Connection Basics

There are two primary ways of creating device CLI connections using Unicon:

  1. using pyATS testbed YAML files

  2. using native Python Unicon APIs

Using pyATS Testbed YAML

The simplest way to create a device connection using Unicon is through a pyATS testbed YAML file.

The testbed YAML file contains all necessary information that instructs Unicon on how a connection should be established (eg, using what parameters and credentials).

  # Example
  # -------
  #
  #   a simple pyATS testbed YAML file


devices:
    csr1000v-1:
        type: router
        os: iosxe
        credentials:
            default:
                password: cisco123
                username: admin
            enable:
                password: cisco123
        connections:
            cli:
                protocol: ssh
                ip: 168.10.1.35

Note that in the above file, the following key values are used by Unicon to identify the proper plugin to use to create the underlying connection:

  • os: - OS details of the device [required]

  • series: - platform series of the the device [optional]

  • model: - platform model of the device [optional]

If an equivalent unicon connection plugin is not found for a device, unicon will use the generic plugin.

Tip

The supported OS and series information can be found here: Supported Platforms.

Now, you can establish connectivity to this device within your test scripts, or within Python:

# Example
# -------
#
#   using the above testbed yaml file in pyATS

from pyats.topology import loader

testbed = loader.load('my-testbed.yaml')

device = testbed.devices['csr1000v-1']

device.connect()

device.execute('show version')

Customizing Your Connection

In order to allow users to tune unicon plugin behavior without the need for any code changes, several kinds of overrides may be made from the testbed YAML itself.

Connecting to a pyATS device via unicon ultimately results in a unicon Connection object being created.

The following parameters are eligible for override under the arguments key in the testbed YAML connection block:

  • learn_hostname

  • prompt_recovery

  • init_exec_commands

  • init_config_commands

  • mit

  • log_stdout

  • debug

  • goto_enable

  • standby_goto_enable

A connection, once created, has a settings parameter whose contents and defaults are plugin-dependent. It is possible to override these settings from the testbed YAML file via the settings key.

Settings can be accessed here.

A connection is assigned a plugin-dependent list of services when it is created. It is possible to override any service attribute from the testbed YAML file via the service_attributes key.

The following testbed YAML shows these three kinds of override:

device1:
    os: 'nxos'
    series: 'n7k'
    type: 'router'
    credentials:
        default:
            username: lab
            password: lab
    connections:
      a:
        protocol: telnet
        ip: 10.64.70.11
        port: 2042

        arguments:
          connection_timeout: 120
          mit: True

        settings:
          ESCAPE_CHAR_CHATTY_TERM_WAIT: 1

        service_attributes:
          ping:
            timeout: 1234

Note

Details specified under the arguments, settings or service_attributes connection block keys take precedence over any identically-named details passed to the device.connect() call.

Using the above testbed YAML as an example:

Calling device1.connect(connection_timeout=240) results in device1.connection_timeout being set to 120.

Calling device1.connect(settings=dict(ESCAPE_CHAR_CHATTY_TERM_WAIT=10)) results in device1.settings.ESCAPE_CHAR_CHATTY_TERM_WAIT being set to 1.

Calling device1.connect(service_attributes=dict(ping=dict(timeout=1))) results in device1.ping.timeout being set to 1234.

If you want to change to default timeout value for execute and configure service, you can set the EXEC_TIMEOUT and CONFIG_TIMEOUT in the testbed file:

device1:
    os: 'nxos'
    series: 'n7k'
    type: 'router'
    credentials:
        default:
            username: lab
            password: lab
    connections:
      a:
        protocol: telnet
        ip: 10.64.70.11
        port: 2042

        settings:
          EXEC_TIMEOUT: 120
          CONFIG_TIMEOUT: 120

Example: Single NXOS

Every other platform can use the same sample file by changing the os, series, model. The Moonshine platform does not require a username or password, so these are omitted (see below for an example).

step-n7k-1:
    os: 'nxos'
    series: 'n7k'
    type: 'router'
    credentials:
        default:
            username: lab
            password: lab
    connections:
      defaults:
        class: 'unicon.Unicon'
      a:
        protocol: telnet
        ip: 10.64.70.11
        port: 2042

For more info on testbed refer to topology package.

Connecting to the device using the above testbed file:

Note

unicon Connection arguments may be passed in the pyATS device.connect(). For example: device.connect(learn_hostname=True).

>>> from pyats.topology import loader
>>> tb = loader.load("testbed.yaml")
>>> uut = tb.devices['step-n7k-1']
>>> uut.connect()

2016-04-06T12:06:50: %UNICON-INFO: +++ initializing context +++

2016-04-06T12:06:50: %UNICON-INFO: +++ initializing state_machine +++

2016-04-06T12:06:50: %UNICON-INFO: +++ initializing services +++

2016-04-06T12:06:50: %UNICON-INFO: adding service  ping   :  <unicon.plugins.generic.service_implementation.Ping object at 0x10441ff98>

2016-04-06T12:06:50: %UNICON-INFO: adding service  reload   :  <unicon.plugins.nxos.service_implementation.Reload object at 0x10441fef0>

