Locate string/integer not in list - ansible

Question

Im pulling a list of VLANs from our IPAM via an API and I want to be able to locate an unused "vlanId" that isnt in the list. I was expecting that I could use with_items for the JSON content and then use the random function with an until loop and occasionally it will initially generate a number that doesnt exist in the list. Mostly it just gets stuck and doesnt generate a new random number when the one generated already exists.
Playbook:
- uri:
url: "#"
validate_certs: no
headers:
token: "{{ token }}"
method: GET
force_basic_auth: yes
return_content: yes
register: ipam
- set_fact:
value: "{{ 4094 | random(start=1) }}"
until: value not in item.vlanId
with_items: "{{ ipam.json.data }}"
retries: 4093
- debug: msg="{{ value }}"
Relevant Output:
ok: [localhost] => (item={u'domainId': u'3', u'description': u'#', u'editDate': None, u'Customer ID': None, u'number': u'2241', u'vlanId': u'548', u'name': u'2241', u'Customer Name': None, u'custom_fields': None, u'Engineer': None}) => {
"ansible_facts": {
"value": "2727"
},
"ansible_facts_cacheable": false,
"attempts": 1,
"changed": false,
"item": {
"Customer ID": null,
"Customer Name": null,
"Engineer": null,
"custom_fields": null,
"description": "#",
"domainId": "3",
"editDate": null,
"name": "2241",
"number": "2241",
"vlanId": "548"
}
}
ok: [localhost] => (item={u'domainId': u'3', u'description': u'#', u'editDate': None, u'Customer ID': None, u'number': u'2242', u'vlanId': u'549', u'name': u'2242', u'Customer Name': None, u'custom_fields': None, u'Engineer': None}) => {
"ansible_facts": {
"value": "1955"
},
"ansible_facts_cacheable": false,
"attempts": 1,
"changed": false,
"item": {
"Customer ID": null,
"Customer Name": null,
"Engineer": null,
"custom_fields": null,
"description": "#",
"domainId": "3",
"editDate": null,
"name": "2242",
"number": "2242",
"vlanId": "549"
}
}
FAILED - RETRYING: set_fact (4000 retries left).Result was: {
"ansible_facts": {
"value": "50"
},
"ansible_facts_cacheable": false,
"attempts": 1,
"changed": false,
"retries": 4001
}
FAILED - RETRYING: set_fact (3999 retries left).Result was: {
"ansible_facts": {
"value": "50"
},
"ansible_facts_cacheable": false,
"attempts": 2,
"changed": false,
"retries": 4001
}
FAILED - RETRYING: set_fact (3998 retries left).Result was: {
"ansible_facts": {
"value": "50"
},
"ansible_facts_cacheable": false,
"attempts": 3,
"changed": false,
"retries": 4001
Im currently using ansible 2.4.2.0
If this is something that cant/shouldnt be done in Ansible, any guidance would be appreciated.

Answer 1

Here's what you want:
- debug:
msg: "{{ range(1, 4095) | difference(vlanIds) | random }}"
vars:
vlanIds: "{{ ipam.json.data | map(attribute='vlanId') | list }}"
Explanation:
map(attribute=... - create a list of vlan IDs,
range - generate a sequence from 1 to 4094,
difference - select all the elements from the above. that are not on the vlanIds list,
random - select a random element from the above.
For strings (as the title suggests) replace range with a list of possible strings.