: 00:11:22:33:44:55
+         subnets:
+           - type: dhcp
+
+
+**Subnet Static Example**::
+
+   network:
+     version: 1
+     config:
+       - type: physical
+         name: interface0
+         mac_address: 00:11:22:33:44:55
+         subnets:
+           - type: static
+             address: 192.168.23.14/27
+             gateway: 192.168.23.1
+             dns_nameservers:
+               - 192.168.23.2
+               - 8.8.8.8
+             dns_search:
+               - exemplary.maas
+
+The following will result in an ``interface0`` using DHCP and ``interface0:1``
+using the static subnet configuration.
+
+**Multiple subnet Example**::
+
+   network:
+     version: 1
+     config:
+       - type: physical
+         name: interface0
+         mac_address: 00:11:22:33:44:55
+         subnets:
+           - type: dhcp
+           - type: static
+             address: 192.168.23.14/27
+             gateway: 192.168.23.1
+             dns_nameservers:
+               - 192.168.23.2
+               - 8.8.8.8
+             dns_search:
+               - exemplary
+
+**Subnet with routes Example**::
+
+   network:
+     version: 1
+     config:
+       - type: physical
+         name: interface0
+         mac_address: 00:11:22:33:44:55
+         subnets:
+           - type: dhcp
+           - type: static
+             address: 10.184.225.122
+             netmask: 255.255.255.252
+             routes:
+               - gateway: 10.184.225.121
+                 netmask: 255.240.0.0
+                 network: 10.176.0.0
+               - gateway: 10.184.225.121
+                 netmask: 255.240.0.0
+                 network: 10.208.0.0
+
+
+Multi-layered configurations
+----------------------------
+
+Complex networking sometimes uses layers of configuration.  The syntax allows
+users to build those layers one at a time.  All of the virtual network devices
+supported allow specifying an underlying device by their ``name`` value.
+
+**Bonded VLAN Example**::
+
+  network:
+    version: 1
+    config:
+      # 10G pair
+      - type: physical
+        name: gbe0
+        mac_address: cd:11:22:33:44:00
+      - type: physical
+        name: gbe1
+        mac_address: cd:11:22:33:44:02
+      # Bond.
+      - type: bond
+        name: bond0
+        bond_interfaces:
+          - gbe0
+          - gbe1
+        params:
+          bond-mode: 802.3ad
+          bond-lacp-rate: fast
+      # A Bond VLAN.
+      - type: vlan
+          name: bond0.200
+          vlan_link: bond0
+          vlan_id: 200
+          subnets:
+              - type: dhcp4
+
+More Examples
+-------------
+Some more examples to explore the various options available.
+
+**Multiple VLAN example**::
+
+  network:
+    version: 1
+    config:
+    - id: eth0
+      mac_address: d4:be:d9:a8:49:13
+      mtu: 1500
+      name: eth0
+      subnets:
+      - address: 10.245.168.16/21
+        dns_nameservers:
+        - 10.245.168.2
+        gateway: 10.245.168.1
+        type: static
+      type: physical
+    - id: eth1
+      mac_address: d4:be:d9:a8:49:15
+      mtu: 1500
+      name: eth1
+      subnets:
+      - address: 10.245.188.2/24
+        dns_nameservers: []
+        type: static
+      type: physical
+    - id: eth1.2667
+      mtu: 1500
+      name: eth1.2667
+      subnets:
+      - address: 10.245.184.2/24
+        dns_nameservers: []
+        type: static
+      type: vlan
+      vlan_id: 2667
+      vlan_link: eth1
+    - id: eth1.2668
+      mtu: 1500
+      name: eth1.2668
+      subnets:
+      - address: 10.245.185.1/24
+        dns_nameservers: []
+        type: static
+      type: vlan
+      vlan_id: 2668
+      vlan_link: eth1
+    - id: eth1.2669
+      mtu: 1500
+      name: eth1.2669
+      subnets:
+      - address: 10.245.186.1/24
+        dns_nameservers: []
+        type: static
+      type: vlan
+      vlan_id: 2669
+      vlan_link: eth1
+    - id: eth1.2670
+      mtu: 1500
+      name: eth1.2670
+      subnets:
+      - address: 10.245.187.2/24
+        dns_nameservers: []
+        type: static
+      type: vlan
+      vlan_id: 2670
+      vlan_link: eth1
+    - address: 10.245.168.2
+      search:
+      - dellstack
+      type: nameserver
+
+.. vi: textwidth=78
diff --git a/doc/rtd/topics/network-config-format-v2.rst b/doc/rtd/topics/network-config-format-v2.rst
new file mode 100644
index 0000000..335d236
--- /dev/null
+++ b/doc/rtd/topics/network-config-format-v2.rst
@@ -0,0 +1,503 @@
+.. _network_config_v2:
+
+Networking Config Version 2
+===========================
+
+Cloud-init's support for Version 2 network config is a subset of the
+version 2 format defined for the `netplan`_ tool.  Cloud-init supports
+both reading and writing of Version 2; the latter support requires a
+distro with `netplan`_ present.
