Parsing semi-structured text with Ansible
The cli_parse module parses semi-structured data such as network configurations into structured data to allow programmatic use of the data from that device. You can pull information from a network device and update a CMDB in one playbook. Use cases include automated troubleshooting, creating dynamic documentation, updating IPAM (IP address management) tools and so on.
Understanding the CLI parser
The ansible.netcommon collection version 1.2.0 or later includes the cli_parse module that can run CLI commands and parse the semi-structured text output. You can use the cli_parse module on a device, host, or platform that only supports a command-line interface and the commands issued return semi-structured text. The cli_parse module can either run a CLI command on a device and return a parsed result or can simply parse any text document. The cli_parse module includes cli_parser plugins to interface with a variety of parsing engines.
Why parse the text?
Parsing semi-structured data such as network configurations into structured data allows programmatic use of the data from that device. Use cases include automated troubleshooting, creating dynamic documentation, updating IPAM (IP address management) tools and so on. You may prefer to do this with Ansible natively to take advantage of native Ansible constructs such as:
- The when clause to conditionally run other tasks or roles
- The assert module to check configuration and operational state compliance
- The template module to generate reports about configuration and operational state information
- Templates and command or config modules to generate host, device, or platform commands or configuration
- The current platform facts modules to supplement native facts information
By parsing semi-structured text into Ansible native data structures, you can take full advantage of Ansible's network modules and plugins.
When not to parse the text
You should not parse semi-structured text when:
- The device, host, or platform has a RESTAPI and returns JSON.
- Existing Ansible facts modules already return the desired data.
- Ansible network resource modules exist for configuration management of the device and resource.
Parsing the CLI
The cli_parse module includes the following cli_parsing plugins:
- native
The native parsing engine built into Ansible and requires no addition python libraries
- xml
Convert XML to an Ansible native data structure
- textfsm
A python module which implements a template based state machine for parsing semi-formatted text
- ntc_templates
Predefined textfsm templates packages supporting a variety of platforms and commands
- ttp
A library for semi-structured text parsing using templates, with added capabilities to simplify the process
- pyats
Uses the parsers included with the Cisco Test Automation & Validation Solution
- json
Converts JSON output at the CLI to an Ansible native data structure
Although Ansible contains a number of plugins that can convert XML to Ansible native data structures, the``cli_parse`` module runs the command on devices that return XML and returns the converted data in a single task.
Because cli_parse uses a plugin based architecture, it can use additional parsing engines from any Ansible collection.
The ansible.netcommon.native and ansible.netcommon.json parsing engines are fully supported with a Red Hat Ansible Automation Platform subscription. Red Hat Ansible Automation Platform subscription support is limited to the use of the ntc_templates, pyATS, textfsm, xmltodict, public APIs as documented.
Parsing with the native parsing engine
The native parsing engine is included with the cli_parse module. It uses data captured using regular expressions to populate the parsed data structure. The native parsing engine requires a YAML template file to parse the command output.
Networking example
This example uses the output of a network device command and applies a native template to produce an output in Ansible structured data format.
The show interface command output from the network device looks as follows:
Ethernet1/1 is up admin state is up, Dedicated Interface Hardware: 100/1000/10000 Ethernet, address: 5254.005a.f8bd (bia 5254.005a.f8bd) MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, medium is broadcast Port mode is access full-duplex, auto-speed Beacon is turned off Auto-Negotiation is turned on FEC mode is Auto Input flow-control is off, output flow-control is off Auto-mdix is turned off Switchport monitor is off EtherType is 0x8100 EEE (efficient-ethernet) : n/a Last link flapped 4week(s) 6day(s) Last clearing of "show interface" counters never <...>Create the native template to match this output and store it as templates/nxos_show_interface.yaml:
--- - example: Ethernet1/1 is up getval: '(?P<name>\S+) is (?P<oper_state>\S+)' result: "{{ name }}": name: "{{ name }}" state: operating: "{{ oper_state }}" shared: true - example: admin state is up, Dedicated Interface getval: 'admin state is (?P<admin_state>\S+),' result: "{{ name }}": name: "{{ name }}" state: admin: "{{ admin_state }}" - example: " Hardware: Ethernet, address: 5254.005a.f8b5 (bia 5254.005a.f8b5)" getval: '\s+Hardware: (?P<hardware>.*), address: (?P<mac>\S+)' result: "{{ name }}": hardware: "{{ hardware }}" mac_address: "{{ mac }}"This native parser template is structured as a list of parsers, each containing the following key-value pairs:
- example - An example line of the text line to be parsed
- getval - A regular expression using named capture groups to store the extracted data
- result - A data tree, populated as a template, from the parsed data
- shared - (optional) The shared key makes the parsed values available to the rest of the parser entries until matched again.
