scrapli 2020.2.14

Screen scraping (ssh|telnet) client focused on network devices

scrapli

scrapli -- scrap(e c)li -- is a python library focused on connecting to devices, specifically network devices (routers/switches/firewalls/etc.) via SSH or Telnet. The name scrapli -- is just "scrape cli" (as in screen scrape) squished together! scrapli's goal is to be as fast and flexible as possible, while providing a well typed, well documented, simple API.

scrapli is built primarily in three parts: transport, channel, and driver. The transport layer is responsible for providing a file-like interface to the target SSH server. The channel layer is responsible for reading and writing to the provided file-like interface. Finally, the driver provides the user facing API/interface to scrapli.

There are four available "transports" for the transport layer -- all of which inherit from a base transport class and provide the same file-like interface to the upstream channel. The transport options are:

• paramiko
• ssh2-python
• OpenSSH/System available SSH
• telnetlib

A good question to ask at this point is probably "why?". Why multiple transport options? Why not just use paramiko like most folks do? Historically the reason for moving away from paramiko was simply speed. ssh2-python is a wrapper around the libssh2 C library, and as such is very very fast. In a prior project (ssh2net), of which scrapli is the successor/evolution, ssh2-python was used with great success, however, it is a bit feature-limited, and development seems to have stalled.

This led to moving back to paramiko, which of course is a fantastic project with tons and tons of feature support . Paramiko, however, does not provide "direct" OpenSSH support (as in -- auto-magically like when you ssh on your normal shell), and I don't believe it provides 100% full OpenSSH support either (ex: ControlPersist). Fully supporting an OpenSSH config file would be an ideal end goal for scrapli, something that may not be possible with Paramiko - ControlPersist in particular is very interesting to me.

With the goal of supporting all of the OpenSSH configuration options the final transport driver option is simply native system local SSH (almost certainly this won't work on Windows, but I don't have a Windows box to test on, or any particular interest in doing so). The implementation of using system SSH is of course a little bit messy , however scrapli takes care of that for you so you don't need to care about it! The payoff of using system SSH is of course that OpenSSH config files simply "work" -- no passing it to scrapli, no selective support, no need to set username or ports or any of the other config items that may reside in your SSH config file. This driver will likely be the focus of most development for this project, though I will try to keep the other transport drivers -- in particular ssh2-python -- as close to parity as is possible/practical.

The final piece of scrapli is the actual "driver" -- or the component that binds the transport and channel together and deals with instantiation of an scrapli object. There is a "base" driver object -- Scrape -- which provides essentially a "raw" SSH connection with read and write methods (provided by the channel object), and not much else. More specific "drivers" can inherit from this class to extend functionality of the driver to make it more friendly for network devices. In fact, there is a NetworkDriver which does just that. This NetworkDriver isn't really meant to be used directly though, but to be further extended and built upon instead. As this library is focused on interacting with network devices, an example scrapli driver (built on the NetworkDriver) would be the IOSXE driver -- to, as you may have guessed, interact with devices running Cisco's IOS-XE operating system.

Table of Contents

• Documentation
• Supported Platforms
• Installation
• Examples Links
• Basic Usage
  • Native and Platform Drivers Examples
  • Platform Regex
  • Basic Operations -- Sending and Receiving
  • Response Objects
  • Handling Prompts
  • Driver Privilege Levels
  • Sending Configurations
  • TextFSM/NTC-Templates Integration
  • Timeouts
  • Disabling Paging
  • Login Handlers
  • SSH Config Support
  • Telnet
• FAQ
• Transport Notes
• Known Issues
• Linting and Testing
• Todo and Roadmap

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 the readme as a web page here.

To regenerate documentation locally, use the following make command:

make docs

Supported Platforms

scrapli "core" drivers cover basically the NAPALM platforms -- Cisco IOS-XE, IOS-XR, NX-OS, Arista EOS, and Juniper JunOS. These drivers provide an interface tailored to network device "screen-scraping" rather than just a generic SSH connection/channel. Below are the core driver platforms and currently tested version.