+
+The ``network`` key has at least two required elements.  First
+it must include ``version: 2``  and one or more of possible device
+``types``..
+
+Cloud-init will read this format from system config.
+For example the following could be present in
+``/etc/cloud/cloud.cfg.d/custom-networking.cfg``:
+
+  network:
+    version: 2
+    ethernets: []
+
+It may also be provided in other locations including the
+:ref:`datasource_nocloud`, see :ref:`default_behavior` for other places.
+
+Supported device ``types`` values are as follows:
+
+- Ethernets (``ethernets``)
+- Bonds (``bonds``)
+- Bridges (``bridges``)
+- VLANs (``vlans``)
+
+Each type block contains device definitions as a map where the keys (called
+"configuration IDs"). Each entry under the ``types`` may include IP and/or
+device configuration.
+
+Cloud-init does not current support ``wifis`` type that is present in native
+`netplan`_.
+
+
+Device configuration IDs
+------------------------
+
+The key names below the per-device-type definition maps (like ``ethernets:``)
+are called "ID"s. They must be unique throughout the entire set of
+configuration files. Their primary purpose is to serve as anchor names for
+composite devices, for example to enumerate the members of a bridge that is
+currently being defined.
+
+There are two physically/structurally different classes of device definitions,
+and the ID field has a different interpretation for each:
+
+Physical devices
+
+:   (Examples: ethernet, wifi) These can dynamically come and go between
+    reboots and even during runtime (hotplugging). In the generic case, they
+    can be selected by ``match:`` rules on desired properties, such as name/name
+    pattern, MAC address, driver, or device paths. In general these will match
+    any number of devices (unless they refer to properties which are unique
+    such as the full path or MAC address), so without further knowledge about
+    the hardware these will always be considered as a group.
+
+    It is valid to specify no match rules at all, in which case the ID field is
+    simply the interface name to be matched. This is mostly useful if you want
+    to keep simple cases simple, and it's how network device configuration has
+    been done for a long time.
+
+    If there are ``match``: rules, then the ID field is a purely opaque name
+    which is only being used  for references from definitions of compound
+    devices in the config.
+
+Virtual devices
+
+:  (Examples: veth, bridge, bond) These are fully under the control of the
+   config file(s) and the network stack. I. e. these devices are being created
+   instead of matched. Thus ``match:`` and ``set-name:`` are not applicable for
+   these, and the ID field is the name of the created virtual device.
+
+Common properties for physical device types
+-------------------------------------------
+
+**match**: *<(mapping)>*
+
+This selects a subset of available physical devices by various hardware
+properties. The following configuration will then apply to all matching
+devices, as soon as they appear. *All* specified properties must match.
+The following properties for creating matches are supported:
+
+**name**:  *<(scalar)>*
+
+Current interface name. Globs are supported, and the primary use case
+for matching on names, as selecting one fixed name can be more easily
+achieved with having no ``match:`` at all and just using the ID (see
+above). Note that currently only networkd supports globbing,
+NetworkManager does not.
+
+**macaddress**: *<(scalar)>*
+
+Device's MAC address in the form "XX:XX:XX:XX:XX:XX". Globs are not allowed.