2016-04-06T12:06:50: %UNICON-INFO: adding service  sendline   :  <unicon.plugins.generic.service_implementation.Sendline object at 0x10441ffd0>

2016-04-06T12:06:50: %UNICON-INFO: adding service  list_vdc   :  <unicon.plugins.nxos.service_implementation.ListVdc object at 0x10441f978>

2016-04-06T12:06:50: %UNICON-INFO: adding service  copy   :  <unicon.plugins.generic.service_implementation.Copy object at 0x10443b048>

2016-04-06T12:06:50: %UNICON-INFO: adding service  switchto   :  <unicon.plugins.nxos.service_implementation.SwitchVdc object at 0x10443b0b8>

2016-04-06T12:06:50: %UNICON-INFO: adding service  disable   :  <unicon.plugins.generic.service_implementation.Disable object at 0x10443b0f0>

2016-04-06T12:06:50: %UNICON-INFO: adding service  send   :  <unicon.plugins.generic.service_implementation.Send object at 0x10443b128>

2016-04-06T12:06:50: %UNICON-INFO: adding service  delete_vdc   :  <unicon.plugins.nxos.service_implementation.DeleteVdc object at 0x10443b160>

2016-04-06T12:06:50: %UNICON-INFO: adding service  ping6   :  <unicon.plugins.nxos.service_implementation.Ping6 object at 0x10443b198>

2016-04-06T12:06:50: %UNICON-INFO: adding service  execute   :  <unicon.plugins.generic.service_implementation.Execute object at 0x10443b208>

2016-04-06T12:06:50: %UNICON-INFO: adding service  enable   :  <unicon.plugins.generic.service_implementation.Enable object at 0x10443b240>

2016-04-06T12:06:50: %UNICON-INFO: adding service  shellexec   :  <unicon.plugins.nxos.service_implementation.ShellExec object at 0x10443b278>

2016-04-06T12:06:50: %UNICON-INFO: adding service  switchback   :  <unicon.plugins.nxos.service_implementation.SwitchbackVdc object at 0x10443b2b0>

2016-04-06T12:06:50: %UNICON-INFO: adding service  config   :  <unicon.plugins.generic.service_implementation.Config object at 0x10443b2e8>

2016-04-06T12:06:50: %UNICON-INFO: adding service  create_vdc   :  <unicon.plugins.nxos.service_implementation.CreateVdc object at 0x10443b320>

2016-04-06T12:06:50: %UNICON-INFO: adding service  expect   :  <unicon.plugins.generic.service_implementation.Expect object at 0x10443b358>

2016-04-06T12:06:50: %UNICON-INFO: adding service  log_user   :  <unicon.plugins.generic.service_implementation.LogUser object at 0x10443b390>

2016-04-06T12:06:50: %UNICON-INFO: connection to step-n7k-1

2016-04-06T12:06:50: %UNICON-INFO: +++ connection to spawn_command: telnet 10.64.70.24 2061, id: 4358177400 +++

2016-04-06T12:06:50: %UNICON-INFO: telnet 10.64.70.24 2061
Trying 10.64.70.24...
Connected to ts-nostg-mm18.cisco.com.
Escape character is '^]'.

step-n7k-1#
2016-04-06T12:06:51: %UNICON-INFO: +++ initializing handle +++

2016-04-06T12:06:51: %UNICON-INFO: +++ execute  +++
term length 0
step-n7k-1#
2016-04-06T12:06:51: %UNICON-INFO: +++ execute  +++
term width 511
step-n7k-1#
2016-04-06T12:06:51: %UNICON-INFO: +++ execute  +++
terminal session-timeout 0
step-n7k-1#
2016-04-06T12:06:51: %UNICON-INFO: +++ config  +++
config term
Enter configuration commands, one per line.  End with CNTL/Z.
step-n7k-1(config)# no logging console
step-n7k-1(config)# line console
step-n7k-1(config-console)# exec-timeout 0
step-n7k-1(config-console)# terminal width 511
step-n7k-1(config-console)# end
step-n7k-1#

Example: Linux Server

Specifying linux device in testbed file template is almost the same as router template, except Unicon looks for linux block in the device details and os has to be mentioned as linux

mohamoha-ads:
    os: 'linux'
    credentials:
        default:
            username: admin
            password: password
    connections:
      defaults:
        class: 'unicon.Unicon'
      linux:
        protocol: ssh
        ip: mohamoha-ads
    type: 'linux'

Connecting to linux machine using above testbed file:

>>> from pyats.topology import loader
>>> tb = loader.load("testbed.yaml")

>>> server = tb.devices['mohamoha-ads']

>>> server.connect()

2016-04-06T12:10:49: %UNICON-INFO: +++ initializing context +++

2016-04-06T12:10:49: %UNICON-INFO: +++ initializing state_machine +++

2016-04-06T12:10:49: %UNICON-INFO: +++ initializing services +++

2016-04-06T12:10:49: %UNICON-INFO: adding service  send   :  <unicon.plugins.generic.service_implementation.Send object at 0x10443b9b0>

2016-04-06T12:10:49: %UNICON-INFO: adding service  execute   :  <unicon.plugins.linux.service_implementation.Execute object at 0x10443be48>

