Overview
   
pyang is a YANG validator, transformator and code generator, written in python. It can be used to validate YANG modules for correctness, to transform YANG modules into other formats, and to write plugins to generate code from the modules.
    YANG (
    
     RFC 7950
    
    ) is a data modeling language for NETCONF (
    
     RFC 6241
    
    ), developed by the IETF
    
     NETMOD
    
    WG.
   
    Documentation
   
    See
    
     Documentation
    
    .
   
    Installation
   
- 
     
 1 PyPI
 
    Pyang can be installed from
    
     PyPI
    
    :
   
# pip install pyang
- 
     
 2 Source
 
git clone https://github.com/mbj4668/pyang.git cd pyang python setup.py install (this might require root access)
To install in a different location, run:
python setup.py install --prefix=/usr/local
    If you do this, it is recommended to set the environment variable
    
     YANG_INSTALL
    
    to the prefix directory. This ensures that pyang will find standard YANG modules. In addition, make sure that
    
     PYTHONPATH
    
    is set to something as follows:
   
export PYTHONPATH=/usr/local/lib/python2.7/site-packages
or whatever version of python you are running.
Run locally without installing
export PATH=`pwd`/bin:$PATH export MANPATH=`pwd`/man:$MANPATH export PYTHONPATH=`pwd`:$PYTHONPATH export YANG_MODPATH=`pwd`/modules:$YANG_MODPATH export PYANG_XSLT_DIR=`pwd`/xslt export PYANG_RNG_LIBDIR=`pwd`/schema
or:
source ./env.sh
    Compatibility
   
pyang is compatible with the following IETF RFCs:
- 
     
 RFC 6020: YANG – A Data Modeling Language for the Network Configuration Protocol (NETCONF)
 
- 
     
 RFC 6087: Guidelines for Authors and Reviewers of YANG Data Model Documents
 
- 
     
 RFC 6110: Mapping YANG to Document Schema Definition Languages and Validating NETCONF Content
 
- 
     
 RFC 6643: Translation of Structure of Management Information Version 2 (SMIv2) MIB Modules to YANG Modules
 
- 
     
 RFC 7950: The YANG 1.1 Data Modeling Languages
 
- 
     
 RFC 7952: Defining and Using Metadata with YANGs
 
- 
     
 RFC 8040: RESTCONF Protocols
 
- 
     
 RFC 8407: Guidelines for Authors and Reviewers of Documents Containing YANG Data Models
 
- 
     
 RFC 8791: YANG Data Structure Extensions
 
    Features
   
- Validate YANG modules.
- Convert YANG modules to YIN, and YIN to YANG.
- 
     Translate YANG data models to DSDL schemas, which can be used for validating various XML instance documents. See
 
 InstanceValidation
 
 .
- 
     Generate UML diagrams from YANG models. See
 
 UMLOutput
 
 for an example.
- 
     Generate compact tree representation of YANG models for quick visualization. See
 
 TreeOutput
 
 for an example.
- Generate a skeleton XML instance document from the data model.
- 
     Schema-aware translation of instance documents encoded in XML to JSON and vice-versa. See
 
 XmlJson
 
 .
- Plugin framework for simple development of other outputs, such as code generation.
    Usage
   
pyang -h
or
man pyang
    Code structure
   
- 
 bin/
 
 Executable scripts.
- 
 pyang/
 
 Contains the pyang library code.
- 
 pyang/
 
 init
 
 .py
 
 Initialization code for the pyang library.
- 
 pyang/context.py
 
 Defines the Context class, which represents a parsing session
- 
 pyang/repository.py
 
 Defines the Repository class, which is used to access modules.
- 
 pyang/syntax.py
 
 Generic syntax checking for YANG and YIN statements. Defines regular expressions for argument checking of core statements.
- 
 pyang/grammar.py
 
 Generic grammar for YANG and YIN. Defines chk_module_statements() which validates a parse tree according to the grammar.
- 
 pyang/statements.py
 
 Defines the generic Statement class and all validation code.
- 
 pyang/yang_parser.py
 
 YANG tokenizer and parser.
- 
 pyang/yin_parser.py
 
 YIN parser. Uses the expat library for XML parsing.
- 
 pyang/types.py
 
 Contains code for checking built-in types.
- 
 pyang/plugin.py
 
 Plugin API. Defines the class PyangPlugin which all plugins inherits from. All output handlers are written as plugins.
- 
 pyang/plugins/
 
 Directory where plugins can be installed. All plugins in this directory are automatically initialized when the library is initialized.
- 
 pyang/translators/
 
 Contains output plugins for YANG, YIN, and DSDL translation.
- 
 xslt
 
 Contains XSLT style sheets for generating RELAX NG, Schematron and DSRL schemas and validating instance documents. Also included is the free implementation of ISO Schematron by Rick Jelliffe from
 
 http://www.schematron.com/
 
 (files iso_schematron_skeleton_for_xslt1.xsl, iso_abstract_expand.xsl and iso_svrl_for_xslt1.xsl).
- 
 schema
 
 Contains RELAX NG schemas and pattern libraries.
 