+
+**driver**: *<(scalar)>*
+
+Kernel driver name, corresponding to the ``DRIVER`` udev property.  Globs are
+supported. Matching on driver is *only* supported with networkd.
+
+**Examples**::
+
+  # all cards on second PCI bus
+  match:
+    name: enp2*
+
+  # fixed MAC address
+  match:
+    macaddress: 11:22:33:AA:BB:FF
+
+  # first card of driver ``ixgbe``
+  match:
+    driver: ixgbe
+    name: en*s0
+
+**set-name**: *<(scalar)>*
+
+When matching on unique properties such as path or MAC, or with additional
+assumptions such as "there will only ever be one wifi device",
+match rules can be written so that they only match one device. Then this
+property can be used to give that device a more specific/desirable/nicer
+name than the default from udev’s ifnames.  Any additional device that
+satisfies the match rules will then fail to get renamed and keep the
+original kernel name (and dmesg will show an error).
+
+**wakeonlan**: *<(bool)>*
+
+Enable wake on LAN. Off by default.
+
+
+Common properties for all device types
+--------------------------------------
+
+**renderer**: *<(scalar)>*
+
+Use the given networking backend for this definition. Currently supported are
+``networkd`` and ``NetworkManager``. This property can be specified globally
+in ``networks:``, for a device type (in e. g. ``ethernets:``) or
+for a particular device definition. Default is ``networkd``.
+
+.. note::
+
+  Cloud-init only supports networkd backend if rendering version2 config
+  to the instance.
+
+**dhcp4**: *<(bool)>*
+
+Enable DHCP for IPv4. Off by default.
+
+**dhcp6**: *<(bool)>*
+
+Enable DHCP for IPv6. Off by default.
+
+**addresses**: *<(sequence of scalars)>*
+
+Add static addresses to the interface in addition to the ones received
+through DHCP or RA. Each sequence entry is in CIDR notation, i. e. of the
+form ``addr/prefixlen`` . ``addr`` is an IPv4 or IPv6 address as recognized
+by ``inet_pton``(3) and ``prefixlen`` the number of bits of the subnet.
+
+Example: ``addresses: [192.168.14.2/24, 2001:1::1/64]``
+
+**gateway4**: or **gateway6**: *<(scalar)>*
+
+Set default gateway for IPv4/6, for manual address configuration. This
+requires setting ``addresses`` too. Gateway IPs must be in a form
+recognized by ``inet_pton(3)``
+
+Example for IPv4: ``gateway4: 172.16.0.1``
+Example for IPv6: ``gateway6: 2001:4::1``
+
+**nameservers**: *<(mapping)>*
+
+Set DNS servers and search domains, for manual address configuration. There
+are two supported fields: ``addresses:`` is a list of IPv4 or IPv6 addresses
+similar to ``gateway*``, and ``search:`` is a list of search domains.
+
+Example: ::
+
+  nameservers:
+    search: [lab, home]
+    addresses: [8.8.8.8, FEDC::1]
+
+**routes**: *<(sequence of mapping)>*
+
+Add device specific routes.  Each mapping includes a ``to``, ``via`` key
+with an IPv4 or IPv6 address as value.  ``metric`` is an optional value.
+
+Example: ::
+
+  routes:
+   - to: 0.0.0.0/0
+     via: 10.23.2.1
+     metric: 3
+
+Ethernets
+~~~~~~~~~
+Ethernet device definitions do not support any specific properties beyond the
+common ones described above.
+
+Bonds
+~~~~~
+
+**interfaces** *<(sequence of scalars)>*
+
+All devices matching this ID list will be added to the bond.
+
+Example: ::
+
+  ethernets:
+    switchports:
+      match: {name: "enp2*"}
+  [...]
+  bonds:
+    bond0:
+      interfaces: [switchports]
+
+**parameters**: *<(mapping)>*
+
+Customization parameters for special bonding options.  Time values are specified
+in seconds unless otherwise specified.
+
+**mode**: *<(scalar)>*
+
+Set the bonding mode used for the interfaces. The default is
+``balance-rr`` (round robin). Possible values are ``balance-rr``,
+``active-backup``, ``balance-xor``, ``broadcast``, ``802.3ad``,
+``balance-tlb``, and ``balance-alb``.