2016-04-06T12:10:49: %UNICON-INFO: adding service  sendline   :  <unicon.plugins.generic.service_implementation.Sendline object at 0x10443be80>

2016-04-06T12:10:49: %UNICON-INFO: adding service  expect   :  <unicon.plugins.generic.service_implementation.Expect object at 0x10443beb8>

2016-04-06T12:10:49: %UNICON-INFO: adding service  log_user   :  <unicon.plugins.generic.service_implementation.LogUser object at 0x10443bef0>

2016-04-06T12:10:49: %UNICON-INFO: connection to mohamoha-ads

2016-04-06T12:10:49: %UNICON-INFO: +++ connection to spawn_command: ssh -l mohamoha 64.103.223.250, id: 4366516064 +++

2016-04-06T12:10:49: %UNICON-INFO: ssh -l mohamoha 64.103.223.250

Last login: Mon Apr  4 16:12:21 2016 from 10.232.8.212
Cisco Linux 5.50-5Server Kickstarted on: Sat Jun 13 05:53:15 PDT 2009.

bgl-ads-842:129>
2016-04-06T12:10:49: %UNICON-INFO: +++ initializing handle +++

2016-04-06T12:10:49: %UNICON-INFO: Attaching  all Subcommands

Connection to Linux with additional SSH options:

If you want to linux connection to take aditional ssh options, then it better to use command key. Unicon will take the value of command and spawns. Commond key should be the complete command to be spawned

mohamoha-ads:
    os: 'linux'
    credentials:
        default:
            username: admin
            password: password
    connections:
      defaults:
        class: 'unicon.Unicon'
      linux:
        command: 'ssh -l admin 10.1.1.1 -oHostKeyAlgorithms=+ssh-dss'
    type: 'linux'

Connecting to another TCP port using SSH:

If you want to connect to another port with SSH, you can use the port option in the testbed file:

lnx-vm:
    os: 'linux'
    credentials:
        default:
            username: admin
            password: password
    connections:
      defaults:
        class: 'unicon.Unicon'
      linux:
        protocol: ssh
        ip: 10.1.1.1
        port: 2200
    type: 'linux'

Example: Moonshine

Specifying a Moonshine device in the testbed file template is again very similar to the above examples, except Unicon looks for the iosxr os and moonshine type and series, and no username or password is required.

bringup:
  xrut:
    base_dir: /auto/xrut/xrut-gold
    sim_dir: /path/to/my/xrut/sim/dir
devices:
  moonshine-1:
    os: iosxr
    series: moonshine
    type: moonshine
    credentials:
        default:
            username: admin
            password: password
    connections:
      defaults: {class: unicon.XRUTConnect}
      a: {protocol: xrutconnect}

Please note that devices using the xrutconnect protocol should specify the default connection class as unicon.XRUTConnect.

For information on how to create such a testbed file via the xrutbringup command, passing in a logical testbed file and a clean.yaml file, please see dyntopo xrut working examples moonshine .

Example: NSO

To connect to the Network Service Orchestrator CLI via SSH, use the ‘nso’ OS type and specify the ssh port under the connection details.

# example testbed.yaml file for NSO CLI
devices:
  ncs:
    os: nso
    credentials:
      default:
          username: admin
          password: password
    connections:
      defaults:
        class: unicon.Unicon
        via: cli
      con:
        command: ncs_cli -C
      cli:
        credentials:
          nso:
              username: admin
              password: cisco1234
        login_creds: nso
        protocol: ssh
        ip: 127.0.0.1
        port: 2024

Connecting to NSO CLI via SSH using above testbed file:

As shown in the example below, use the connect() method to initiate the connection, specify the ‘via’ option if no default is configured under the connection defaults.

The ncs.conf configuration file section for the SSH service for NSO is shown below.

<cli>
  <enabled>true</enabled>
  <style>c</style>

  <!-- Use the builtin SSH server -->
  <ssh>
    <enabled>true</enabled>
    <ip>0.0.0.0</ip>
    <port>2024</port>
  </ssh>

This example uses the ‘cli’ connection which initiates a SSH session the to default port of the NSO SSH service.

>>> from pyats.topology import loader
>>> tb = loader.load("testbed.yaml")

>>> ncs = tb.devices.ncs

>>> ncs.connect(via='cli')

2017-06-02T08:15:55: %UNICON-INFO: +++ initializing context +++

2017-06-02T08:15:55: %UNICON-INFO: +++ initializing state_machine +++

2017-06-02T08:15:55: %UNICON-INFO: +++ initializing services +++

2017-06-02T08:15:55: %UNICON-INFO: adding service  execute   :  <unicon.plugins.nso.service_implementation.Execute object at 0x7ff3549ba630>

2017-06-02T08:15:55: %UNICON-INFO: adding service  cli_style   :  <unicon.plugins.nso.service_implementation.CliStyle object at 0x7ff3549ba668>

2017-06-02T08:15:55: %UNICON-INFO: adding service  log_user   :  <unicon.plugins.generic.service_implementation.LogUser object at 0x7ff3549ba6a0>

2017-06-02T08:15:55: %UNICON-INFO: adding service  sendline   :  <unicon.plugins.generic.service_implementation.Sendline object at 0x7ff3549ba6d8>

