ansible_facts showing interface eth0_1

[Kathy L]

I'm using ansible-core 1.18.  When I gather facts on a device, it shows the interfaces of eth0, eth0_1, eth1 and lo. The results of "ip a" show only eth0, eth1 and lo interfaces .  When I try to start arpwatch for each interface (other than lo), it fails on eth0_1, which makes sense to me.  Why does ansible_facts interfaces show eth0_1?

[SP1 -77]

Hi 👋 

It’s the VLAN ID for the sub-interface which ansible_facts is showing for eth0_1

You must use the iproute 2 package with ip addr not net-tools

If you want to modify this then you will need set_facts magic;

To access variables of other hosts, you should enable fact caching.

In playbook files, you should adding gather_facts: True to update facts.

The ansible_interfaces fact lists all of the existing network interfaces.

Some hints to get an interface when you know more information:

    var:
      allNetworkInterfaces: "{{ ansible_facts | dict2items | selectattr('value.ipv4', 'defined') | map(attribute='value') | list }}"
      allNetworkInterfaces_variant2: "{{ ansible_facts.interfaces | map('extract', ansible_facts ) | list }}"
      interfaceWithKnownIp: "{{ ansible_facts | dict2items | selectattr('value.ipv4', 'defined') | selectattr('value.ipv4.address', 'equalto', myKnowIpV4) | first }}"
      interfaceWithKnownIp_fromVar: "{{ allNetworkInterfaces | selectattr('ipv4.address', 'equalto', myKnowIpV4) | first }}"
      interfacesWithPartialKnowMac: "{{ allNetworkInterfaces | selectattr('macaddress', 'match', knownMacPrefix~'.*') | list }}"
      interfacesWitKnowType: "{{ allNetworkInterfaces | selectattr('type', 'equalto', knownType) | sort(attribute='device') | list }}"
      # extended on 2020-10-28
      queryForKnownIpv6: "[*].{device: device, ipv4: ipv4, ipv6: ipv6[? address == 'fe80::a00:27ff:fe38:ad36']}[?ipv6])" # string must be in ' # sorry, only partial interface info, did not find out how to return all info directly
      interfacesWithKnownIpv6: '{{ allNetworkInterfaces | json_query(queryForKnownIpv6) | first }}'
      queryForKnownIpv4_linux: "[?ipv4.address == '{{ myKnownIpV4 }}']}[?ipv4])" # string must be in '
      interfacesWithKnownIp_variantJsonQuery: '{{ allNetworkInterfaces | json_query(queryForKnownIpv4_linux) | first }}'

some short explications:

• dict2item because selectattrexpects an array
• map(attribute='...') to unpack this array
• map('extract', ...) to extract interfaces from ansible_facts
• ansible_facts.interfaces is the same as ansible_interfaces
• json_query() for flexible selecting and unpacking, an alternative variant with `map()? is welcome

the ansible_interfaces fact contains a list of all the network interfaces and they appear to be in order (i.e., the first ethernet interface would have been called eth0, the second eth1, etc). With a little set_fact magic:

- name: define traditional ethernet facts
  set_fact:
    ansible_eth: "{% set ansible_eth = ansible_eth|default([]) + [hostvars[inventory_hostname]['ansible_' + item]] %}{{ ansible_eth|list }}"
  when: hostvars[inventory_hostname]['ansible_' + item]['type'] == 'ether'
  with_items:
    - "{{ hostvars[inventory_hostname]['ansible_interfaces'] }}"

This loops over all of the ansible_interfaces entries for the current machine and builds a list of the hostvars[inventory_hostname]['ansible_' + item] entries that have a type equal to "ether".

Thus now ansible_eth.0 and ansible_eth.1 should be roughly equivalent to the old ansible_eth0 and ansible_eth1 respectively.

Best,

S.W

On Thu, 12 Jan 2023 at 11:24, Kathy L <lyon...@gmail.com> wrote:

I'm using ansible-core 1.18.  When I gather facts on a device, it shows the interfaces of eth0, eth0_1, eth1 and lo. The results of "ip a" show only eth0, eth1 and lo interfaces .  When I try to start arpwatch for each interface (other than lo), it fails on eth0_1, which makes sense to me.  Why does ansible_facts interfaces show eth0_1?

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[SP1 -77]

Hi 👋 

It’s the VLAN ID for the sub-interface which ansible_facts is showing for eth0_1

You must use the iproute 2 package with ip addr not net-tools

If you want to modify this then you will need set_facts magic;

To access variables of other hosts, you should enable fact caching.

