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NTC TEMPLATES

Repository of TextFSM Templates for Network Devices, and Python wrapper for TextFSM's CliTable.

TextFSM is a project built by Google that takes CLI string output and passes each line through a series of regular expressions until it finds a match. The regular expressions use named capture groups to build a text table out of the significant text. The names of the capture groups are used as column headers, and the captured values are stored as rows in the table.

This project provides a large collection of TextFSM Templates (text parsers) for a variety of Networking Vendors. In addition to the templates, there is a function that will convert the CLI output into a CliTable object; the resulting text table is converted into a list of dictionaries mapping the column headers with each row in the table.

Installation and Usage

The project can be installed using either Git or PyPI; if you would like to use the templates outside of this project, then Git is the recommended approach.

Git

$ git clone [email protected]:networktocode/ntc-templates.git
$ 
# Optional steps to install ntc-templates as a python package
$ pip install -e ntc-templates/
$

The install can also include the required dev packages, which can be useful for adding or editing templates:

$ git clone [email protected]:networktocode/ntc-templates.git
$ 
# Optional steps to install ntc-templates as a python package
$ pip install -e ntc-templates/[dev]
$

PyPI

$ pip install ntc_templates
$

To include the dev packages:

$ pip install ntc_templates[dev]
$

Usage

>>> from ntc_templates.parse import parse_output
>>> vlan_output = (
        "VLAN Name                             Status    Ports\n"
        "---- -------------------------------- --------- -------------------------------\n"
        "1    default                          active    Gi0/1\n"
        "10   Management                       active    \n"
        "50   VLan50                           active    Fa0/1, Fa0/2, Fa0/3, Fa0/4, Fa0/5,\n"
        "                                                Fa0/6, Fa0/7, Fa0/8\n"
    )
>>> vlan_parsed = parse_output(platform="cisco_ios", command="show vlan", data=vlan_output)
>>> vlan_parsed
[
    {
        'vlan_id': '1',
        'name': 'default',
        'status': 'active',
        'interfaces': ['Gi0/1']
    },
    {
        'vlan_id': '10',
        'name': 'Management',
        'status': 'active',
        'interfaces': []
    },
    {
        'vlan_id': '50',
        'name': 'VLan50', 'status': 'active',
        'interfaces': ['Fa0/1', 'Fa0/2', 'Fa0/3', 'Fa0/4', 'Fa0/5', 'Fa0/6', 'Fa0/7', 'Fa0/8']
    }
]
>>>

Contributing

Pull requests are welcomed and automatically built and tested through TravisCI.

New Templates

To contribute new templates, each new pull request must include the following:

  • TextFSM template
  • Modified version of the index file
  • Tests
    • Raw version of text to be parsed
    • YAML file containing the expected parsed dictionary

TextFSM Template

TextFSM templates should be placed in the ./templates directory and should adhere to the following NTC-Templates style. The TextFSM template name should be in the following format:

Naming

The template should be named using: {{ vendor_os }}_{{ command_with_underscores }}.textfsm

Ex: cisco_ios_show_cdp_neighbors.textfsm

Note: The vendor name must be valid from the os_choices tests, which is primarily based on Netmiko list of supported vendors. New vendors added should adhere to vendor_os.

Ex: vmware_nsx

Values

The capture group names should be in UPPERCASE.

An example of the proper format is shown below.

Value TIME (\d+:\d+:\d+)
Value TIMEZONE (\S+)
Value DAYWEEK (\w+)
Value MONTH (\d+)
Value DAY (\d+)
Value YEAR (\d+)

Start
  ^${TIME}\s+${TIMEZONE}\s+${DAYWEEK}\s+${DAY}/${MONTH}/${YEAR} -> Record
  ^. -> Error
States

If the raw output has a heading, the Start state should match on the column headings and then transition to another state that will match the device's output table with the capture groups. This helps ensure the regex patterns for the capture groups are attempting to match the correct information, and allows templates to easily add additional States for tables that have different headings. Example:

Raw Output

... omitted
Network Next Hop Metric LocPrf Weight Path
*> 111.111.111.111/32 112.112.112.112 4294967295 4294967295 65535 1000 1000 1000 i

Sample Template

Start
# Checking for header
^\s*Network\s+Next(?:\s+|-)[Hh]op\s+Metric\s+LocPrf\s+Weight\s+Path\s*$$ -> BGPTable

BGPTable
 ... omitted

Each state should end with ^. -> Error. This helps to ensure we're accounting for every line within the raw output for the command. This doesn't mean we have to capture all the data as a Value, but we do have to account for it. In addition, it is also good to provide an expression to match blank lines, ^\s*$$

An example would be the following raw output:

NAME: "3640 chassis", DESCR: "3640 chassis"
PID: , VID: 0xFF, SN: FF1045C5

The template would be the following:

Value NAME (.*)
Value DESCRIPTION (.*)