• Cisco IOS-XE (tested on: 16.04.01)
• Cisco NX-OS (tested on: 9.2.4)
• Juniper JunOS (tested on: 17.3R2.10)
• Cisco IOS-XR (tested on: 6.5.3)
• Arista EOS (tested on: 4.22.1F)

In the future it would be possible for folks to contribute additional "community" drivers, however, is unlikely that any additional "core" platforms would be added.

The "driver" pattern is pretty much exactly like the implementation in NAPALM. The driver extends the base class (Scrape)/base networking driver class (NetworkDriver) with device specific functionality such as privilege escalation/de-escalation, setting appropriate prompts to search for, and picking out appropriate ntc templates for use with TextFSM.

All of this is focused on network device type SSH cli interfaces, but should work on pretty much any SSH connection (though there are almost certainly better options for non-network type devices!). The "base" (Scrape) connection does not handle any kind of device-specific operations such as privilege escalation or saving configurations, it is simply intended to be a bare bones connection that can interact with nearly any device/platform if you are willing to send/parse inputs/outputs manually.

The goal for all "core" devices will be to include functional tests that can run against vrnetlab containers to ensure that the "core" devices are as thoroughly tested as is practical.

Installation

You should be able to pip install it "normally":

pip install scrapli

To install from this repositories master branch:

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

To install from source:

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

scrapli has made an effort to have as few dependencies as possible -- in fact to have ZERO dependencies! The "core" of scrapli can run with nothing other than standard library! If you wish to use paramiko or ssh2-python as a driver , however, you of course need to install those. This can be done with pip:

pip install scrapli[paramiko]

The available optional installation options are:

• paramiko
• ssh2 (ssh2-python)
• textfsm (textfsm and ntc-templates)

As for platforms to run scrapli on -- it has and will be tested on MacOS and Ubuntu regularly and should work on any POSIX system.

Examples Links

• Basic "native" Scrape operations
• Basic "driver" Scrape operations
• Setting up basic logging
• Using SSH Key for authentication
• Using SSH config file

Basic Usage

Native and Platform Drivers Examples

Example Scrape "native/base" connection:

from scrapli import Scrape

my_device = {"host": "172.18.0.11", "auth_username": "vrnetlab", "auth_password": "VR-netlab9", "auth_strict_key": False}
conn = Scrape(**my_device)
conn.open()
# do stuff!

Example IOS-XE driver setup. This also shows using context manager which is also supported on "native" mode -- when using the context manager there is no need to call the "open_shell" method:

from scrapli.driver.core import IOSXEDriver

my_device = {"host": "172.18.0.11", "auth_username": "vrnetlab", "auth_password": "VR-netlab9", "auth_strict_key": False}
with IOSXEDriver(**my_device) as conn:
    print(conn)
    # do stuff!

Platform Regex

Due to the nature of SSH there is no good way to know when a command has completed execution. Put another way, when sending any command, data is returned over a socket, that socket doesn't ever tell us when it is "done" sending the output from the command that was executed. In order to know when the session is "back at the base prompt/starting point" scrapli uses a regular expression pattern to find that base prompt.

This pattern is contained in the comms_prompt_pattern setting, and is perhaps the most important argument to getting scrapli working.

The "base" (default, but changeable) pattern is:

"^[a-z0-9.\-@()/:]{1,20}[#>$]$"

NOTE all comms_prompt_pattern should use the start and end of line anchors as all regex searches in scrapli are multline (this is an important piece to making this all work!). While you don't need to use the line anchors its probably a really good idea!

The above pattern works on all "core" platforms listed above for at the very least basic usage. Custom prompts or hostnames could in theory break this, so be careful!

If you do not wish to match Cisco "config" level prompts you could use a comms_prompt_pattern such as:

"^[a-z0-9.-@]{1,20}[#>$]$"

If you use a platform driver, the base prompt is set in the driver so you don't really need to worry about this!

The comms_prompt_pattern pattern can be changed at any time at or after instantiation of an scrapli object. Changing this can break things though, so be careful!