The following example task uses cli_parse with the native parser and the example template above to parse the show interface command from a Cisco NXOS device:
- name: "Run command and parse with native" ansible.netcommon.cli_parse: command: show interface parser: name: ansible.netcommon.native set_fact: interfacesTaking a deeper dive into this task:
- The command option provides the command you want to run on the device or host. Alternately, you can provide text from a previous command with the text option instead.
- The parser option provides information specific to the parser engine.
- The name suboption provides the fully qualified collection name (FQCN) of the parsing engine (ansible.netcommon.native).
- The cli_parse module, by default, looks for the template in the templates directory as {{ short_os }}_{{ command }}.yaml.
- The short_os in the template filename is derived from either the host ansible_network_os or ansible_distribution.
- Spaces in the network or host command are replace with _ in the command portion of the template filename. In this example, the show interfaces network CLI command becomes show_interfaces in the filename.
ansible.netcommon.native parsing engine is fully supported with a Red Hat Ansible Automation Platform subscription.
Lastly in this task, the set_fact option sets the following interfaces fact for the device based on the now-structured data returned from cli_parse:
Ethernet1/1: hardware: 100/1000/10000 Ethernet mac_address: 5254.005a.f8bd name: Ethernet1/1 state: admin: up operating: up Ethernet1/10: hardware: 100/1000/10000 Ethernet mac_address: 5254.005a.f8c6 <...>
Linux example
You can also use the native parser to run commands and parse output from Linux hosts.
The output of a sample Linux command (ip addr show) looks as follows:
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: enp0s31f6: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_codel state DOWN group default qlen 1000 link/ether x2:6a:64:9d:84:19 brd ff:ff:ff:ff:ff:ff 3: wlp2s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000 link/ether x6:c2:44:f7:41:e0 brd ff:ff:ff:ff:ff:ff permaddr d8:f2:ca:99:5c:82Create the native template to match this output and store it as templates/fedora_ip_addr_show.yaml:
--- - example: '1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000' getval: | (?x) # free-spacing \d+:\s # the interface index (?P<name>\S+):\s # the name <(?P<properties>\S+)> # the properties \smtu\s(?P<mtu>\d+) # the mtu .* # gunk state\s(?P<state>\S+) # the state of the interface result: "{{ name }}": name: "{{ name }}" loopback: "{{ 'LOOPBACK' in stats.split(',') }}" up: "{{ 'UP' in properties.split(',') }}" carrier: "{{ not 'NO-CARRIER' in properties.split(',') }}" broadcast: "{{ 'BROADCAST' in properties.split(',') }}" multicast: "{{ 'MULTICAST' in properties.split(',') }}" state: "{{ state|lower() }}" mtu: "{{ mtu }}" shared: True - example: 'inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0' getval: | (?x) # free-spacing \s+inet\s(?P<inet>([0-9]{1,3}\.){3}[0-9]{1,3}) # the ip address /(?P<bits>\d{1,2}) # the mask bits result: "{{ name }}": ip_address: "{{ inet }}" mask_bits: "{{ bits }}"
The shared key in the parser template allows the interface name to be used in subsequent parser entries. The use of examples and free-spacing mode with the regular expressions makes the template easier to read.
The following example task uses cli_parse with the native parser and the example template above to parse the Linux output:
- name: Run command and parse ansible.netcommon.cli_parse: command: ip addr show parser: name: ansible.netcommon.native set_fact: interfacesThis task assumes you previously gathered facts to determine the ansible_distribution needed to locate the template. Alternately, you could provide the path in the parser/template_path option.
