scrapli-netconf 2020.9.23

Netconf driver built on scrapli

scrapli_netconf

scrapli_netconf is a netconf driver built on top of scrapli. The purpose of scrapli_netconf is to provide a fast, flexible, thoroughly tested, well typed, well documented, simple API that supports both synchronous and asynchronous usage. Working together scrapli and scrapli_netconf aim to provide a consistent (as is practical) look and feel when automating devices over telnet, SSH, or netconf (over SSH).

scrapli_netconf aims to be fully RFC compliant at some point, but at the moment does not implement all netconf features/methods.

Table of Contents

• Quick Start Guide
  • Installation
  • A Simple Example
  • More Examples
  • Documentation
• scrapli_netconf: What is it
• Supported Platforms
• Advanced Installation
• Basic Usage
  • Picking the right Driver
  • Basic Driver Arguments
  • Opening and Closing a Connection
  • Get Config
  • Get
  • Lock and Unlock
  • Edit Config
  • Delete Config
  • Commit and Discard
  • RPC
• Advanced Usage
  • Capabilities
  • Datastores
• FAQ
• Linting and Testing

Quick Start Guide

Installation

In most cases installation via pip is the simplest and best way to install scrapli_netconf. See below or here for advanced installation details.

pip install scrapli-netconf

A Simple Example

from scrapli_netconf.driver import NetconfScrape

my_device = {
    "host": "172.18.0.13",
    "auth_username": "vrnetlab",
    "auth_password": "VR-netlab9",
    "auth_strict_key": False,
    "port": 830
}

conn = NetconfScrape(**my_device)
conn.open()
response = conn.get_config(source="running")
print(response.result)

$ python my_scrapli_script.py
<rpc-reply message-id="101">
 <data>
  <ssh>
   <server>
    <v2/>
    <netconf>830</netconf>
    <netconf-vrf-table>
     <vrf>
      <vrf-name>default</vrf-name>
      <enable/>
     </vrf>
    </netconf-vrf-table>
   </server>
  </ssh>
  <interface-configurations>
   <interface-configuration>
    <active>act</active>
    <interface-name>MgmtEth0/RP0/CPU0/0</interface-name>
<SNIP>
 </data>
</rpc-reply>

More Examples

• Basic Operations IOS-XR
• Basic Operations Junos
• Edit Config IOS-XR
• Asyncio Edit Config IOS-XR

Documentation

Documentation is auto-generated using pdoc3. Documentation is linted (see Linting and Testing section) via pydocstyle and darglint.

Documentation is hosted via GitHub Pages and can be found here. You can also view this readme as a web page here.

To regenerate documentation locally, use the following make command:

make docs

scrapli_netconf: What is it

scrapli_netconf is a library to help send or receive netconf messages to devices, specifically routers (though could be anything speaking netconf in theory).

Netconf is an IETF network management protocol that uses XML for message encoding, and SSH (or TLS, which is not supported by scrapli_netconf) for transport of messages. scrapli_netconf is simply an extension of the scrapli "screen scraping" library that adds proper message creation, framing, and validation to allow for scrapli to be used as a netconf client.

scrapli_netconf adds new drivers (NetconfScrape and AsyncNetconfScrape), new transports (NetconfTransport and AsyncNetconfTransport), and new channels (NetconfChannel and AsyncNetconfChannel) all of which inherit from , and build on, the core scrapli components. scrapli_netconf also includes an extension of the Response object -- aptly named NetconfResponse that adds netconf-specific data to the existing object.

A great question to ask right now is: "why"! The primary driver is to get ncclient like functionality without needing paramiko for the transport so that we can take full advantage of "normal" OpenSSH options, as well as have fewer dependencies (only absolte required dependency is lxml!). Additionally, as scrapli_netconf is just an extension of scrapli, this means that automation of devices over telnet, SSH, and netconf (over SSH) can be done all with an extremely consistent look and feel. Realistically this should cover most modes of present day network automation other than HTTP based APIs (which would likely have a pretty different look and feel anyway). Finally , but still quite important -- with the asyncssh transport plugin, scrapli_netconf provides asyncio support for netconf operations.

Supported Platforms

At this time scrapli_netconf is a base implementation of netconf 1.0 and netconf 1.1 (note that scrapli is not 100 % RFC compliant in that it currently does not support all methods/options). It should work on anything that runs those versions of netconf, but has only been tested against the following platforms/versions:

• Cisco IOS-XE (tested on: 16.12.03) with Netconf 1.0 and 1.1
• Cisco IOS-XR (tested on: 6.5.3) with Netconf 1.1
• Juniper JunOS (tested on: 17.3R2.10) with Netconf 1.0

Advanced Installation

As outlined in the quick start, you should be able to pip install scrapli_netconf "normally":

pip install scrapli-netconf

To install from this repositories master branch:

pip install git+https://github.com/scrapli/scrapli_netconf

To install from this repositories develop branch:

pip install -e git+https://github.com/scrapli/scrapli_netconf.git@develop#egg=scrapli_netconf

To install from source:

git clone https://github.com/scrapli/scrapli_netconf
cd scrapli_netconf
python setup.py install

scrapli_netconf has made an effort to have as few dependencies as possible -- at this time only requiring scrapli (of course) and lxml. That is a bit of a lie, as right now scrapli_asyncssh (and of course asyncssh) are also required -- in future releases this will likely change to allow you to use scrapli_netconf with only scrapli and lxml installed.