Basic Operations -- Sending and Receiving

Sending inputs and receiving outputs is done through the base Scrape object or your selected driver object. The inputs /outputs all are processed (sent/read) via the channel object. If using the base Scrape object you must use the channel.send_inputs method -- the NetworkDriver and platform specific drivers have a send_commands method as outlined below (second example). The following example shows sending a "show version" command as a string. Also shown: send_inputs accepts a list/tuple of commands. Finally -- note that Scrape does NOT disable paging , so in this example we need to do that (show version and show run both will need paging disabled!).

from scrapli import Scrape

my_device = {"host": "172.18.0.11", "auth_username": "vrnetlab", "auth_password": "VR-netlab9", "auth_strict_key": False}
with Scrape(**my_device) as conn:
    results = conn.channel.send_inputs("terminal length 0")
    results = conn.channel.send_inputs("show version")
    results = conn.channel.send_inputs(("show version", "show run"))

When using a network "driver", it is more desirable to use the send_commands method to send commands (commands that would be ran at privilege exec in Cisco terms, or similar privilege level for the other platforms). send_commands is just a thin wrapper around send_inputs, however it ensures that the device is at the appropriate prompt (default_desired_priv attribute of the specific driver, see Driver Privilege Levels).

from scrapli.driver.core import IOSXEDriver

my_device = {"host": "172.18.0.11", "auth_username": "vrnetlab", "auth_password": "VR-netlab9", "auth_strict_key": False}
with IOSXEDriver(**my_device) as conn:
    results = conn.send_commands("show version")
    results = conn.send_commands(("show version", "show run"))

Response Objects

All read operations result in a Response object being created. The Response object contains attributes for the command sent (channel_input), start/end/elapsed time, and of course the result of the command sent.

from scrapli.driver.core import IOSXEDriver

my_device = {"host": "172.18.0.11", "auth_username": "vrnetlab", "auth_password": "VR-netlab9", "auth_strict_key": False}
with IOSXEDriver(**my_device) as conn:
    results = conn.send_commands("show version")
    print(results[0].elapsed_time)
    print(results[0].result)

scrapli always returns a list of Response objects, even if the amount of responses is just one. In addition to containing the input and output of the command(s) that you sent, the Response object also contains a method textfsm_parse_output which will attempt to parse the received output and assign it to the structured_result attribute of the Response object. If parsing fails, the value assigned to the structured_result attribute will be an empty list.

>>> results[0].textfsm_parse_output()
>>> print(results[0].structured_result)
[['16.4.1', 'IOS-XE', 'csr1000v', '2 days, 22 hours, 10 minutes', 'reload', 'packages.conf', ['CSR1000V'], ['9FKLJWM5EB0'], '0x2102', []]]

Handling Prompts

In some cases you may need to run an "interactive" command on your device. The channel.send_inputs_interact method can be used to handle these situations if using the base Scrape driver -- if using the NetworkBase or any of the platform drivers, the send_interactive method can be used to accomplish this -- send_interactive is just a thin wrapper around the channel.send_inputs_interact method for convenience (not having to call a channel method basically). This method accepts a tuple containing the initial input (command) to send, the expected prompt after the initial send, the response to that prompt, and the final expected prompt -- basically telling scrapli when it is done with the interactive command. In the second example below (using the IOSXEDriver) the expectation is that the current /base prompt is the final expected prompt, so we can simply call the get_prompt method to snag that directly off the router.

from scrapli import Scrape

my_device = {"host": "172.18.0.11", "auth_username": "vrnetlab", "auth_password": "VR-netlab9", "auth_strict_key": False}
interact = ["clear logging", "Clear logging buffer [confirm]", "\n"]

with Scrape(**my_device) as conn:
    interactive = conn.channel.send_inputs_interact(
                ("clear logging", "Clear logging buffer [confirm]", "\n", "csr1000v#")
            )

Or with the NetworkDriver or any platform driver:

from scrapli.driver.core import IOSXEDriver

my_device = {"host": "172.18.0.11", "auth_username": "vrnetlab", "auth_password": "VR-netlab9", "auth_strict_key": False}
interact = ["clear logging", "Clear logging buffer [confirm]", "\n"]

with IOSXEDriver(**my_device) as conn:
    interactive = conn.send_interactive(
                ("clear logging", "Clear logging buffer [confirm]", "\n", conn.get_prompt())
            )

Driver Privilege Levels

The "core" drivers understand the basic privilege levels of their respective device types. As mentioned previously , the drivers will automatically attain the "privilege_exec" (or equivalent) privilege level prior to executing "show " commands. If you don't want this "auto-magic" you can use the base driver (Scrape). The privileges for each device are outlined in named tuples in the platforms driver.py file.

