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Description:

libyang 3.0.1

Python CFFI bindings to libyang.

Installation
pip install libyang
This assumes libyang.so is installed in the system and that libyang.h is
available in the system include dirs.
You need the following system dependencies installed:

Python development headers
GCC
FFI development headers

On a Debian/Ubuntu system:
sudo apt-get install python3-dev gcc python3-cffi

Compatibility
The current version requires at least C libyang 2.25.
The last version of the bindings that works with C libyang 1.x is v1.7.0.

Compilation Flags
If libyang headers and libraries are installed in a non-standard location, you
can specify them with the LIBYANG_HEADERS and LIBYANG_LIBRARIES
variables. Additionally, for finer control, you may use LIBYANG_EXTRA_CFLAGS
and LIBYANG_EXTRA_LDFLAGS:
LIBYANG_HEADERS=/home/build/opt/ly/include \
LIBYANG_LIBRARIES=/home/build/opt/ly/lib \
LIBYANG_EXTRA_CFLAGS="-O3" \
LIBYANG_EXTRA_LDFLAGS="-rpath=/opt/ly/lib" \
pip install libyang

Examples

Schema Introspection
>>> 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.SList: 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.SLeaf: name string>
<libyang.schema.SContainer: udp-and-tcp>
>>> ctx.destroy()
>>>

Data Tree
>>> import libyang
>>> ctx = libyang.Context()
>>> module = ctx.parse_module_str('''
... module example {
... namespace "urn:example";
... prefix "ex";
... container data {
... list interface {
... key name;
... leaf name {
... type string;
... }
... leaf address {
... type string;
... }
... }
... leaf hostname {
... type string;
... }
... }
... }
... ''')
>>> print(module.print_mem('tree'))
module: example
+--rw data
+--rw interface* [name]
| +--rw name string
| +--rw address? string
+--rw hostname? string
>>> node = module.parse_data_dict({
... 'data': {
... 'hostname': 'foobar',
... 'interface': [
... {'name': 'eth0', 'address': '1.2.3.4/24'},
... {'name': 'lo', 'address': '127.0.0.1'},
... ],
... },
... })
>>> print(node.print_mem('xml', pretty=True))
<data xmlns="urn:example">
<interface>
<name>eth0</name>
<address>1.2.3.4/24</address>
</interface>
<interface>
<name>lo</name>
<address>127.0.0.1</address>
</interface>
<hostname>foobar</hostname>
</data>
>>> node.print_dict()
{'data': {'interface': [{'name': 'eth0', 'address': '1.2.3.4/24'}, {'name':
'lo', 'address': '127.0.0.1'}], 'hostname': 'foobar'}}
>>> node.free()
>>> ctx.destroy()
>>>
See the tests folder for more examples.

Contributing
This is an open source project and all contributions are welcome.

Issues
Please create new issues for any bug you discover at
https://github.com/CESNET/libyang-python/issues/new. It is not necessary to file
a bug if you are preparing a patch.

Pull Requests
Here are the steps for submitting a change in the code base:

Fork the repository: https://github.com/CESNET/libyang-python/fork
Clone your own fork into your development machine:
git clone https://github.com/<you>/libyang-python

Create a new branch named after what your are working on:
git checkout -b my-topic -t origin/master

Edit the code and call make format to ensure your modifications comply
with the coding style.
Your contribution must be licensed under the MIT License . At least one
copyright notice is expected in new files.

If you are adding a new feature or fixing a bug, please consider adding or
updating unit tests.
Before creating commits, run make lint and make tests to check if
your changes do not break anything. You can also run make which will run
both.
Once you are happy with your work, you can create a commit (or several
commits). Follow these general rules:

Address only one issue/topic per commit.
Describe your changes in imperative mood, e.g. “make xyzzy do frotz”
instead of “[This patch] makes xyzzy do frotz” or “[I] changed xyzzy to
do frotz”, as if you are giving orders to the codebase to change its
behaviour.
Limit the first line (title) of the commit message to 60 characters.
Use a short prefix for the commit title for readability with git log --oneline. Do not use the fix: nor feature: prefixes. See recent
commits for inspiration.
Only use lower case letters for the commit title except when quoting
symbols or known acronyms.
Use the body of the commit message to actually explain what your patch
does and why it is useful. Even if your patch is a one line fix, the
description is not limited in length and may span over multiple
paragraphs. Use proper English syntax, grammar and punctuation.
If you are fixing an issue, use appropriate Closes: <URL> or
Fixes: <URL> trailers.
If you are fixing a regression introduced by another commit, add a
Fixes: <COMMIT_ID> ("<TITLE>") trailer.
When in doubt, follow the format and layout of the recent existing
commits.
The following trailers are accepted in commits. If you are using multiple
trailers in a commit, it’s preferred to also order them according to this
list.

Closes: <URL>: close the referenced issue or pull request.
Fixes: <SHA> ("<TITLE>"): reference the commit that introduced
a regression.
Link: <URL>: any useful link to provide context for your commit.
Suggested-by
Requested-by
Reported-by
Co-authored-by
Tested-by
Reviewed-by
Acked-by
Signed-off-by: Compulsory!

There is a great reference for commit messages in the Linux kernel
documentation.
IMPORTANT: you must sign-off your work using git commit --signoff. Follow
the Linux kernel developer’s certificate of origin for more details. All
contributions are made under the MIT license. If you do not want to disclose
your real name, you may sign-off using a pseudonym. Here is an example:
Signed-off-by: Robin Jarry <robin@jarry.cc>

Push your topic branch in your forked repository:
git push origin my-topic
You should get a message from Github explaining how to create a new pull
request.

Wait for a reviewer to merge your work. If minor adjustments are requested,
use git commit --fixup $sha1 to make it obvious what commit you are
adjusting. If bigger changes are needed, make them in new separate commits.
Once the reviewer is happy, please use git rebase --autosquash to amend
the commits with their small fixups (if any), and git push --force on
your topic branch.

Thank you in advance for your contributions!