2017-06-02T08:15:55: %UNICON-INFO: adding service  expect   :  <unicon.plugins.generic.service_implementation.Expect object at 0x7ff3549ba710>

2017-06-02T08:15:55: %UNICON-INFO: adding service  configure   :  <unicon.plugins.nso.service_implementation.Configure object at 0x7ff3549ba748>

2017-06-02T08:15:55: %UNICON-INFO: adding service  send   :  <unicon.plugins.generic.service_implementation.Send object at 0x7ff3549ba780>

2017-06-02T08:15:55: %UNICON-INFO: connection to ncs

2017-06-02T08:15:55: %UNICON-INFO: +++ connection to spawn_command: ssh -l admin 127.0.0.1 -p 2024, id: 140683073268704 +++

2017-06-02T08:15:55: %UNICON-INFO: ssh -l admin 127.0.0.1 -p 2024
admin@127.0.0.1's password:

admin connected from 127.0.0.1 using ssh on nso-dev-server
admin@ncs#
2017-06-02T08:15:55: %UNICON-INFO: +++ initializing handle +++

2017-06-02T08:15:55: %UNICON-INFO: +++ None  +++
paginate false
admin@ncs#
2017-06-02T08:15:55: %UNICON-INFO: +++ execute  +++
screen-length 0
admin@ncs#
2017-06-02T08:15:55: %UNICON-INFO: +++ execute  +++
screen-width 0
admin@ncs#
2017-06-02T08:15:55: %UNICON-INFO: Attaching  all Subcommands
>>>

Connecting to NSO CLI via ncs_cli command using above testbed file

It is also possible to run the ncs_cli command to initiate the CLI session, use the ‘command’ option in the testbed.yaml file to specify the ncs_cli command.

Specify the ‘via’ option if the default is not specified in the connection defaults.

>>> ncs.connect(via='con')

2017-06-02T08:19:19: %UNICON-INFO: +++ initializing context +++

2017-06-02T08:19:19: %UNICON-INFO: +++ initializing state_machine +++

2017-06-02T08:19:19: %UNICON-INFO: +++ initializing services +++

2017-06-02T08:19:19: %UNICON-INFO: adding service  send   :  <unicon.plugins.generic.service_implementation.Send object at 0x7fab8e932320>

2017-06-02T08:19:19: %UNICON-INFO: adding service  log_user   :  <unicon.plugins.generic.service_implementation.LogUser object at 0x7fab8e932358>

2017-06-02T08:19:19: %UNICON-INFO: adding service  configure   :  <unicon.plugins.nso.service_implementation.Configure object at 0x7fab8e932390>

2017-06-02T08:19:19: %UNICON-INFO: adding service  cli_style   :  <unicon.plugins.nso.service_implementation.CliStyle object at 0x7fab8e9323c8>

2017-06-02T08:19:19: %UNICON-INFO: adding service  execute   :  <unicon.plugins.nso.service_implementation.Execute object at 0x7fab8e932400>

2017-06-02T08:19:19: %UNICON-INFO: adding service  sendline   :  <unicon.plugins.generic.service_implementation.Sendline object at 0x7fab8e932438>

2017-06-02T08:19:19: %UNICON-INFO: adding service  expect   :  <unicon.plugins.generic.service_implementation.Expect object at 0x7fab8e932470>

2017-06-02T08:19:19: %UNICON-INFO: connection to ncs

2017-06-02T08:19:19: %UNICON-INFO: +++ connection to spawn_command: ncs_cli -C, id: 140374808144136 +++

2017-06-02T08:19:19: %UNICON-INFO: ncs_cli -C

dwapstra connected from 10.0.2.2 using ssh on nso-dev-server
dwapstra@ncs#
2017-06-02T08:19:19: %UNICON-INFO: +++ initializing handle +++

2017-06-02T08:19:19: %UNICON-INFO: +++ None  +++
paginate false
dwapstra@ncs#
2017-06-02T08:19:19: %UNICON-INFO: +++ execute  +++
screen-length 0
dwapstra@ncs#
2017-06-02T08:19:19: %UNICON-INFO: +++ execute  +++
screen-width 0
dwapstra@ncs#
2017-06-02T08:19:19: %UNICON-INFO: Attaching  all Subcommands

Example: ConfD

To connect to ConfD based CLI via SSH, use the ‘confd’ OS type and specify the ssh port (if needed) under the connection details.

For NSO, the ‘os’ needs to be specified, ‘series’ can be omitted. For CSP, ESC and NFVIS, the ‘series’ needs to be specified.

# example testbed.yaml file for NSO CLI
devices:
  ncs:
    os: confd
    type: router
    # series: 'csp', 'esc' or 'nfvis'
    credentials:
      default:
          username: admin
          password: cisco1234
    connections:
      defaults:
        class: unicon.Unicon
        via: cli
      cli:
        protocol: ssh
        ip: 127.0.0.1
        port: 2024

Example: VOS

To connect to Cisco Unified Collaboration based CLI via SSH, use the ‘vos’ OS type and specify the ssh port (if needed) under the connection details.