Start
  ^NAME:\s+"${NAME}",\s*DESCR:\s+"${DESCRIPTION}"
  ^PID:\s*,\s*VID:\s*\S+,\s*SN:\s*\S+
  ^\s*$$
  ^. -> Error

Taking a look at the example template above, you notice that we're using \s* and \s+. These are the preferred way to match space characters, and should be used over the literal space character. For example, This\s+is\s+preferred\s*$$ vs This is not preferred$$

  • \s* accounts for zero or more spaces (use when the output may or may not have a space between characters)
  • \s+ accounts for one or more spaces (use when output will have a space, but could have more than one space)

Index File

The Index file binds the templates to the commands being run. Special care has been taken on ordering, as there is potential for issues. e.g. show ip route picking up for show ip router vrf <vrf-name>. We have used a combination of ordering, as defined:

  • OS in alphabetical order
  • Template name in length order
  • When length is the same, use alphabetical order of command name
  • Keep space between OS's

Example:

Template, Hostname, Platform, Command

# same os, same length, used alphabetical order of command name
arista_eos_show_mlag.textfsm, .*, arista_eos, sh[[ow]] ml[[ag]]
arista_eos_show_vlan.textfsm, .*, arista_eos, sh[[ow]] vl[[an]]

# os in alphabetical order and space between cisco_asa and arista_eos
cisco_asa_dir.textfsm,  .*, cisco_asa, dir

# same os, template name length different and space between cisco_asa and cisco_ios
cisco_ios_show_capability_feature_routing.textfsm,  .*, cisco_ios, sh[[ow]] cap[[ability]] f[[eature]] r[[outing]]
cisco_ios_show_interface_transceiver.textfsm, .*, cisco_ios, sh[[ow]] int[[erface]] trans[[ceiver]]
cisco_ios_show_cdp_neighbors_detail.textfsm, .*, cisco_ios, sh[[ow]] c[[dp]] neig[[hbors]] det[[ail]]

Tests

Tests will be located in ./tests with the following hierarchy:

  • ./tests/{{ vendor_os }}/{{ command_name }}/

The {{ command_name }} directory should include the .raw file that includes the raw output of the command to be parsed, and the .yml file of the returned structured data.

$ ls tests/cisco_ios/show_clock/
cisco_ios_show_clock.yml
cisco_ios_show_clock.raw
$
Raw version of input text

The raw text file should contain only the output of the CLI command to be parsed. It should not contain the CLI command itself.

An example of the proper format is shown below:

$ cat tests/cisco_ios/show_clock/cisco_ios_show_clock.raw
*18:57:38.347 UTC Mon Oct 19 2015
$
YAML file containing expected parsed dictionary

The parsed file should match the data that is returned from the parse_output function discussed in the beginning. Dictionary keys should be in lowercase.

The parsed text file should be placed in a directory in the ./tests directory with the same name as the template file but replace .textfsm file extension with .yml. The raw text file and the parsed text file should be in the same directory. ex. ./tests/cisco_ios/show_clock/

There are available helpers to create the parsed file in the correct format (See Development Helper Scripts below).

An example of the proper format is shown below:

$ cat ./tests/cisco_ios/show_clock/cisco_ios_show_clock.yml
---
parsed_sample:
  - time: "18:57:38.347"
    timezone: "UTC"
    dayweek: "Mon"
    month: "Oct"
    day: "19"
    year: "2015"
$

Multiple raw and parsed files are supported per directory, and are encouraged, as there are differences depending on version, length, etc. Additional test files and more real life data helps ensure backwards compatibility is maintained as each template is updated and merged into the repo.

All YAML files must adhere to the YAML standards defined in the .yamllint file in the root directory. Yamllint provides thorough documentation of their configuration settings here.

Development Helper Scripts

A cli utility is provided to assist with properly building the parsed files. This utility depends on some packages listed in the dev install requirements; see Install and Usage for directions on installing the dev requirements. All arguments that can be passed to the script are mutually exclusive (i.e. you can only pass one argument). The file can be made executable with the chmod +x development_scripts.py command. The arguments are:

  • -y: Takes the path to a YAML file and ensures that the file adheres to the .yamllint settings
  • -yd: Takes a glob path to a directory or directories that will ensure all files ending in .yml adhere to the .yamllint settings
  • -c: Takes the path to a .raw file, and generates the parsed data and saves the results adjacent to the .raw file following the defined standards in .yamllint.
  • -cd: Takes a glob path to a directory or directories containing .raw files, and creates the appropriate parsed files in the appropriate directory.

The -y and -yd arguments are designed to allow developers to generate the expected parsed file how they want, and ensure that the formatting adheres to the defined standard for this project.

The -c and -cd arguments use lib.ntc_templates.parse.parse_output() to generate the parsed data; this means that you can use these arguments to auto-generate the test .yml file(s) for new templates; just be sure that the template's parsing behavior meets expectations. In order for the data to be parsed, the template must be placed in templates/ and the templates/index file must be updated to correctly point to the template file(s).