+
+**lacp-rate**: *<(scalar)>*
+
+Set the rate at which LACPDUs are transmitted. This is only useful
+in 802.3ad mode. Possible values are ``slow`` (30 seconds, default),
+and ``fast`` (every second).
+
+**mii-monitor-interval**: *<(scalar)>*
+
+Specifies the interval for MII monitoring (verifying if an interface
+of the bond has carrier). The default is ``0``; which disables MII
+monitoring.
+
+**min-links**: *<(scalar)>*
+
+The minimum number of links up in a bond to consider the bond
+interface to be up.
+
+**transmit-hash-policy**: <*(scalar)>*
+
+Specifies the transmit hash policy for the selection of slaves. This
+is only useful in balance-xor, 802.3ad and balance-tlb modes.
+Possible values are ``layer2``, ``layer3+4``, ``layer2+3``,
+``encap2+3``, and ``encap3+4``.
+
+**ad-select**: <*(scalar)>*
+
+Set the aggregation selection mode. Possible values are ``stable``,
+``bandwidth``, and ``count``. This option is only used in 802.3ad mode.
+
+**all-slaves-active**: <*(bool)>*
+
+If the bond should drop duplicate frames received on inactive ports,
+set this option to ``false``. If they should be delivered, set this
+option to ``true``. The default value is false, and is the desirable
+behavior in most situations.
+
+**arp-interval**: <*(scalar)>*
+
+Set the interval value for how frequently ARP link monitoring should
+happen. The default value is ``0``, which disables ARP monitoring.
+
+**arp-ip-targets**: <*(sequence of scalars)>*
+
+IPs of other hosts on the link which should be sent ARP requests in
+order to validate that a slave is up. This option is only used when
+``arp-interval`` is set to a value other than ``0``. At least one IP
+address must be given for ARP link monitoring to function. Only IPv4
+addresses are supported. You can specify up to 16 IP addresses. The
+default value is an empty list.
+
+**arp-validate**: <*(scalar)>*
+
+Configure how ARP replies are to be validated when using ARP link
+monitoring. Possible values are ``none``, ``active``, ``backup``,
+and ``all``.
+
+**arp-all-targets**: <*(scalar)>*
+
+Specify whether to use any ARP IP target being up as sufficient for
+a slave to be considered up; or if all the targets must be up. This
+is only used for ``active-backup`` mode when ``arp-validate`` is
+enabled. Possible values are ``any`` and ``all``.
+
+**up-delay**: <*(scalar)>*
+
+Specify the delay before enabling a link once the link is physically
+up. The default value is ``0``.
+
+**down-delay**: <*(scalar)>*
+
+Specify the delay before disabling a link once the link has been
+lost. The default value is ``0``.
+
+**fail-over-mac-policy**: <*(scalar)>*
+
+Set whether to set all slaves to the same MAC address when adding
+them to the bond, or how else the system should handle MAC addresses.
+The possible values are ``none``, ``active``, and ``follow``.
+
+**gratuitious-arp**: <*(scalar)>*
+
+Specify how many ARP packets to send after failover. Once a link is
+up on a new slave, a notification is sent and possibly repeated if
+this value is set to a number greater than ``1``. The default value
+is ``1`` and valid values are between ``1`` and ``255``. This only
+affects ``active-backup`` mode.
+
+**packets-per-slave**: <*(scalar)>*
+
+In ``balance-rr`` mode, specifies the number of packets to transmit
+on a slave before switching to the next. When this value is set to
+``0``, slaves are chosen at random. Allowable values are between
+``0`` and ``65535``. The default value is ``1``. This setting is
+only used in ``balance-rr`` mode.
+
+**primary-reselect-policy**: <*(scalar)>*
+
+Set the reselection policy for the primary slave. On failure of the
+active slave, the system will use this policy to decide how the new
+active slave will be chosen and how recovery will be handled. The
+possible values are ``always``, ``better``, and ``failure``.
+
+**learn-packet-interval**: <*(scalar)>*
+
+Specify the interval between sending learning packets to each slave.
+The value range is between ``1`` and ``0x7fffffff``. The default
+value is ``1``. This option only affects ``balance-tlb`` and
+``balance-alb`` modes.
