libyang-cffi

Python CFFI bindings to libyang.

Installation

pip install libyang

You need the following system dependencies installed:

• Python development headers
• GCC
• cmake (to build the libyang C code)
• Lib PCRE development headers (to build the libyang C code)

On a Debian/Ubuntu system:

sudo apt-get install python3-dev build-essential cmake libpcre3-dev

Note

By default, the C library will be compiled and statically linked with the python _libyang.so extension.

If you already have libyang.so installed on your system (with the development headers), you can link the python extension with it by exporting the LIBYANG_INSTALL=system variable when running pip:

LIBYANG_INSTALL=system pip install libyang

Examples

>>> import libyang
>>> ctx = libyang.Context('/usr/local/share/yang/modules')
>>> module = ctx.load_module('ietf-system')
>>> print(module)
module: ietf-system
  +--rw system
  |  +--rw contact?          string
  |  +--rw hostname?         ietf-inet-types:domain-name
  |  +--rw location?         string
  |  +--rw clock
  |  |  +--rw (timezone)?
  |  |     +--:(timezone-utc-offset)
  |  |        +--rw timezone-utc-offset?   int16
  |  +--rw dns-resolver
  |     +--rw search*    ietf-inet-types:domain-name
  |     +--rw server* [name]
  |     |  +--rw name          string
  |     |  +--rw (transport)
  |     |     +--:(udp-and-tcp)
  |     |        +--rw udp-and-tcp
  |     |           +--rw address    ietf-inet-types:ip-address
  |     +--rw options
  |        +--rw timeout?    uint8 <5>
  |        +--rw attempts?   uint8 <2>
  +--ro system-state
     +--ro platform
     |  +--ro os-name?      string
     |  +--ro os-release?   string
     |  +--ro os-version?   string
     |  +--ro machine?      string
     +--ro clock
        +--ro current-datetime?   ietf-yang-types:date-and-time
        +--ro boot-datetime?      ietf-yang-types:date-and-time

  rpcs:
    +---x set-current-datetime
    |  +---- input
    |     +---w current-datetime    ietf-yang-types:date-and-time
    +---x system-restart
    +---x system-shutdown

>>> xpath = '/ietf-system:system/ietf-system:dns-resolver/ietf-system:server'
>>> dnsserver = next(ctx.find_path(xpath))
>>> dnsserver
<libyang.schema.List: server [name]>
>>> print(dnsserver.description())
List of the DNS servers that the resolver should query.

When the resolver is invoked by a calling application, it
sends the query to the first name server in this list.  If
no response has been received within 'timeout' seconds,
the resolver continues with the next server in the list.
If no response is received from any server, the resolver
continues with the first server again.  When the resolver
has traversed the list 'attempts' times without receiving
any response, it gives up and returns an error to the
calling application.

Implementations MAY limit the number of entries in this
list.
>>> dnsserver.ordered()
True
>>> for node in dnsserver:
...     print(repr(node))
...
<libyang.schema.Leaf: name string>
<libyang.schema.Container: udp-and-tcp>