# example testbed.yaml file for VOS CLI
devices:
  cm:
    os: vos
    type: server
    credentials:
      default:
          username: admin
          password: cisco1234
    connections:
      defaults:
        class: unicon.Unicon
        via: cli
      cli:
        protocol: ssh
        ip: 10.0.0.1
        port: 22

pyATS Connection Pool

Unicon (IOSXE, NXOS and IOSXR) plugins now support creating a pool of shareable connections to be distributed among device action requests promoting speed and avoiding race condition and deadlocks.

# Example
# -------
#
# Connection pool using unicon.Unicon class example
# Assuming we have a device that is defined in the testbed yaml file as above

# using the above device, create a pool of 5 workers
>>> device.start_pool(alias = 'pool', ----- > Connection pool will be accessed as "device.pool"
                      via = 'mgmt',   ----- > Connection name as in testbed yaml
                      size = 5)

# Now all action requests sent to the device will run simultaneously on the
# 5 connections (knows as workers) on a first come first serve basis.

Check here for more details on pyATS Connection Pool feature.

Python APIs

This section covers how to connect to a device in standalone mode, using raw Python APIs directly.

To connect to a device, you need.
  • IP address

  • Hostname

  • OS

  • Credentials

Please make sure that device is up and booted. In the following example, we are establishing connection to a dual rp NXOS device.

from unicon import Connection
dev = Connection(hostname='n7k2-1',
                 start=['telnet 172.27.114.43 2037',
                        'telnet 172.27.114.43 2038'],
                 credentials={'default': {'username': 'admin', 'password': 'Cisc0123'}},
                 os='nxos')
dev.connect()

Arguments:

  • hostname: must be same as the exact hostname of the device. Do not append prompt characters like ‘#’ or ‘$’

  • os: The os of the device to connect to. This selects a unicon plugin.

  • start: It must be a list of commands which needs to be invoked for starting a connection. Generally it will be of the format telnet xxx xxx. But it could take any value.

  • credentials: A dictionary of named credentials used to interact with the device.

  • series: The series of the device to connect to. This selects a unicon sub-plugin under the given plugin identified with the os argument. (Optional)

  • model: The model of the device to connect to. This selects a unicon sub-sub-plugin under the given plugin identified with the os and series arguments. (Optional)

  • connection_timeout: Connection timeout value to connect the device. Default value is 60 sec. (Optional)

  • proxy_connections: Connection object which is use to establish proxy connection. Default value is None. (Optional)

  • alias: Connection alias. Default value is None. (Optional)

  • login_creds: A single credential name or a list of credentials for authenticating against the device. Default value is default. (Optional)

  • learn_hostname: Set to True if the actual hostname set on the device differs from the hostname parameter. (Optional)

  • learn_os: Set to True if the device os is not provided, it will try to learn the device os and redirect to the learned plugin. (Optional)

  • prompt_recovery: Set True for using prompt recovery feature. Default value is False. Click Prompt Recovery Feature for more information on the feature. (Optional)

  • init_exec_commands: List of exec commands to use when initializing the connection. This option overrules the default settings for the plugin and uses the user specified initialization commands. Can also be passed in the connection block in the yaml file. (Optional)

  • init_config_commands: List of config commands to use when initializing the connection. This option overrules the default settings for the plugin and uses the user specified initialization commands. Config commands will not be executed on the standby RP. Config commands are not available on Linux and ISE plugins. Can also be passed in the connection block in the yaml file. (Optional)

  • logfile: Filename to log all device interaction to. (Optional)

  • mit: Boolean option to maintain initial state on connect. The state detected on connect() is maintained, no connection initialization is done and the exec and config initialization commands are not executed. It is possible to use the mit option with HA connections, however please note that HA initialization is not done. Default is False. (Optional)

  • settings: Dictionary or Settings class instance with updated settings for this connection. Pass a dictionary to update some of the settings, or pass a Settings object with all settings. (Optional)

  • log_stdout: Boolean option to enable/disable logging to standard output. Default is True. (Optional)

  • debug: Boolean option to enable/disable internal debug logging. (Optional)

  • service_attributes: Dictionary whose keys are service names and whose values are dictionaries containing key/value pairs to set on the named service. (Optional)

  • connect_reply: Dialog object which user wants to be added in the connection dialog. (Optional)

  • goto_enable: Boolean option to enable/disable connection behavior to go to enable state after setting up connection. Default is True. (Optional)

  • standby_goto_enable: Boolean option to enable/disable standby connection behavior to go to enable state after setting up connection. Default is True. (Optional)

For Single RP connection, start will be a list with only one element.

Note

Connecting to many routing and switching platforms usually requires the configured hostname to be known in advance. However, sometimes the configured hostname on such a device may be unknown and may differ from the hostname parameter.

When learn_hostname=True is specified:

  • unicon attempts to learn the hostname of the device by examining the device’s prompt.

  • If no hostname can be learned, a warning is thrown and the learned hostname is set to a generic pattern.

  • If the learned hostname differs from the hostname parameter, dev.previous_hostname is set to the original hostname and dev.hostname is overwritten with the newly learned hostname.

  • Once set, the learn_hostname setting can only be changed by destroying and recreating the Connection object.