+
+
+Bridges
+~~~~~~~
+
+**interfaces**: <*(sequence of scalars)>*
+
+All devices matching this ID list will be added to the bridge.
+
+Example: ::
+
+  ethernets:
+    switchports:
+      match: {name: "enp2*"}
+  [...]
+  bridges:
+    br0:
+      interfaces: [switchports]
+
+**parameters**: <*(mapping)>*
+
+Customization parameters for special bridging options.  Time values are specified
+in seconds unless otherwise specified.
+
+**ageing-time**: <*(scalar)>*
+
+Set the period of time to keep a MAC address in the forwarding
+database after a packet is received.
+
+**priority**: <*(scalar)>*
+
+Set the priority value for the bridge. This value should be an
+number between ``0`` and ``65535``. Lower values mean higher
+priority. The bridge with the higher priority will be elected as
+the root bridge.
+
+**forward-delay**: <*(scalar)>*
+
+Specify the period of time the bridge will remain in Listening and
+Learning states before getting to the Forwarding state. This value
+should be set in seconds for the systemd backend, and in milliseconds
+for the NetworkManager backend.
+
+**hello-time**: <*(scalar)>*
+
+Specify the interval between two hello packets being sent out from
+the root and designated bridges. Hello packets communicate
+information about the network topology.
+
+**max-age**: <*(scalar)>*
+
+Set the maximum age of a hello packet. If the last hello packet is
+older than that value, the bridge will attempt to become the root
+bridge.
+
+**path-cost**: <*(scalar)>*
+
+Set the cost of a path on the bridge. Faster interfaces should have
+a lower cost. This allows a finer control on the network topology
+so that the fastest paths are available whenever possible.
+
+**stp**: <*(bool)>*
+
+Define whether the bridge should use Spanning Tree Protocol. The
+default value is "true", which means that Spanning Tree should be
+used.
+
+
+VLANs
+~~~~~
+
+**id**: <*(scalar)>*
+
+VLAN ID, a number between 0 and 4094.
+
+**link**: <*(scalar)>*
+
+ID of the underlying device definition on which this VLAN gets
+created.
+
+Example: ::
+
+  ethernets:
+    eno1: {...}
+  vlans:
+    en-intra:
+      id: 1
+      link: eno1
+      dhcp4: yes
+    en-vpn:
+      id: 2
+      link: eno1
+      address: ...
+
+
+Examples
+--------
+Configure an ethernet device with networkd, identified by its name, and enable
+DHCP: ::
+
+  network:
+    version: 2
+    ethernets:
+      eno1:
+        dhcp4: true
+
+This is a complex example which shows most available features: ::
+
+  network:
+    version: 2
+    ethernets:
+      # opaque ID for physical interfaces, only referred to by other stanzas
+      id0:
+        match:
+          macaddress: 00:11:22:33:44:55
+        wakeonlan: true
+        dhcp4: true
+        addresses:
+          - 192.168.14.2/24
+          - 2001:1::1/64
+        gateway4: 192.168.14.1
+        gateway6: 2001:1::2
+        nameservers:
+          search: [foo.local, bar.local]
+          addresses: [8.8.8.8]
+      lom:
+        match:
+          driver: ixgbe
+        # you are responsible for setting tight enough match rules
+        # that only match one device if you use set-name
+        set-name: lom1
+        dhcp6: true
+      switchports:
+        # all cards on second PCI bus; unconfigured by themselves, will be added
+        # to br0 below
+        match:
+          name: enp2*
+        mtu: 1280
+    bonds:
+      bond0:
+        interfaces: [id0, lom]
+    bridges:
+      # the key name is the name for virtual (created) interfaces; no match: and
+      # set-name: allowed
+      br0:
+        # IDs of the components; switchports expands into multiple interfaces
+        interfaces: [wlp1s0, switchports]
+        dhcp4: true
+    vlans:
+      en-intra:
+        id: 1
+        link: id0
+        dhcp4: yes
+    # static routes
+    routes:
+     - to: 0.0.0.0/0
+       via: 11.0.0.1
+       metric: 3
+
+.. _netplan: https://launchpad.net/netplan
+.. vi: textwidth=78
diff --git a/doc/rtd/topics/network-config.rst b/doc/rtd/topics/network-config.rst
new file mode 100644
index 0000000..cd2480a
--- /dev/null
+++ b/doc/rtd/topics/network-config.rst
@@ -0,0 +1,252 @@
+*********************
+Network Configuration
+*********************
+
+- Default Behavior
+- Disabling Network Configuration
+- Fallback Networking
+- Network Configuration Sources
+- Network Configuration Outputs
+- Network Output Policy
+- Network Configuration Tools
+- Examples
+
+.. _default_behavior:
+
+Default Behavior
+================
+
+`Cloud-init`_ 's searches for network configuration in order of increasing
+precedence; each item overriding the previous.
