Set a fact based on a fact name in a fact

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1

I have a situation where I am trying to dynamically get the MAC address on the first NIC in a new VM created by Ansible. I could assume the HW Interface will be “eth0”, but it would be better to figure it out at runtime.

Register variable “create_vm_results” is:

ok: [localhost] => {
“create_vm_results”: {
“ansible_facts”: {
“hw_eth0”: {
“addresstype”: “assigned”,
“ipaddresses”: null,
“label”: “Network adapter 1”,
“macaddress”: “MAC”,
“macaddress_dash”: “Dash-MAC”,
“summary”: “VM Network”
},
“hw_guest_full_name”: “Red Hat Enterprise Linux 6 (64-bit)”,
“hw_guest_id”: “rhel6_64Guest”,
“hw_interfaces”: [
“eth0”
],
“hw_memtotal_mb”: 2048,
“hw_name”: “NAME”,
“hw_power_status”: “POWERED ON”,
“hw_processor_count”: 1,
“hw_product_uuid”: “UUID”,
“module_hw”: true
},
“changed”: true,
“changes”: “Created VM NAME”
}
}

Now set facts based on this portion of my playbook:

  • name: VMWARE - Identify NIC of primary interface
    set_fact:
    nic: “{{ create_vm_results.ansible_facts.hw_interfaces[0] }}”

  • name: VMWARE - Show Created VM Primary NIC (DEBUG)
    debug: var=nic

  • name: VMWARE - Identify Adapter of primary interface
    set_fact:
    adptr: “create_vm_results.ansible_facts.hw_{{ nic }}.macaddress”

  • name: VMWARE - Show Created VM Primary Adapter (DEBUG)
    debug: var=adptr

  • name: VMWARE - Identify MAC Address of primary interface
    set_fact:
    mac: “{{ adptr }}”

  • name: VMWARE - Show Created VM Primary MAC (DEBUG)
    debug: var=mac

This produced this output:

TASK [vm_create : VMWARE - Identify NIC of primary interface] ******************
ok: [localhost]

TASK [vm_create : VMWARE - Show Created VM Primary NIC (DEBUG)] ****************
ok: [localhost] => {
“nic”: “eth0”
}

TASK [vm_create : VMWARE - Identify Adapter of primary interface] **************
ok: [localhost]

TASK [vm_create : VMWARE - Show Created VM Primary Adapter (DEBUG)] ************
ok: [localhost] => {
“adptr”: “create_vm_results.ansible_facts.hw_eth0.macaddress”
}

TASK [vm_create : VMWARE - Identify MAC Address of primary interface] **********
ok: [localhost] => (item=create_vm_results.ansible_facts.hw_eth0.macaddress)

TASK [vm_create : VMWARE - Show Created VM Primary MAC (DEBUG)] ****************
ok: [localhost] => {
“mac”: “create_vm_results.ansible_facts.hw_eth0.macaddress”
}

The objective was to get the MAC, but instead it is the “fact” name. Is there a way to look up the value of this fact?

Any assistance would be appreciated.

Thanks

2

[snip]

- name: VMWARE - Identify Adapter of primary interface
  set_fact:
    adptr: "create_vm_results.ansible_facts.hw_{{ nic }}.macaddress"

- name: VMWARE - Show Created VM Primary Adapter (DEBUG)
  debug: var=adptr

[snip]

TASK [vm_create : VMWARE - Show Created VM Primary Adapter (DEBUG)]
************
ok: [localhost] => {
    "adptr": "create_vm_results.ansible_facts.hw_eth0.macaddress"
}

[snip]

The objective was to get the MAC, but instead it is the "fact" name. Is
there a way to look up the value of this fact?

Any assistance would be appreciated.

To use variables you need to use hostvars to make it work

{{ hostvars[inventory_hostname]['create_vm_results']['ansible_facts']['hw_' + nic]['macaddress'] }}

3

Thanks Kai!

That worked perfectly!

Lise