  • The hostname of the device does not contain the characters : #, whitespace characters.

Note

When using the Linux plugin, it is recommended to use learn_hostname=True. With the default prompt pattern for the Linux plugin there is a risk of false prompt matching if the output contains one of the prompt characters > # % ~ $ at the end of a line.

Disconnecting

To disconnect a session, you can call the disconnect() method from a Unicon connection. This will terminate the subprocess that is handling the device connection. By default, Unicon waits about 10 seconds after the process is terminated before returning from the method. This is to prevent connection issues on rapid connect/disconnect sequences.

To change the default timers used when disconnecting, you can change the GRACEFUL_DISCONNECT_WAIT_SEC and POST_DISCONNECT_WAIT_SEC settings on the Settings object.

dev.settings.GRACEFUL_DISCONNECT_WAIT_SEC = 0
dev.settings.POST_DISCONNECT_WAIT_SEC = 0

Extend Settings Attributes

It is possible to extend list settings attributes of the connection like ERROR_PATTERN and CONFIGURE_ERROR_PATTERN by using overwrite_settings=False argument.

from unicon import Connection
settings = {'ERROR_PATTERN': ['test', 'error']}
dev = Connection(hostname='asr1000',
                 start=['telnet 172.27.114.43 2037'],
                 credentials={'default': {'username': 'admin', 'password': 'Cisc0123'}},
                 os='iosxe',
                 settings=settings,
                 overwrite_settings=False)
dev.connect()
dev.settings.ERROR_PATTERN
['test',
 'error',
 '^%\\s*[Ii]nvalid (command|input)',
 '^%\\s*[Ii]ncomplete (command|input)',
 '^%\\s*[Aa]mbiguous (command|input)']

# this can be done from testbed yaml as well
# the following is an example testbed
devices:
  PE1:
    alias: uut
    os: iosxe
    credentials:
      default:
        password: cisco
        username: admin
      enable:
        password: cisco
    connections:
      defaults:
        class: unicon.Unicon
      a:
        protocol: telnet
        ip: 1.1.1.1
        port: 2039
        arguments:
          overwrite_settings: False
        settings:
          EXEC_TIMEOUT: 300
          ERROR_PATTERN:
            - testbed
            - my ERROR

Overriding Service Attributes

When a connection is created, various services are attached to it. The selected plugin determines the list of supported services.

It is possible to override attributes of one or more services by specifying the service_attributes parameter.

from unicon import Connection
dev = Connection(hostname='n7k2-1',
                 start=['telnet 172.27.114.43 2037'],
                 credentials={'default': {'username': 'admin', 'password': 'Cisc0123'}},
                 os='nxos',
                 service_attributes=dict(
                    traceroute=dict(timeout=123),
                    ping=dict(timeout=456)))
dev.connect()
dev.traceroute.timeout
123
dev.ping.timeout
456

Credentials

The credentials connection parameter defines a dictionary of named credentials. A credential is a dictionary typically containing both username and password keys.

The login_creds connection parameter defines an optional sequence of credential names to try. Each time the device prompts for a username or password, the current credential is set to the next credential in the sequence if a current credential has not already been set. When a password is sent, the current credential is unset. The one exception is when entering an administrator’s password on a routing device coming up without configuration, in this case the current credential is reused. If the sequence has been exhausted and no more credentials are available to satisfy a username/password prompt, a CredentialsExhaustedError is raised.

Credentials are not retried, any username or password failure causes a UniconAuthenticationError to be raised.

It is possible to specify the password to use for routing devices to enter enable mode. This may be done via the enable_password entry under the current credential, or via a separate credential called enable. Please see Enable password handling for details.

Passwords specified as a Secret Strings are automatically decoded prior to being sent to the device.

In pyATS Testbed YAML

Credentials may be specified on a per-testbed, per-device or per-connection basis, as documented in Credential Password Modeling.

from pyats.topology import loader
tb = loader.load("""
    devices:
        my_device:
            type: router
            credentials:
                default:
                    username: admin
                    password: Cisc0123
                alternate:
                    username: alt_username
                    password: alt_password
                termserv:
                    username: tsuser
                    password: tspw
                enable:
                    password: enablepw
            connections:
                defaults: {class: 'unicon.Unicon'}
                a:
                  protocol: ssh
                  ip: 10.64.70.11
                  port: 2042
                  login_creds: [termserv, default]

""")
dev = tb.devices.my_device
dev.connect()

# To connect using different credentials than is contained in the
# testbed YAML ``login_creds`` key:
dev.destroy()
dev.connect(login_creds=['termserv', 'alternate'])

In Python

dev = Connnection(hostname=uut_hostname,
                   start=[uut_start_cmd],
                   credentials={\
                       {'default': {'username': 'admin', 'password': 'Cisc0123'}},\
                       {'enable': {'password': 'enablepw'}},\
                       {'termserv': {'username': 'tsuser', 'password': 'tspw'}},\
                   },
                   login_creds = ['termserv', 'default'],
                 )

Logging

Every unicon device connection Logger has 3 handlers.