+
+**Datasource**
+
+For example, OpenStack may provide network config in the MetaData Service.
+
+**System Config**
+
+A ``network:`` entry in /etc/cloud/cloud.cfg.d/* configuration files.
+
+**Kernel Command Line**
+
+``ip=`` or ``network-config=<YAML config string>``
+
+User-data cannot change an instance's network configuration.  In the absense
+of network configuration in any of the above sources , `Cloud-init`_ will
+write out a network configuration that will issue a DHCP request on a "first"
+network interface.
+
+
+Disabling Network Configuration
+===============================
+
+Users may disable `Cloud-init`_ 's network configuration capability and rely
+on other methods, such as embedded configuration or other customizations.
+
+`Cloud-init`_ supports the following methods for disabling cloud-init.
+
+
+**Kernel Command Line**
+
+`Cloud-init`_ will check for a parameter ``network-config`` and the
+value is expected to be YAML string in the :ref:`network_config_v1` format.
+The YAML string may optionally be ``Base64`` encoded, and optionally
+compressed with ``gzip``.
+
+Example disabling kernel command line entry: ::
+
+  network-config={config: disabled}
+
+
+**cloud config**
+
+In the combined cloud-init configuration dictionary. ::
+
+  network:
+    config: disabled
+
+If `Cloud-init`_ 's networking config has not been disabled, and
+no other network information is found, then it will proceed
+to generate a fallback networking configuration.
+
+
+Fallback Network Configuration
+==============================
+
+`Cloud-init`_ will attempt to determine which of any attached network devices
+is most likely to have a connection and then generate a network
+configuration to issue a DHCP request on that interface.
+
+`Cloud-init`_ runs during early boot and does not expect composed network
+devices (such as Bridges) to be available.  `Cloud-init`_ does not consider
+the following interface devices as likely 'first' network interfaces for
+fallback configuration; they are filtered out from being selected.
+
+- **loopback**: ``name=lo``
+- **Virtual Ethernet**: ``name=veth*``
+- **Software Bridges**: ``type=bridge``
+- **Software VLANs**: ``type=vlan``
+
+
+`Cloud-init`_ will prefer network interfaces that indicate they are connected
+via the Linux ``carrier`` flag being set.  If no interfaces are marked
+connected, then all unfiltered interfaces are potential connections.
+
+Of the potential interfaces, `Cloud-init`_ will attempt to pick the "right"
+interface given the information it has available.
+
+Finally after selecting the "right" interface, a configuration is
+generated and applied to the system.
+
+
+Network Configuration Sources
+=============================
+
+`Cloud-init`_ accepts a number of different network configuration formats in
+support of different cloud substrates.  The Datasource for these clouds in
+`Cloud-init`_ will detect and consume Datasource-specific network configuration
+formats for use when writing an instance's network configuration.