Lastly in this task, the set_fact option sets the following interfaces fact for the host, based on the now-structured data returned from cli_parse:
lo: broadcast: false carrier: true ip_address: 127.0.0.1 mask_bits: 8 mtu: 65536 multicast: false name: lo state: unknown up: true enp64s0u1: broadcast: true carrier: true ip_address: 192.168.86.83 mask_bits: 24 mtu: 1500 multicast: true name: enp64s0u1 state: up up: true <...>
Parsing JSON
Although Ansible will natively convert serialized JSON to Ansible native data when recognized, you can also use the cli_parse module for this conversion.
Example task:
- name: "Run command and parse as json" ansible.netcommon.cli_parse: command: show interface | json parser: name: ansible.netcommon.json register: interfacesTaking a deeper dive into this task:
- The show interface | json command is issued on the device.
- The output is set as the interfaces fact for the device.
- JSON support is provided primarily for playbook consistency.
The use of ansible.netcommon.json is fully supported with a Red Hat Ansible Automation Platform subscription
Parsing with ntc_templates
The ntc_templates python library includes pre-defined textfsm templates for parsing a variety of network device commands output.
Example task:
- name: "Run command and parse with ntc_templates" ansible.netcommon.cli_parse: command: show interface parser: name: ansible.netcommon.ntc_templates set_fact: interfacesTaking a deeper dive into this task:
- The ansible_network_os of the device is converted to the ntc_template format cisco_nxos. Alternately, you can provide the os with the parser/os option instead.
- The cisco_nxos_show_interface.textfsm template, included with the ntc_templates package, parses the output.
- See the ntc_templates README for additional information about the ntc_templates python library.
Red Hat Ansible Automation Platform subscription support is limited to the use of the ntc_templates public APIs as documented.
This task and and the predefined template sets the following fact as the interfaces fact for the host:
interfaces: - address: 5254.005a.f8b5 admin_state: up bandwidth: 1000000 Kbit bia: 5254.005a.f8b5 delay: 10 usec description: '' duplex: full-duplex encapsulation: ARPA hardware_type: Ethernet input_errors: '' input_packets: '' interface: mgmt0 ip_address: 192.168.101.14/24 last_link_flapped: '' link_status: up mode: '' mtu: '1500' output_errors: '' output_packets: '' speed: 1000 Mb/s - address: 5254.005a.f8bd admin_state: up bandwidth: 1000000 Kbit bia: 5254.005a.f8bd delay: 10 usec
Parsing with pyATS
pyATS is part of the Cisco Test Automation & Validation Solution. It includes many predefined parsers for a number of network platforms and commands. You can use the predefined parsers that are part of the pyATS package with the cli_parse module.
Example task:
- name: "Run command and parse with pyats" ansible.netcommon.cli_parse: command: show interface parser: name: ansible.netcommon.pyats set_fact: interfacesTaking a deeper dive into this task:
- The cli_parse modules converts the ansible_network_os automatically (in this example, ansible_network_os set to cisco.nxos.nxos, converts to nxos for pyATS. Alternately, you can set the OS with the parser/os option instead.
- Using a combination of the command and OS, the pyATS selects the following parser: https://pubhub.devnetcloud.com/media/genie-feature-browser/docs/#/parsers/show%2520interface.
- The cli_parse module sets cisco.ios.ios to iosxe for pyATS. You can override this with the parser/os option.
- cli_parse only uses the predefined parsers in pyATS. See the pyATS documentation and the full list of pyATS included parsers.
Red Hat Ansible Automation Platform subscription support is limited to the use of the pyATS public APIs as documented.
This task sets the following fact as the interfaces fact for the host:
mgmt0: admin_state: up auto_mdix: 'off' auto_negotiate: true bandwidth: 1000000 counters: in_broadcast_pkts: 3 in_multicast_pkts: 1652395 in_octets: 556155103 in_pkts: 2236713 in_unicast_pkts: 584259 rate: in_rate: 320 in_rate_pkts: 0 load_interval: 1 out_rate: 48 out_rate_pkts: 0 rx: true tx: true delay: 10 duplex_mode: full enabled: true encapsulations: encapsulation: arpa ethertype: '0x0000' ipv4: 192.168.101.14/24: ip: 192.168.101.14 prefix_length: '24' link_state: up <...>
Parsing with textfsm
textfsm is a Python module which implements a template-based state machine for parsing semi-formatted text.