  1. Screen Handler: This logs messages on stdout

  2. File Handler: This logs messages in file /tmp/<device>-<alias>-<timestamp>.log. This is default log file. To modify the file value, the logfile parameter can be used.

  3. pyATS TaskLog Handler: This logs messages in pyats TaskLog file

Change logfile when connecting.

In unicon standalone mode:

dev = Connnection(hostname=uut_hostname,
                   start=[uut_start_cmd],
                   logfile='user-provided-file')

With pyATS:

dev.connect(logfile='user-provided-file')

Log level of device output and service messages is INFO.

To disable unicon device conneciton logging, we can set logger level above logging.INFO.

import logging
uut.log.setLevel(logging.WARNING)

To enable debug logs, use below:

import logging
uut.log.setLevel(logging.DEBUG)

Debug log now intergrate with pyATS testbed yaml file. You can enable it by define the debug: True in the yaml file:

devices:
  PE1:
    connections:
      defaults:
        class: 'unicon.Unicon'
        debug: True

To disable logging to standard output, use the log_stdout boolean option.

In unicon standalone mode:

dev = Connnection(hostname=uut_hostname,
                   start=[uut_start_cmd],
                   log_stdout=False)

With pyATS:

dev.connect(log_stdout=False)

Prompt Recovery Usage

In unicon, device connection is 2 step process:

  1. Create Device Connection object

  2. Invoke connect() on Device Connection object.

The prompt_recovery is valid for per connect() call. To use prompt_recovery feature user need to specify it per call i.e when connecting next time, user need to set it again as True.

Examples:

To use prompt_recovery feature in unicon, use it in the following way:

from unicon import Connection
device = Connection(hostname='R2', start=['telnet localhost 15000'], prompt_recovery=True)
device.connect()

If user wish to enable prompt_recovery after creating Device Connection object, it can be done in the following way:

from unicon import Connection
device = Connection(hostname='R2', start=['telnet localhost 15000'])
device.context.prompt_recovery=True
device.connect()

When using with pyats, the feature can be used in the following way:

device = testbed['R1']
device.connect(prompt_recovery=True)

In pyats, to use prompt_recovery in next connect() call, use device.destroy() to disconnect connection and use device.connect(prompt_recovery=True) again.

Login and Password Prompts

Unicon generic plugin uses the following regular expressions to match login and password prompts:

  1. Login pattern: r'^.*([Uu]sername|[Ll]ogin): ?$'

  2. Password pattern: r'^.*[Pp]assword( for )?(S+)?: ?$'

While creating a connection, Unicon sends username and password when the device prompt matches the above patterns.

In some cases, change in login/password prompts on device may lead to connection failure if the default patterns no longer match.

To handle such situations, user can provide custom regular expression pattern to match with different login and password prompts on the device.

It can be done by setting regular expression to LOGIN_PROMPT and PASSWORD_PROMPT attributes of device settings.

Example:

# Unicon standalone mode
dev = Connection(hostname='R2', start=['telnet x.x.x.x'],\
    credentials={{'default': {'username': 'admin', 'password': 'Cisc0123'}})
dev.settings.LOGIN_PROMPT = r'USERNAME:\s?$'
dev.settings.PASSWORD_PROMPT = r'PASSWORD:\s$'

In pyATS testbed yaml file, this can be set in the following way:

devices:
  R2
    credentials:
        default:
            username: admin
            password: Cisc0123
    connections:
      defaults: {class: 'unicon.Unicon'}
      a:
        protocol: telnet
        ip: x.x.x.x
        port: 2042
        prompts:
            login: r'USERNAME:\s?$'
            password: r'PASSWORD:\s$'

The login and password patterns are also applicable for login/password prompts displayed during reload(), switchover() and execute() services. It is possible to override the login and password dialogs and other default dialogs in the execute service by specifying the service_dialog option in the execute statement. See execute service.

This setting attribute are not applicable for ise plugin.

These settings attributes are supported on below plugins:

  1. generic

  2. iosxr

  3. junos

  4. linux

  5. aireos

Learn Device OS

Unicon generic plugin now can learn the device os/series and redirect the connection to use corresponding plugins. This can be done if you pass learn_os argument in device.connect(learn_os=True).

Example:

In pyATS testbed.yaml file, no os is provided:

devices:
  Router:
    alias: uut
    type: xe
    credentials:
      default:
        password: cisco
        username: cisco
      enable:
        password: cisco
    connections:
      defaults:
        class: unicon.Unicon
      a:
        protocol: telnet
        ip: x.x.x.x
        port: xxxx

In pyATS shell:

# pyats shell --testbed-file testbed.yaml
>>> from genie.testbed import load
>>> testbed = load('testbed.yaml')
-------------------------------------------------------------------------------
>>> dev = testbed.devices['uut']
>>> dev.connect(learn_os=True)
# dev.connect()  << if learn_os is not provided, then it will use generic plugin


device's os is not provided, unicon may not use correct plugins

2020-08-11 16:17:37,909: %UNICON-INFO: +++ Router logfile /tmp/Router-cli-20200811T161737899.log +++

2020-08-11 16:17:37,910: %UNICON-INFO: +++ Unicon plugin generic +++
Trying x.x.x.x...