+
+The following Datasources optionally provide network configuration:
+
+- :ref:`datasource_config_drive`
+
+  - `OpenStack Metadata Service Network`_
+  - :ref:`network_config_eni`
+
+- :ref:`datasource_digital_ocean`
+
+  - `DigitalOcean JSON metadata`_
+
+- :ref:`datasource_nocloud`
+
+  - :ref:`network_config_v1`
+  - :ref:`network_config_v2`
+  - :ref:`network_config_eni`
+
+- :ref:`datasource_opennebula`
+
+  - :ref:`network_config_eni`
+
+- :ref:`datasource_openstack`
+
+  - :ref:`network_config_eni`
+  - `OpenStack Metadata Service Network`_
+
+- :ref:`datasource_smartos`
+
+  - `SmartOS JSON Metadata`_
+
+For more information on network configuration formats
+
+.. toctree::
+  :maxdepth: 1
+
+  network-config-format-eni.rst
+  network-config-format-v1.rst
+  network-config-format-v2.rst
+
+
+Network Configuration Outputs
+=============================
+
+`Cloud-init`_ converts various forms of user supplied or automatically
+generated configuration into an internal network configuration state. From
+this state `Cloud-init`_ delegates rendering of the configuration to Distro
+supported formats.  The following ``renderers`` are supported in cloud-init:
+
+- **ENI**
+
+/etc/network/interfaces or ``ENI`` is supported by the ``ifupdown`` package
+found in Ubuntu and Debian.
+
+- **Netplan**
+
+Since Ubuntu 16.10, codename Yakkety, the ``netplan`` project has been an
+optional network configuration tool which consumes :ref:`network_config_v2`
+input and renders network configuration for supported backends such as
+``systemd-networkd`` and ``NetworkManager``.
+
+- **Sysconfig**
+
+Sysconfig format is used by RHEL, CentOS, Fedora and other derivatives.
+
+
+Network Output Policy
+=====================
+
+The default policy for selecting a network ``renderer`` in order of preference
+is as follows:
+
+- ENI
+- Sysconfig
+- Netplan
+
+When applying the policy, `Cloud-init`_ checks if the current instance has the
+correct binaries and paths to support the renderer.  The first renderer that
+can be used is selected.  Users may override the network renderer policy by
+supplying an updated configuration in cloud-config. ::
+
+  system_info:
+    network:
+      renderers: ['netplan', 'eni', 'sysconfig']
+
+
+Network Configuration Tools
+===========================
+
+`Cloud-init`_ contains one tool used to test input/output conversion between
+formats.  The ``tools/net-convert.py`` in the `Cloud-init`_ source repository
+is helpful for examining expected output for a given input format.
+
+CLI Interface :
+
+.. code-block:: bash
+
+  % tools/net-convert.py --help
+  usage: net-convert.py [-h] --network-data PATH --kind
+                        {eni,network_data.json,yaml} -d PATH [-m name,mac]
+                        --output-kind {eni,netplan,sysconfig}
+
+  optional arguments:
+    -h, --help            show this help message and exit
+    --network-data PATH, -p PATH
+    --kind {eni,network_data.json,yaml}, -k {eni,network_data.json,yaml}
+    -d PATH, --directory PATH
+                          directory to place output in
+    -m name,mac, --mac name,mac
+                          interface name to mac mapping
+    --output-kind {eni,netplan,sysconfig}, -ok {eni,netplan,sysconfig}
+
+
+Example output convertion V2 to sysconfig:
+
+.. code-block:: bash
+
+  % tools/net-convert.py --network-data v2.yaml --kind yaml --output-kind sysconfig -d target
+  % cat target/etc/sysconfig/network-scripts/ifcfg-eth*
+  # Created by cloud-init on instance boot automatically, do not edit.
+  #
+  BOOTPROTO=static
+  DEVICE=eth7
+  IPADDR=192.168.1.5/255.255.255.0
+  NM_CONTROLLED=no
+  ONBOOT=yes
+  TYPE=Ethernet
+  USERCTL=no
+  # Created by cloud-init on instance boot automatically, do not edit.
+  #
+  BOOTPROTO=dhcp
+  DEVICE=eth9
+  NM_CONTROLLED=no
+  ONBOOT=yes
+  TYPE=Ethernet
+  USERCTL=no
+
+
+.. _Cloud-init: https://launchpad.net/cloud-init
+.. _DigitalOcean JSON metadata: https://developers.digitalocean.com/documentation/metadata/#network-interfaces-index
+.. _OpenStack Metadata Service Network: https://specs.openstack.org/openstack/nova-specs/specs/liberty/implemented/metadata-service-network-info.html
+.. _SmartOS JSON Metadata: https://eng.joyent.com/mdata/datadict.html
+
+.. vi: textwidth=78