The YANG Development Kit (YDK) is a Software Development Kit that provides API's that are modeled in YANG. The main goal of YDK is to reduce the learning curve of YANG data models by expressing the model semantics in an API and abstracting protocol/encoding details. YDK is composed of a core package that defines services and providers, plus one or more module bundles that are based on YANG models. Each module bundle is generated using a bundle profile and the ydk-gen tool.

Linux

Ubuntu (Debian-based) - The following packages must be present in your system before installing YDK-Py:

$ sudo apt-get install python-pip zlib1g-dev python-lxml libxml2-dev libxslt1-dev python-dev

Centos (Fedora-based) - The following packages must be present in your system before installing YDK-Py:

$ sudo yum install epel-release
$ sudo yum install python-pip python-devel libxml2-devel libxslt-devel libcurl-devel libtool

Mac

It is recommended to install homebrew (http://brew.sh), homebrew python package and Xcode command line tools on your system before installing YDK-Py:

$ xcode-select --install
$ /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
$ brew install python pkg-config libssh xml2 curl pcre

Windows

It is recommended to install a python distribution like PythonXY on your system before installing YDK-Py

Python2.7 or Python 3.4

We recommend that you perform the installation under a Python virtual environment (virtualenv/virtualenvwrapper). To install support in your system, execute:

ydk-py$ pip install virtualenv virtualenvwrapper
ydk-py$ source /usr/local/bin/virtualenvwrapper.sh

In some systems (e.g. Debian-based Linux), you may need to install support for Python virtual environments as root:

ydk-py$ sudo pip install virtualenv virtualenvwrapper
ydk-py$ source /usr/local/bin/virtualenvwrapper.sh

At this point, create a new virtual environment:

ydk-py$ mkvirtualenv -p python2.7 ydk-py

Now you can install the core package:

(ydk-py)ydk-py$ cd core
(ydk-py)core$ python setup.py sdist
(ydk-py)core$ pip install dist/ydk*.gz

Once you have installed the core package, you can install one more model bundles. Note that some bundles have dependencies on other bundles. Those dependencies are already captured in the bundle package. To install the IETF bundle, execute:

(ydk-py)core$ cd ../ietf
(ydk-py)ietf$ python setup.py sdist
(ydk-py)ietf$ pip install dist/ydk*.gz

To install the OpenConfig bundle, execute:

(ydk-py)ietf$ cd ../openconfig
(ydk-py)openconfig$ python setup.py sdist
(ydk-py)openconfig$ pip install dist/ydk*.gz

To install the cisco-ios-xr bundle, execute:

(ydk-py)openconfig$ cd ../cisco-ios-xr
(ydk-py)cisco-ios-xr$ python setup.py sdist
(ydk-py)cisco-ios-xr$ pip install dist/ydk*.gz
(ydk-py)cisco-ios-xr$ cd ..

In this example, we set some BGP configuration using the OpenConfig model, the CRUD (Create/Read/Update/Delete) service and the NETCONF service provider. The example in this document is a simplified version of the more complete sample that is available in samples/bgp.py. That more complete sample can be run with the below steps:

(ydk-py)ydk-py$ cd core/samples
(ydk-py)samples$ ./bgp.py -h
Usage: bgp.py [-h | --help] [options]

Options:
-h, --help            show this help message and exit
-v VERSION, --version=VERSION
                    force NETCONF version 1.0 or 1.1
-u USERNAME, --user=USERNAME
-p PASSWORD, --password=PASSWORD
                    password
--proto=PROTO         Which transport protocol to use, one of ssh or tcp
--host=HOST           NETCONF agent hostname
--port=PORT           NETCONF agent SSH port

(ydk-py)samples$ ./bgp.py --host <ip-address-of-netconf-server> -u <username> -p <password> --port <port-number>

The first step in any application is to create a service provider instance. In this case, the NETCONF service provider (defined in ydk.providers.NetconfServiceProvider) is responsible for mapping between the CRUD service API and the underlying manageability protocol (NETCONF RPCs).

We instantiate an instance of the service provider that creates a NETCONF session to the machine with address 10.0.0.1 :

from ydk.providers import NetconfServiceProvider

sp_instance = NetconfServiceProvider(address='10.0.0.1',
                                     port=830,
                                     username='test',
                                     password='test',
                                     protocol = 'ssh')

After establishing the connection, we instantiate the entities and set some data. First, we import the types from the OpenConfig BGP module:

from ydk.models.openconfig import openconfig_bgp
from ydk.models.openconfig import openconfig_bgp_types

Next, create a BGP configuration object and set the attributes:

# create BGP object
bgp_cfg = openconfig_bgp.Bgp()

# set the Global AS
bgp_cfg.global_.config.as_ = 65001

# Create an AFI SAFI config
ipv4_afsf = bgp_cfg.global_.afi_safis.AfiSafi()
ipv4_afsf.afi_safi_name = openconfig_bgp_types.Ipv4Unicast()
ipv4_afsf.config.afi_safi_name = openconfig_bgp_types.Ipv4Unicast()
ipv4_afsf.config.enabled = True

# Add the AFI SAFI config to the global AFI SAFI list
bgp_cfg.global_.afi_safis.afi_safi.append(ipv4_afsf)

The CRUD service provides methods to create, read, update and delete entities on a device making use of the session provided by a service provider (NETCONF in this case). In order to use the CRUD service, we need to import the CRUDService class:

from ydk.services import CRUDService

Next, we instantiate the CRUD service:

crud_service = CRUDService()

Finally, we invoke the create method of the CRUDService class passing in the service provider instance and our entity (bgp_cfg):

try:
    crud_service.create(sp_instance, bgp_cfg)
except YPYError:

Note if there were any errors the above API will raise a YPYError exception.

YDK uses common Python logging. All modules are based on the "ydk" log:

import logging
log = logging.getLogger('ydk')
log.setLevel(logging.DEBUG)
ch = logging.StreamHandler()
log.addHandler(ch)

The current YDK release version is 0.5.3 (beta). YDK-Py is licensed under the Apache 2.0 License.

• Samples can be found under the samples directory
• API documentation can be found at http://ydk.cisco.com/py/docs
• Additional samples can be found at https://github.com/CiscoDevNet/ydk-py-samples
• For queries related to usage of the API, please join the YDK community at https://communities.cisco.com/community/developer/ydk