As for platforms to run scrapli_netconf on -- it has and will be tested on MacOS and Ubuntu regularly and should work on any POSIX system. At this time scrapli_netconf will not run on Windows as it requires the system transport or asyncssh transport flavors of scrapli which are not supported on Windows. If you are on Windows and wish to try out scrapli_netconf you can fire up WSL, or this likely works in Cygwin as well.

Basic Usage

Picking the right Driver

Because netconf is a standard we don't need to deal with "platform" type drivers for scrapli_netconf! Instead there are only two options -- NetconfScrape or AsyncNetconfScrape, these can be imported from scrapli_netconf.driver like so:

from scrapli_netconf.driver import NetconfScrape
from scrapli_netconf.driver import AsyncNetconfScrape

Note: if you are using async you must set the transport to asyncssh -- this is the only async transport supported at this time!

Basic Driver Arguments

The drivers of course need some information about the device you are trying to connect to. The most common arguments to provide to the driver are outlined below:

Argument	Purpose/Value
host	name/ip of host to connect to
port	port of host to connect to (defaults to port 830)
auth_username	username for authentication
auth_password	password for authentication
auth_secondary	password for secondary authentication (enable password)
auth_private_key	private key for authentication
auth_strict_key	strict key checking -- TRUE by default!
ssh_config_file	True/False or path to ssh config file to use
strip_namespaces	True/False strip namespaces from returned XML (default False)

These arguments may be passed as keyword arguments to the driver of your choice, or, commonly are passed via dictionary unpacking as show below:

from scrapli_netconf.driver import NetconfScrape

my_device = {
    "host": "172.18.0.11",
    "auth_username": "vrnetlab",
    "auth_password": "VR-netlab9",
    "auth_strict_key": False,
}

conn = NetconfScrape(**my_device)
conn.open()

NOTE that scrapli enables strict host key checking by default!

Opening and Closing a Connection

scrapli_netconf does not open the connection for you when creating your scrapli connection object in normal operations , you must manually call the open method prior to sending any commands to the device as shown below.

from scrapli_netconf.driver import NetconfScrape

my_device = {
   "host": "172.18.0.11",
   "auth_username": "vrnetlab",
   "auth_password": "VR-netlab9",
   "auth_strict_key": False,
}

conn = NetconfScrape(**my_device)
conn.open()
response = conn.get_config(source="running")

Connections can be closed by calling the close method:

conn.close()

Get Config

Configurations can be retrieved from datastores on a netconf device using the get-config netconf method. The get_config method accepts a source argument which must refer to an available datastore on the device -- options for this would be one of:

• running
• startup
• candidate

from scrapli_netconf.driver import NetconfScrape

my_device = {
    "host": "172.18.0.13",
    "auth_username": "vrnetlab",
    "auth_password": "VR-netlab9",
    "auth_strict_key": False,
    "port": 830
}

conn = NetconfScrape(**my_device)
conn.open()
response = conn.get_config(source="running")
print(response.result)

Get

Much like get-config, the get method can be used to get data from the device, generally "operational" or "show " type data. The get method requires a "filter" to be applied in order to identify the data to get -- this filter can be one of two types -- "subtree" (default) or "xpath". In the context of network devices it seems that not many devices support "xpath" filters (only IOSXE with netconf 1.1 of the tested platforms supports xpath for example).

from scrapli_netconf.driver import NetconfScrape

my_device = {
    "host": "172.18.0.13",
    "auth_username": "vrnetlab",
    "auth_password": "VR-netlab9",
    "auth_strict_key": False,
    "port": 830
}

filter_ = """
<components xmlns="http://openconfig.net/yang/platform">
    <component>
        <state>
        </state>
    </component>
</components>"""

conn = NetconfScrape(**my_device)
conn.open()
response = conn.get(filter_=filter_, filter_type="subtree")
print(response.result)

Lock and Unlock

Netconf provides the ability to lock a configuration datastore. Much like get-config a target datastore must be provided, and is dependant on the capabilities of the platform you are interacting with.

from scrapli_netconf.driver import NetconfScrape

my_device = {
    "host": "172.18.0.13",
    "auth_username": "vrnetlab",
    "auth_password": "VR-netlab9",
    "auth_strict_key": False,
    "port": 830
}

conn = NetconfScrape(**my_device)
conn.open()
response = conn.lock(target="candidate")
print(response.result)
response = conn.unlock(target="candidate")
print(response.result)

Commit and Discard

If your platform supports commit operations (IOS-XR and Junos in the context of scrapli_netconf tested platforms ), any changes created using the edit-config method will need to be commited (or discarded).