As an example, the following privilege levels are supported by the IOSXEDriver:

1. "exec"
2. "privilege_exec"
3. "configuration"
4. "special_configuration"

Each privilege level has the following attributes:

• pattern: regex pattern to associate prompt to privilege level with
• name: name of the priv level, i.e. "exec"
• deescalate_priv: name of next lower privilege or None
• deescalate: command to deescalate to next lower privilege or None
• escalate: name of next higher privilege or None
• escalate_auth: command to escalate to next higher privilege or None
• escalate_prompt: False or pattern to expect for escalation -- i.e. "Password:"
• requestable: True/False if the privilege level is requestable
• level: integer value of level i.e. 1

If you wish to manually enter a privilege level you can use the acquire_priv method, passing in the name of the privilege level you would like to enter. In general you probably won't need this too often though as the driver should handle much of this for you.

from scrapli.driver.core import IOSXEDriver

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

with IOSXEDriver(**my_device) as conn:
    conn.acquire_priv("configuration")

Sending Configurations

When using the native mode (Scrape object), sending configurations is no different than sending commands and is done via the send_inputs method. You must manually ensure you are in the correct privilege/mode.

When using any of the core drivers, you can send configurations via the send_configs method which will handle privilege escalation for you. As with the send_commands and send_inputs methods -- you can send a single string or a list/tuple of strings.

from scrapli.driver.core import IOSXEDriver

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

with IOSXEDriver(**my_device) as conn:
    conn.send_configs(("interface loopback123", "description configured by scrapli"))

TextFSM/NTC-Templates Integration

scrapli supports parsing output with TextFSM. This of course requires installing TextFSM and having ntc-templates somewhere on your system. When using a platform driver (i.e. IOSXEDriver) the textfsm-platform will be set for you . If you wish to parse the output of your send commands, you can use the textfsm_parse_output method of the response object. This method will attempt to find the template for you -- based on the textfsm-platform and the channel-input. If textfsm parsing succeeds, the structured result is assigned to the structed_result attribute of the response object. If textfsm parsing fails, an empty list is assigned to the structured_result attribute.

from scrapli.driver.core import IOSXEDriver

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

with IOSXEDriver(**my_device) as conn:
    results = conn.send_commands("show version")
    results[0].textfsm_parse_output()
    print(results[0].structured_result)

scrapli also supports passing in templates manually (meaning not using the pip installed ntc-templates directory to find templates) if desired. The scrapli.helper.textfsm_parse function accepts a string or loaded (TextIOWrapper ) template and output to parse. This can be useful if you have custom or one off templates or don't want to pip install ntc-templates.

from scrapli.driver.core import IOSXEDriver
from scrapli.helper import textfsm_parse

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

with IOSXEDriver(**my_device) as conn:
    results = conn.send_commands("show version")
    structured_result = textfsm_parse("/path/to/my/template", results[0].result)

NOTE: If a template does not return structured data an empty string will be returned!

Timeouts

scrapli supports several timeout options. The simplest is the timeout_socket which controls the timeout for... setting up the underlying socket in seconds. Value should be a positive, non-zero number, however ssh2 and paramiko transport options support floats. timeout_scoket is not used when using the telnet transport option.

timeout_transport sets the timeout for the actual transport session setup (system|paramiko|ssh2|telnet) -- for example for system transport this is the SSH ConnectTimeout value.

Finally, timeout_ops sets a timeout value for individual operations -- or put another way, the timeout for each send_input operation.