In playbook files, you should add in:

gather_facts: True 

#to update facts.

The ansible_interfaces fact lists all of the existing network interfaces.

Some hints to get an interface when you know more information:

    var:

      allNetworkInterfaces: "{{ ansible_facts | dict2items | selectattr('value.ipv4', 'defined') | map(attribute='value') | list }}"

      allNetworkInterfaces_variant2: "{{ ansible_facts.interfaces | map('extract', ansible_facts ) | list }}"

      interfaceWithKnownIp: "{{ ansible_facts | dict2items | selectattr('value.ipv4', 'defined') | selectattr('value.ipv4.address', 'equalto', myKnowIpV4) | first }}"

      interfaceWithKnownIp_fromVar: "{{ allNetworkInterfaces | selectattr('ipv4.address', 'equalto', myKnowIpV4) | first }}"

      interfacesWithPartialKnowMac: "{{ allNetworkInterfaces | selectattr('macaddress', 'match', knownMacPrefix~'.*') | list }}"

      interfacesWitKnowType: "{{ allNetworkInterfaces | selectattr('type', 'equalto', knownType) | sort(attribute='device') | list }}"

      # extended on 2020-10-28

      queryForKnownIpv6: "[*].{device: device, ipv4: ipv4, ipv6: ipv6[? address == 'fe80::a00:27ff:fe38:ad36']}[?ipv6])" # string must be in ' # sorry, only partial interface info, did not find out how to return all info directly

      interfacesWithKnownIpv6: '{{ allNetworkInterfaces | json_query(queryForKnownIpv6) | first }}'

      queryForKnownIpv4_linux: "[?ipv4.address == '{{ myKnownIpV4 }}']}[?ipv4])" # string must be in '

      interfacesWithKnownIp_variantJsonQuery: '{{ allNetworkInterfaces | json_query(queryForKnownIpv4_linux) | first }}'

some short explications:

• dict2item because selectattr expects an array

• map(attribute='...') to unpack this array
• map('extract', ...) to extract interfaces from ansible_facts
• ansible_facts.interfaces is the same as ansible_interfaces
• json_query() for flexible selecting and unpacking, an alternative variant with `map()? is welcome

the ansible_interfaces fact contains a list of all the network interfaces and they appear to be in order (i.e., the first ethernet interface would have been called eth0, the second eth1, etc). With a little set_fact magic:

- name: define traditional ethernet facts

  set_fact:

    ansible_eth: "{% set ansible_eth = ansible_eth|default([]) + [hostvars[inventory_hostname]['ansible_' + item]] %}{{ ansible_eth|list }}"

  when: hostvars[inventory_hostname]['ansible_' + item]['type'] == 'ether'

  with_items:

    - "{{ hostvars[inventory_hostname]['ansible_interfaces'] }}"

This loops over all of the ansible_interfaces entries for the current machine and builds a list of the hostvars[inventory_hostname]['ansible_' + item] entries that have a type equal to "ether".

Thus now ansible_eth.0 and ansible_eth.1 should be roughly equivalent to the old ansible_eth0 and ansible_eth1 respectively.

Best,

S.W

On Thu, 12 Jan 2023 at 11:24, Kathy L <lyon...@gmail.com> wrote:

I'm using ansible-core 1.18.  When I gather facts on a device, it shows the interfaces of eth0, eth0_1, eth1 and lo. The results of "ip a" show only eth0, eth1 and lo interfaces .  When I try to start arpwatch for each interface (other than lo), it fails on eth0_1, which makes sense to me.  Why does ansible_facts interfaces show eth0_1?

--

[Kathy L]

Thanks for that info - very interesting.

I'm trying to start arpwatch for each interface using the following:

    name: Start arpwatch
    command: arpwatch -i {{ item }}
    loop:  "{{ ansible_interfaces }}"
    when:  ansible_facts[item] is defined and not 'lo'

I need to provide for eth interfaces as well as ens192... etc.  Any idea what I can do to ignore these VLAN interfaces?

[Todd Lewis]

Kathy, your "when:" condition is incorrect. "not 'lo'" will always be false, so likewise

  when: ansible_facts[item] is defined and not 'lo'

will also always be false.

To view this discussion on the web visit https://groups.google.com/d/msgid/ansible-project/78ec98fd-b8ea-4e8b-9ece-638ed08e96e3n%40googlegroups.com.

-- 
Todd

[Kathy L]

That makes sense -thank you. Sorry for the confusion - some of your text is white and did not display against my white background!  It works now!