from scrapli_netconf.driver import NetconfScrape

my_device = {
    "host": "172.18.0.13",
    "auth_username": "vrnetlab",
    "auth_password": "VR-netlab9",
    "auth_strict_key": False,
    "port": 830
}

conn = NetconfScrape(**my_device)
conn.open()
response = conn.commit()
print(response.result)
response = conn.discard()
print(response.result)

Edit Config

To edit configs, simply use the edit_config method with an appropriate config payload and target.

from scrapli_netconf.driver import NetconfScrape

my_device = {
    "host": "172.18.0.13",
    "auth_username": "vrnetlab",
    "auth_password": "VR-netlab9",
    "auth_strict_key": False,
    "port": 830
}

cdp_config = """
<config>
    <cdp xmlns="http://cisco.com/ns/yang/Cisco-IOS-XR-cdp-cfg">
        <timer>80</timer>
        <enable>true</enable>
        <log-adjacency></log-adjacency>
        <hold-time>200</hold-time>
        <advertise-v1-only></advertise-v1-only>
    </cdp>
</config>
"""

conn = NetconfScrape(**my_device)
conn.open()
result = conn.edit_config(config=cdp_config, target="candidate")
print(result.result)

Delete Config

Some devices may allow you to delete a candidate/startup configuration. You can do so with the delete_config method ; note that this is only currently tested on Junos as the test environment IOSXR version does not support this method . Per the RFC, "running" is never a valid target; scrapli_netconf will produce a warning indicating this if "running" is set as the target; if strict_datastores is set to True an exception will be raised.

from scrapli_netconf.driver import NetconfScrape

my_device = {
    "host": "172.18.0.13",
    "auth_username": "vrnetlab",
    "auth_password": "VR-netlab9",
    "auth_strict_key": False,
    "port": 830
}

conn = NetconfScrape(**my_device)
conn.open()
result = conn.delete_config(target="candidate")
print(result.result)

RPC

The rpc method is a "bare-bones" rpc call which does not apply any formatting/standardization beyond the outer most rpc tag. Generally this is used for Juniper devices and the "bare rpc" type calls supported on junos devices not supporting/using models (YANG/IETF/etc.), but can of course be used to send any kind of custom crafted rpc you'd like!

from scrapli_netconf.driver import NetconfScrape

my_device = {
    "host": "172.18.0.15",
    "auth_username": "vrnetlab",
    "auth_password": "VR-netlab9",
    "auth_strict_key": False,
    "port": 22
}

commit_filter = """
<get-commit-revision-information>
    <level>detail</level>
</get-commit-revision-information>
"""

conn = NetconfScrape(**my_device)
conn.open()
result = conn.rpc(filter_=commit_filter)
print(result.result)

Advanced Usage

Capabilities

Netconf capabilities are exchanged when the session is opened. scrapli_netconf stores the server's capabilities in the aptly named server_capabilities attribute of the driver.

>>> from scrapli_netconf.driver import NetconfScrape
>>> 
>>> my_device = {
...     "host": "172.18.0.13",
...     "auth_username": "vrnetlab",
...     "auth_password": "VR-netlab9",
...     "auth_strict_key": False,
...     "port": 830
... }
>>> conn = NetconfScrape(**my_device)
>>> conn.open()
>>> conn.server_capabilities
['urn:ietf:params:netconf:base:1.1', 'urn:ietf:params:netconf:capability:candidate:1.0']

Capabilities truncated for readability

As for capabilities that scrapli_netconf sends to the server, that depends on the capabilities advertised from the server! If netconf base 1.1 is in the advertised capabilities then scrapli_netconf will advertise netconf 1.1 capabilities, otherwise it will advertise 1.0 capabilities.

Datastores

scrapli_netconf drives contain an option strict_datastores which defaults to False. If this option is set to True scrapli will raise a ValueError when attempting to perform an operation against a datastore that has not been advertised as a capability by the server. With this option left to the default value of False , scrapli_netconf will simply issue a user warning.

FAQ

• Question: Why build this? ncclient exists?
  • Answer: After building scrapli it was apparent that it could be fairly easily extended to handle netconf connections, at the time dayjob$ had lots of netconf-y things with ncclient happening. I'm not a big fan of ncclient as I find it rather obtuse/hard to understand whats going on, and the dependency on paramiko is not super great. I figured I could support enough netconf things with system transport so... I did. Then it was fairly trivial to add asyncssh to support netconf with asyncio!
• Question: Is this better than ncclient?
  • Answer: Nope! Supporting asyncio may be a killer use case for some, but otherwise ncclient and scrapli_netconf accomplish much of the same things -- probably with ncclient having a wider/deeper range of netconf rfc support . Net/net though is they are just different! Use whichever you prefer!
• Question: Is this easy to use?
  • Answer: Biased, but I think so! A big part of the goal of all of this was to have a consistent feel across ssh and netconf both with sync and async support, and (again, biased) I think that has been achieved.
• Other questions? Ask away!

Linting and Testing

Please see scrapli Linting and Testing for details.