Disabling Paging

scrapli Scrape driver attempts to send terminal length 0 to disable paging by default. In the future this will likely be removed and relegated to the device drivers only. For all drivers, there is a standard disable paging string already configured for you, however this is of course user configurable. In addition to passing a string to send to disable paging, scrapli supports passing a callable. This callable should accept the drivers reference to self as the only argument. This allows for users to create a custom function to disable paging however they like . This callable option is supported on the native driver as well. In general it is probably a better idea to handle this by simply passing a string, but the goal is to be flexible so the callable is supported.

from scrapli.driver.core import IOSXEDriver

def iosxe_disable_paging(cls):
    cls.send_commands("term length 0")

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

with IOSXEDriver(**my_device) as conn:
    print(conn.get_prompt())

Login Handlers

Some devices have additional prompts or banners at login. This generally causes issues for SSH screen scraping automation. scrapli supports -- just like disable paging -- passing a string to send or a callable to execute after successful SSH connection but before disabling paging occurs. By default this is an empty string which does nothing.

SSH Config Support

scrapli supports using OpenSSH configuration files in a few ways. For "system" SSH transport, passing a path to a config file will simply make scrapli "point" to that file, and therefore use that configuration files attributes (because it is just exec'ing system SSH!). See the Transport Notes section for details about what Transport supports what configuration options.

NOTE -- when using the system (default) SSH transport driver scrapli does NOT disable strict host checking by default . Obviously this is the "smart" behavior, but it can be overridden on a per host basis in your SSH config file, or by passing False to the "auth_strict_key" argument on object instantiation.

from scrapli.driver.core import IOSXEDriver

my_device = {"host": "172.18.0.11", "ssh_config_file": "~/mysshconfig", "auth_strict_key": False, "auth_password": "VR-netlab9"}

with IOSXEDriver(**my_device) as conn:
    print(conn.get_prompt())

Telnet

scrapli supports telnet as a transport driver via the standard library module telnetlib. Telnet is a bit of a special case for scrapli, here are the things you need to know if you wish to use Telnet:

• Currently, you must set the port number. At the moment scrapli assumes SSH and defaults to port 22, even if you specify the telnet driver. This could obviously change in the future but for now, specify your telnet port!
• You can set the username and password prompt expect string after Scrape (or network driver) object instantiation and before calling the open method -- this means if you have non-default prompts you cannot use scrapli with a context manager and Telnet (because the context manager calls open for you). You can set the prompts using the following attributes of the Scrape object:
  • username_prompt
  • password_prompt

If telnet for some reason becomes an important use case, the telnet Transport layer can be improved/augmented.

FAQ

• Question: Why build this? Netmiko exists, Paramiko exists, Ansible exists, etc...?
  • Answer: I built ssh2net to learn -- to have a goal/target for writing some code. scrapli is an evolution of the lessons learned building ssh2net. About mid-way through building ssh2net I realized it may actually be kinda good at doing... stuff. So, sure there are other tools out there, but I think scrapli its pretty snazzy and fills in some of the gaps in other tools. For example scrapli is 100% compliant with strict mypy type checking, very uniformly documented/linted, contains a results object for every operation, is very very fast, is very flexible, and in general pretty awesome! Finally, while I think in general that SSH "screen scraping" is not "sexy" or even "good", it is the lowest common denominator for automation in the networking world. So I figured I could try to make the fastest, most flexible library around for SSH network automation!
• Question: Is this better than Netmiko/Paramiko/Ansible?
  • Answer: Nope! It is different though! The main focus is just to be stupid fast. It is very much that. It should be super reliable too as the timeouts are very easy/obvious to control, and it should also be very very very easy to adapt to any other network-y type CLI.
• Question: Is this easy to use?
  • Answer: Yep! The "native" usage is pretty straight forward -- the thing to remember is that it doesn't do "things " for you like Netmiko does for example, so its a lot more like Paramiko in that regard. That said you can use one of the available drivers to have a more Netmiko-like experience -OR- write your own driver as this has been built with the thought of being easily extended.
• Why do I get a "conn (or your object name here) has no attribute channel" exception when using the base Scrape or NetworkDriver objects?
  • Answer: Those objects do not "auto open", and the channel attribute is not assigned until opening the connection . Call conn.open() (or your object name in place of conn) to open the session and assign the channel attribute.
• Other questions? Ask away!

Transport Notes

paramiko

• I'll think of something...

SSH Config Supported Arguments

• N/A at the moment

ssh2-python

• See caveats section for a few items...