The following sample``textfsm`` template is stored as templates/nxos_show_interface.textfsm
Value Required INTERFACE (\S+) Value LINK_STATUS (.+?) Value ADMIN_STATE (.+?) Value HARDWARE_TYPE (.\*) Value ADDRESS ([a-zA-Z0-9]+.[a-zA-Z0-9]+.[a-zA-Z0-9]+) Value BIA ([a-zA-Z0-9]+.[a-zA-Z0-9]+.[a-zA-Z0-9]+) Value DESCRIPTION (.\*) Value IP_ADDRESS (\d+\.\d+\.\d+\.\d+\/\d+) Value MTU (\d+) Value MODE (\S+) Value DUPLEX (.+duplex?) Value SPEED (.+?) Value INPUT_PACKETS (\d+) Value OUTPUT_PACKETS (\d+) Value INPUT_ERRORS (\d+) Value OUTPUT_ERRORS (\d+) Value BANDWIDTH (\d+\s+\w+) Value DELAY (\d+\s+\w+) Value ENCAPSULATION (\w+) Value LAST_LINK_FLAPPED (.+?) Start ^\S+\s+is.+ -> Continue.Record ^${INTERFACE}\s+is\s+${LINK_STATUS},\sline\sprotocol\sis\s${ADMIN_STATE}$$ ^${INTERFACE}\s+is\s+${LINK_STATUS}$$ ^admin\s+state\s+is\s+${ADMIN_STATE}, ^\s+Hardware(:|\s+is)\s+${HARDWARE_TYPE},\s+address(:|\s+is)\s+${ADDRESS}(.*bia\s+${BIA})* ^\s+Description:\s+${DESCRIPTION} ^\s+Internet\s+Address\s+is\s+${IP_ADDRESS} ^\s+Port\s+mode\s+is\s+${MODE} ^\s+${DUPLEX}, ${SPEED}(,|$$) ^\s+MTU\s+${MTU}.\*BW\s+${BANDWIDTH}.\*DLY\s+${DELAY} ^\s+Encapsulation\s+${ENCAPSULATION} ^\s+${INPUT_PACKETS}\s+input\s+packets\s+\d+\s+bytes\s\*$$ ^\s+${INPUT_ERRORS}\s+input\s+error\s+\d+\s+short\s+frame\s+\d+\s+overrun\s+\d+\s+underrun\s+\d+\s+ignored\s\*$$ ^\s+${OUTPUT_PACKETS}\s+output\s+packets\s+\d+\s+bytes\s\*$$ ^\s+${OUTPUT_ERRORS}\s+output\s+error\s+\d+\s+collision\s+\d+\s+deferred\s+\d+\s+late\s+collision\s\*$$ ^\s+Last\s+link\s+flapped\s+${LAST_LINK_FLAPPED}\s\*$$The following task uses the example template for textfsm with the cli_parse module.
- name: "Run command and parse with textfsm" ansible.netcommon.cli_parse: command: show interface parser: name: ansible.netcommon.textfsm set_fact: interfacesTaking a deeper dive into this task:
- The ansible_network_os for the device (cisco.nxos.nxos) is converted to nxos. Alternately you can provide the OS in the parser/os option instead.
- The textfsm template name defaulted to templates/nxos_show_interface.textfsm using a combination of the OS and command run. Alternately you can override the generated template path with the parser/template_path option.
- See the textfsm README for details.
- textfsm was previously made available as a filter plugin. Ansible users should transition to the cli_parse module.
Red Hat Ansible Automation Platform subscription support is limited to the use of the textfsm public APIs as documented.
This task sets the following fact as the interfaces fact for the host:
- ADDRESS: X254.005a.f8b5 ADMIN_STATE: up BANDWIDTH: 1000000 Kbit BIA: X254.005a.f8b5 DELAY: 10 usec DESCRIPTION: '' DUPLEX: full-duplex ENCAPSULATION: ARPA HARDWARE_TYPE: Ethernet INPUT_ERRORS: '' INPUT_PACKETS: '' INTERFACE: mgmt0 IP_ADDRESS: 192.168.101.14/24 LAST_LINK_FLAPPED: '' LINK_STATUS: up MODE: '' MTU: '1500' OUTPUT_ERRORS: '' OUTPUT_PACKETS: '' SPEED: 1000 Mb/s - ADDRESS: X254.005a.f8bd ADMIN_STATE: up BANDWIDTH: 1000000 Kbit BIA: X254.005a.f8bd
Parsing with TTP
TTP is a Python library for semi-structured text parsing using templates. TTP uses a jinja-like syntax to limit the need for regular expressions. Users familiar with jinja templating may find the TTP template syntax familiar.