$ /development_scripts.py -yd tests/cisco_ios/show_mac-address-table
tests/cisco_ios/show_mac-address-table/cisco_ios_show_mac-address-table2.yml
tests/cisco_ios/show_mac-address-table/cisco_ios_show_mac-address-table3.yml
tests/cisco_ios/show_mac-address-table/cisco_ios_show_mac-address-table5.yml
tests/cisco_ios/show_mac-address-table/cisco_ios_show_mac-address-table4.yml
tests/cisco_ios/show_mac-address-table/cisco_ios_show_mac-address-table.yml
$
$ ls tests/arista_eos/show_version/
arista_eos_show_version.raw
$
$ ./development_scripts.py -c tests/arista_eos/show_version/arista_eos_show_version.txt
$ ls tests/arista_eos/show_version/
arista_eos_show_version.raw   arista_eos_show_version.yml
$

Updating/Fixing Existing Templates

When either fixing a bug within a template or adding additional Values to be captured, additional test files should be added to ensure backwards compatibility and that the new data is being parsed correctly.

To add additional raw/parsed tests for a command:

  • Navigate to ./tests/{{ vendor_os }}/{{ command_name }}/
  • Create new .raw and .yml files within the directory, preferrably with a name identifying why the data is unique:
    • Existing raw: ./tests/cisco_ios/show_version/cisco_ios_show_version.raw
    • New raw: ./tests/cisco_ios/show_version/cisco_ios_show_version_stack_platforms.raw
    • Existing parsed: ./tests/cisco_ios/show_version/cisco_ios_show_version.yml
    • New parsed: ./tests/cisco_ios/show_version/cisco_ios_show_version_stack_platforms.yml

Testing

You can test your changes locally within your Git branch before submitting a PR. If you do not have tox already installed, you can do that using pip or your systems package manager. Tox should be ran inside the ntc-templates root directory. The tox file is configured to run against python3.6, so either python3.6 needs to be available, or the tox.ini file will need to be updated with an available Python version.

$ tox
GLOB sdist-make: /home/admin/ntc-templates/setup.py
py36 inst-nodeps: /home/admin/ntc-templates/.tox/dist/ntc_templates-1.3.0.zip
py36 installed: appdirs==1.4.3,atomicwrites==1.3.0,attrs==19.3.0,black==19.10b0,Click==7.0,future==0.18.2,importlib-metadata==0.23,more-itertools==7.2.0,ntc-templates==1.3.0,packaging==19.2,pathspec==0.6.0,pluggy==0.13.0,py==1.8.0,pyparsing==2.4.5,pytest==5.2.4,PyYAML==5.1.2,regex==2019.11.1,six==1.13.0,terminal==0.4.0,textfsm==1.1.0,toml==0.10.0,typed-ast==1.4.0,wcwidth==0.1.7,yamllint==1.18.0,zipp==0.6.0
py36 runtests: PYTHONHASHSEED='3677750645'
py36 runtests: commands[0] | black ./ --diff --check
All done! ✨ 🍰 ✨
8 files would be left unchanged.
py36 runtests: commands[1] | yamllint tests/
py36 runtests: commands[2] | pytest -vv
================================================================ test session starts =================================================================
platform linux -- Python 3.6.8, pytest-5.2.4, py-1.8.0, pluggy-0.13.0 -- /home/jmcgill/repos/ntc-templates/.tox/py36/bin/python3.6
cachedir: .pytest_cache
rootdir: /home/jmcgill/repos/ntc-templates
collected 428 items                                                                                                                                  

tests/test_index_order.py::test_index_ordering PASSED                                                                                          [  0%]
tests/test_structured_data_against_parsed_reference_files.py::test_raw_data_against_mock[tests/alcatel_sros/oam_mac-ping/alcatel_sros_oam_mac-ping.raw] PASSED [  0%]
tests/test_structured_data_against_parsed_reference_files.py::test_raw_data_against_mock[tests/alcatel_sros/show_service_id_base/alcatel_sros_show_service_id_base.raw] PASSED [  0%]
tests/test_structured_data_against_parsed_reference_files.py::test_raw_data_against_mock[tests/alcatel_sros/show_router_bgp_routes_vpn-ipv4/alcatel_sros_show_router_bgp_routes_vpn-ipv4.raw] PASSED [  0%]
tests/test_structured_data_against_parsed_reference_files.py::test_raw_data_against_mock[tests/brocade_fastiron/show_lldp_neighbors/brocade_fastiron_show_lldp_neighbors.raw] PASSED [  1%]
...
tests/test_structured_data_against_parsed_reference_files.py::test_raw_data_against_mock[tests/cisco_nxos/show_ip_interface_brief/cisco_nxos_show_ip_interface_brief.raw] PASSED [ 99%]
tests/test_testcases_exists.py::test_verify_parsed_and_reference_data_exists PASSED                                                            [100%]

================================================================ 428 passed in 43.84s ================================================================
______________________________________________________________________ summary _______________________________________________________________________
  py36: commands succeeded
  congratulations :)
$

Questions

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