SSH Config Supported Arguments

• user
• port
• identity_file

system

• Any arguments passed to the SystemSSHTransport class will override arguments in your ssh config file. This is because the arguments get crafted into an "open_cmd" (the command that actually fires off the ssh session), and these cli arguments take precedence over the config file arguments.
• strict key checking is ENABLED by default! If you see weird EOF errors immediately after opening a connection, you probably did not disable strict key checking!

SSH Config Supported Arguments

• literally whatever your system supports as scrapli just execs SSH on your system!

telnet

• See the telnet section!

SSH Config Supported Arguments

• Obviously none!

Known Issues

SSH2-Python

• Arista EOS uses keyboard interactive authentication which is currently broken in the pip-installable version of ssh2-python (as of January 2020). GitHub user Red-M has contributed to and fixed this particular issue but the fix has not been merged. If you would like to use ssh2-python with EOS I suggest cloning and installing via Red-M's repository or my fork of Red-M's fork!

• Use the context manager where possible! More testing needs to be done to confirm/troubleshoot, but limited testing seems to indicate that without properly closing the connection there appears to be a bug that causes Python to crash on MacOS at least. More to come on this as I have time to poke it more! I believe this is only occurring on the latest branch/update (i.e. not on the pip installable version).

Linting and Testing

NOTE Currently there are no unit/functional tests for IOSXR/NXOS/EOS/Junos, however as this part of scrapli is largely a port of ssh2net, they should work :)

Linting

This project uses black for auto-formatting. In addition to black, tox will execute pylama, and pydocstyle for linting purposes . Tox will also run mypy, with strict type checking. Docstring linting with darglint which has been quite handy!

All commits to this repository will trigger a GitHub action which runs tox, but of course its nicer to just run that before making a commit to ensure that it will pass all tests!

Typing

As stated, this project is 100% type checked and will remain that way. The value this adds for IDE auto-completion and just general sanity checking/forcing writing of more type-check-able code is worth the small overhead in effort.

Testing

I broke testing into two main categories -- unit and functional. Unit is what you would expect -- unit testing the code. Functional testing connects to virtual devices in order to more accurately test the code. Unit tests cover quite a bit of the code base due to mocking the FileIO that the channel reads/writes to. This gives a pretty high level of confidence that at least object instantiation and channel read/writes will generally work... Functional tests against virtual devices helps reinforce that and gets coverage for the transport classes.

Unit Tests

Unit tests can be executed via pytest:

python -m pytest tests/unit/

Or using the following make command:

make test_unit

If you would like to see the coverage report and generate the html coverage report:

make cov_unit

Setting up Functional Test Environment

Executing the functional tests is a bit more complicated! First, thank you to Kristian Larsson for his great tool vrnetlab! All functional tests are built on this awesome platform that allows for easy creation of containerized network devices.

Basic functional tests exist for all "core" platform types (IOSXE, NXOS, IOSXR, EOS, Junos). Vrnetlab currently only supports the older emulation style NX-OS devices, and not the newer VM image n9kv. I have made some very minor tweaks to vrnetlab locally in order to get the n9kv image running -- I have raised a PR to add this to vrnetlab proper. Minus the n9kv tweaks, getting going with vrnetlab is fairly straightforward -- simply follow Kristian's great readme docs. For the Arista EOS image -- prior to creating the container you should boot the device and enter the zerotouch disable command. This allows for the config to actually be saved and prevents the interfaces from cycling through interface types in the container (I'm not clear why it does that but executing this command before building the container "fixes" this!).

The docker-compose file here will be looking for the container images matching this pattern, so this is an important bit! The container image names should be:

scrapli-cisco-iosxe
scrapli-cisco-nxos
scrapli-cisco-iosxr
scrapli-arista-eos
scrapli-juniper-junos

You can tag the image names on creation (following the vrnetlab readme docs), or create a new tag once the image is built:

docker tag [TAG OF IMAGE CREATED] scrapli-[VENDOR]-[OS]

NOTE I have added vty lines 5-98 on the CSR image -- I think the connections opening/closing so quickly during testing caused them to get hung. Testing things more slowly (adding time.sleep after closing connections) fixed this but that obviously made the testing time longer, so this seemed like a better fix. This change will be in my fork of vrnetlab or you can simply modify the line vty 0 5 --> line vty 0 98 in the luanch.py for the CSR in your vrnetlab clone. line vty 1 for some reason also had length 0 which I have removed (and tests expect to be gone). Lastly, to test telnet the csr setup in vrnetlab needs to be modified to allow telnet as well; this means the Dockerfile must expose port 23, the qemu nic settings must support port 23 being sent into the VM and socat must also be setup appropriately. This should all be updated in my vrnetlab fork.