2020-08-11 16:17:37,951: %UNICON-INFO: +++ connection to spawn: telnet x.x.x.x xxxx, id: 140643774849992 +++

2020-08-11 16:17:37,952: %UNICON-INFO: connection to Router

2020-08-11 16:17:37,952: %UNICON-INFO: Learning device Router os
Connected to x.x.x.x.
Escape character is '^]'.

Router#

2020-08-11 16:17:38,543: %UNICON-INFO: +++ Router: executing command 'show version' +++
show version
Cisco IOS Software, IOS-XE Software (PPC_LINUX_IOSD-ADVIPSERVICES-M), Version 15.2(4)S, RELEASE SOFTWARE (fc4)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2012 by Cisco Systems, Inc.
Compiled Mon 23-Jul-12 19:02 by mcpre

IOS XE Version: 03.07.00.S

Cisco IOS-XE software, Copyright (c) 2005-2012 by cisco Systems, Inc.
All rights reserved.  Certain components of Cisco IOS-XE software are
licensed under the GNU General Public License ("GPL") Version 2.0.  The
software code licensed under GPL Version 2.0 is free software that comes
with ABSOLUTELY NO WARRANTY.  You can redistribute and/or modify such
GPL code under the terms of GPL Version 2.0.  For more details, see the
documentation or "License Notice" file accompanying the IOS-XE software,
or the applicable URL provided on the flyer accompanying the IOS-XE
software.


ROM: IOS-XE ROMMON

Router uptime is 31 weeks, 2 hours, 15 minutes
Uptime for this control processor is 31 weeks, 2 hours, 18 minutes
System returned to ROM by reload
System image file is "bootflash:asr1000rp1-advipservices.03.07.00.S.152-4.S.bin"
Last reload reason: PowerOn


cisco Router-F (2RU) processor with 1698793K/6147K bytes of memory.
Processor board ID FOX1405GDVK
12 Gigabit Ethernet interfaces
32768K bytes of non-volatile configuration memory.
4194304K bytes of physical memory.
7798783K bytes of eUSB flash at bootflash:.

Configuration register is 0x2102

Router#

2020-08-11 16:17:40,221: %UNICON-INFO: Learned device os: iosxe

2020-08-11 16:17:40,222: %UNICON-INFO:
Learned device os: iosxe
Redirect to corresponding plugins.

2020-08-11 16:17:52,263: %UNICON-INFO: +++ Router logfile /tmp/Router-cli-20200811T161752253.log +++

2020-08-11 16:17:52,263: %UNICON-INFO: +++ Unicon plugin iosxe +++
Trying x.x.x.x...


2020-08-11 16:17:52,288: %UNICON-INFO: +++ connection to spawn: telnet x.x.x.x xxxx, id: 140643774387984 +++

2020-08-11 16:17:52,288: %UNICON-INFO: connection to Router
Connected to x.x.x.x.
Escape character is '^]'.

Router#

2020-08-11 16:17:52,896: %UNICON-INFO: +++ initializing handle +++

2020-08-11 16:17:52,897: %UNICON-INFO: +++ Router: executing command 'term length 0' +++
term length 0
Router#

2020-08-11 16:17:53,113: %UNICON-INFO: +++ Router: executing command 'term width 0' +++
term width 0
Router#

2020-08-11 16:17:53,310: %UNICON-INFO: +++ Router: executing command 'show version' +++
show version
Cisco IOS Software, IOS-XE Software (PPC_LINUX_IOSD-ADVIPSERVICES-M), Version 15.2(4)S, RELEASE SOFTWARE (fc4)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2012 by Cisco Systems, Inc.
Compiled Mon 23-Jul-12 19:02 by mcpre

IOS XE Version: 03.07.00.S

Cisco IOS-XE software, Copyright (c) 2005-2012 by cisco Systems, Inc.
All rights reserved.  Certain components of Cisco IOS-XE software are
licensed under the GNU General Public License ("GPL") Version 2.0.  The
software code licensed under GPL Version 2.0 is free software that comes
with ABSOLUTELY NO WARRANTY.  You can redistribute and/or modify such
GPL code under the terms of GPL Version 2.0.  For more details, see the
documentation or "License Notice" file accompanying the IOS-XE software,
or the applicable URL provided on the flyer accompanying the IOS-XE
software.


ROM: IOS-XE ROMMON

Router uptime is 31 weeks, 2 hours, 15 minutes
Uptime for this control processor is 31 weeks, 2 hours, 18 minutes
System returned to ROM by reload
System image file is "bootflash:asr1000rp1-advipservices.03.07.00.S.152-4.S.bin"
Last reload reason: PowerOn


cisco Router-F (2RU) processor with 1698793K/6147K bytes of memory.
Processor board ID FOX1405GDVK
12 Gigabit Ethernet interfaces
32768K bytes of non-volatile configuration memory.
4194304K bytes of physical memory.
7798783K bytes of eUSB flash at bootflash:.

Configuration register is 0x2102

Router#

2020-08-11 16:17:55,027: %UNICON-INFO: +++ Router: config +++
config term
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#no logging console
Router(config)#line console 0
Router(config-line)#exec-timeout 0
Router(config-line)#end
Router#