The following is an example TTP template stored as templates/nxos_show_interfaces.ttp:
{{ interface }} is {{ state }}admin state is {{ admin_state }}{{ ignore(".\*") }}The following task uses this template to parse the show interface command output:
- name: "Run command and parse with ttp" ansible.netcommon.cli_parse: command: show interface parser: name: ansible.netcommon.ttp set_fact: interfacesTaking a deeper dive in this task:
- The default template path templates/nxos_show_interface.ttp was generated using the ansible_network_os for the host and command provided.
- TTP supports several additional variables that will be passed to the parser. These include:
- parser/vars/ttp_init - Additional parameter passed when the parser is initialized.
- parser/vars/ttp_results - Additional parameters used to influence the parser output.
- parser/vars/ttp_vars - Additional variables made available in the template.
- See the TTP documentation for details.
The task sets the follow fact as the interfaces fact for the host:
- admin_state: up, interface: mgmt0 state: up - admin_state: up, interface: Ethernet1/1 state: up - admin_state: up, interface: Ethernet1/2 state: up
Converting XML
Although Ansible contains a number of plugins that can convert XML to Ansible native data structures, the``cli_parse`` module runs the command on devices that return XML and returns the converted data in a single task.
This example task runs the show interface command and parses the output as XML:
- name: "Run command and parse as xml" ansible.netcommon.cli_parse: command: show interface | xml parser: name: ansible.netcommon.xml set_fact: interfaces
Red Hat Ansible Automation Platform subscription support is limited to the use of the xmltodict public APIs as documented.
This task sets the interfaces fact for the host based on this returned output:
nf:rpc-reply: '@xmlns': http://www.cisco.com/nxos:1.0:if_manager '@xmlns:nf': urn:ietf:params:xml:ns:netconf:base:1.0 nf:data: show: interface: __XML__OPT_Cmd_show_interface_quick: __XML__OPT_Cmd_show_interface___readonly__: __readonly__: TABLE_interface: ROW_interface: - admin_state: up encapsulation: ARPA eth_autoneg: 'on' eth_bia_addr: x254.005a.f8b5 eth_bw: '1000000'
Advanced use cases
The cli_parse module supports several features to support more complex uses cases.
Provide a full template path
Use the template_path option to override the default template path in the task:
- name: "Run command and parse with native" ansible.netcommon.cli_parse: command: show interface parser: name: ansible.netcommon.native template_path: /home/user/templates/filename.yaml
Provide command to parser different than the command run
Use the command suboption for the parser to configure the command the parser expects if it is different from the command cli_parse runs:
- name: "Run command and parse with native" ansible.netcommon.cli_parse: command: sho int parser: name: ansible.netcommon.native command: show interface
Provide a custom OS value
Use the os suboption to the parser to directly set the OS instead of using ansible_network_os or ansible_distribution to generate the template path or with the specified parser engine:
- name: Use ios instead of iosxe for pyats ansible.netcommon.cli_parse: command: show something parser: name: ansible.netcommon.pyats os: ios - name: Use linux instead of fedora from ansible_distribution ansible.netcommon.cli_parse: command: ps -ef parser: name: ansible.netcommon.native os: linux
Parse existing text
Use the text option instead of command to parse text collected earlier in the playbook.
# using /home/user/templates/filename.yaml - name: "Parse text from previous task" ansible.netcommon.cli_parse: text: "{{ output['stdout'] }}" parser: name: ansible.netcommon.native template_path: /home/user/templates/filename.yaml # using /home/user/templates/filename.yaml - name: "Parse text from file" ansible.netcommon.cli_parse: text: "{{ lookup('file', 'path/to/file.txt') }}" parser: name: ansible.netcommon.native template_path: /home/user/templates/filename.yaml # using templates/nxos_show_version.yaml - name: "Parse text from previous task" ansible.netcommon.cli_parse: text: "{{ sho_version['stdout'] }}" parser: name: ansible.netcommon.native os: nxos command: show version
See also
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