Functional Tests

Once you have created the images, you can start the containers with a make command:

make start_dev_env

Conversely you can terminate the containers:

make stop_dev_env

To start a specific platform container:

make start_dev_env_iosxe

Substitute "iosxe" for the platform type you want to start.

Most of the containers don't take too long to fire up, maybe a few minutes (running on my old macmini with Ubuntu, so not exactly a powerhouse!). That said, the IOS-XR device takes about 15 minutes to go to "healthy" status. Once booted up you can connect to their console or via SSH:

Device	Local IP
iosxe	172.18.0.11
nxos	172.18.0.12
iosxr	172.18.0.13
eos	172.18.0.14
junos	172.18.0.15

The console port for all devices is 5000, so to connect to the console of the iosxe device you can simply telnet to that port locally:

telnet 172.18.0.11 5000

Credentials for all devices use the default vrnetlab credentials:

Username: vrnetlab

Password: VR-netlab9

Once the container(s) are ready, you can use the make commands to execute tests as needed:

• test will execute all currently implemented functional tests as well as the unit tests
• test_functional will execute all currently implemented functional tests
• test_iosxe will execute all unit tests and iosxe functional tests
• test_nxos will execute all unit tests and nxos functional tests
• test_iosxr will execute all unit tests and iosxr functional tests
• test_eos will execute all unit tests and eos functional tests
• test_junos will execute all unit tests and junos functional tests

Todo and Roadmap

This section may not get updated much, but will hopefully reflect the priority items for short term (todo) and longer term (roadmap) for scrapli.

Todo

• Paramiko Transport ssh config support -- at least for user/port/identity-file (to match ssh2-python current support)
• Continue to bring in features from ssh2net -- at the moment finishing/adding ssh config support is the priority , however it would be good to add keep alives and some other widgets from ssh2net in a more optimized, cleaned up fashion here in scrapli.
• Investigate blocking modes and timeouts further. This was reasonably fleshed out in ssh2net I think, but less so here... it seems to not actually be needed (the ability to flip between blocking and non-blocking reads), so it may be worth removing this from the base Transport class entirely to simplify things.
• Investigate pre-authentication handling for telnet -- support handling a prompt before auth happens i.e. accept some banner/message -- does this ever happen for ssh? I don't know! If so, support dealing with that as well.
• Remove as much as possible from the vendor'd ptyprocess code. Type hint it, add docstrings everywhere, add tests if possible (and remove from ignore for test coverage and darglint).
• Improve testing in general... make it more orderly/nicer, retry connections automatically if there is a failure (failures happen from vtys getting tied up and stuff like that it seems), shoot for even better coverage!
• Remove disable paging "stuff" from the base Scrape class -- thats really network specific and doesnt belog in a base ssh type class.
• Add a dummy container (like nornir maybe?) to use for functional testing -- its very likely folks won't have a vrnetlab setup or compute to set that up... it'd be nice to have a lightweight container that can be used for basic testing of Scrape and for testing auth with keys and such.

Roadmap

• Async support. This is a bit of a question mark as I personally don't know even where to start to implement this , and have no real current use case... that said I think it would be cool if for no other reason than to learn!
• Plugins -- make the drivers all plugins!
• Nonrir plugin -- make scrapli a Nornir plugin!

Things that may or may not happen

• Modify send_commands to only accept a list/tuple of commands. Add a send_command method which only accepts a single command. The idea would be to be more exacting/make docs more specific/etc. but not sure I'm fully bought into this yet.
• Add a validate_host arg to the base Scrape class (like ssh2net) to validate host is resolvable/socket can be opened before bothering attempting to do so for real (as an option).