'Append a string to a List in Ansible
I'm trying to append a string to a list in ansible , so basically i'll be building a payload to delete few of the topology records in the F5 GTM network gear.
I was able to create one single list which includes all the output of the respective topology record. For the each line of the output i need to append with a string 'delete'.
- name: Lookup Topology Records
bigip_command:
user: admin
password: password
server: gtm.abc.com
commands: "list gtm topology | grep -i '{{ item }}'"
warn: no
validate_certs: no
register: topology_info
delegate_to: localhost
loop: "{{ gtm_pool }}"
- debug: var=topology_info
- name: Sanitize the Topology records of the Pool
set_fact:
clean_topology_info: "{{ clean_topology_info | default ([]) + item.stdout_lines }}"
loop: "{{ topology_info.results }}"
- debug: var=clean_topology_info
- name: Sanitized Topology Info
vars:
topology_item: "{{ item }}"
set_fact:
sanitized_topology_info: "{{ sanitized_topology_info | default ([]) + topology_item }}"
loop: "{{ clean_topology_info }}"
- name: Build payload to delete the Topology Record
set_fact:
topology_payload: "{{ topology_payload | default([]) + ['delete'] + item }}"
loop: "{{ clean_topology_info }}"
- debug: var=topology_payload
------------------------------------------------------------
Debug outputs(stdout_lines) as below :-
"gtm_pool": [
"test-poo1",
"test-pool2"
]
debug of "topology_info" :-
"stdout_lines": [
[
"gtm topology ldns: subnet 10.10.10.0/24 server: pool /Common/test-pool1 {",
"gtm topology ldns: subnet 10.8.22.0/24 server: pool /Common/test-pool1 {"
]
]
"stdout_lines": [
[
"gtm topology ldns: subnet 0.0.0.0/0 server: pool /Common/test-pool2 {"
]
debug of "clean_topology_info":-
"clean_topology_info": [
[
"gtm topology ldns: subnet 10.10.10.0/24 server: pool /Common/test-pool1 {",
"gtm topology ldns: subnet 10.8.22.0/24 server: pool /Common/test-pool1 {",
],
[
"gtm topology ldns: subnet 0.0.0.0/0 server: pool /Common/test-pool2 {",
]
]
debug of "sanitized_topology_info":-
"sanitized_topology_info": [
"gtm topology ldns: subnet 10.10.10.0/24 server: pool /Common/test-pool1 {",
"gtm topology ldns: subnet 10.8.22.0/24 server: pool /Common/test-pool1 {",
"gtm topology ldns: subnet 0.0.0.0/0 server: pool /Common/test-pool2 {"
]
debug of "topology_payload":-
"topology_payload": [
"delete",
"gtm topology ldns: subnet 10.10.10.0/24 server: pool /Common/test-pool1 {",
"gtm topology ldns: subnet 10.8.22.0/24 server: pool /Common/test-pool1 {",
"delete",
"gtm topology ldns: subnet 0.0.0.0/0 server: pool /Common/test-pool2 {"
]
Expected output of topology_payload should be like :-
Basically i need to append a string 'delete' infront of the each output.
"topology_payload": [
"delete gtm topology ldns: subnet 10.10.10.0/24 server: pool /Common/test-pool1 {",
"delete gtm topology ldns: subnet 10.8.22.0/24 server: pool /Common/test-pool1 {",
"delete gtm topology ldns: subnet 0.0.0.0/0 server: pool /Common/test-pool2 {"
]
Expected output of topology_payload should be like :-
Basically i need to append a string 'delete' infront of the each output.
topology_payload:
- "delete gtm topology ldns: subnet 10.10.10.0/24 server: pool /Common/test-pool1"
- "delete gtm topology ldns: subnet 10.8.22.0/24 server: pool /Common/test-pool1"
- "delete gtm topology ldns: subnet 0.0.0.0/0 server: pool /Common/test-pool2"
Solution 1:[1]
Q: "Prepend a string 'delete' in front of each item."
A: Is this what you're looking for?
- hosts: localhost
vars:
info: ['a', 'b', 'c']
tasks:
- set_fact:
payload: "{{ payload|default([]) + ['delete ' ~ item] }}"
loop: "{{ info }}"
- debug:
var: payload
gives (abridged)
payload:
- delete a
- delete b
- delete c
The same result can be achieved without iteration (credit @Romain DEQUIDT)
- hosts: localhost
vars:
info: ['a', 'b', 'c']
payload: "{{ ['delete']|product(info)|map('join', ' ')|list }}"
tasks:
- debug:
var: payload
Q: "Prepend a string 'delete' in front of each output that starts with 'gtm topology'."
A: Use the test search
- hosts: localhost
gather_facts: false
vars:
info: ['a', 'gtm topology', 'c']
tasks:
- set_fact:
payload: "{{ payload|default([]) + ['delete ' ~ item] }}"
loop: "{{ info }}"
when: item is search('^gtm topology')
- debug:
var: payload
gives (abridged)
payload:
- delete gtm topology
The same result can be achieved without iteration
- hosts: localhost
vars:
info: ['a', 'gtm topology', 'c']
info_gtm_topology: "{{ info|select('search', '^gtm topology') }}"
payload: "{{ ['delete']|product(info_gtm_topology)|map('join', ' ')|list }}"
tasks:
- debug:
var: payload
Q: "In addition to the conditions above, process the list till 'test-pool1' is found."
A: Use the test search also to find the index of the last item
hosts: localhost
vars:
info: ['a', 'gtm topology 1', 'c', 'test-pool1', 'gtm topology 2', 'd']
stop_regex: '.*pool1.*'
stop_items: "{{ info|select('search', stop_regex) }}"
stop_index: "{{ info.index(stop_items.0) }}"
tasks:
- set_fact:
payload: "{{ payload|default([]) + ['delete ' ~ item] }}"
loop: "{{ info[:stop_index|int] }}"
when: item is search('^gtm topology')
- debug:
var: payload
gives (abridged)
payload:
- delete gtm topology 1
The same result can be achieved without iteration
- hosts: localhost
vars:
info: ['a', 'gtm topology 1', 'c', 'test-pool1', 'gtm topology 2', 'd']
stop_regex: '.*pool1.*'
stop_items: "{{ info|select('search', stop_regex) }}"
stop_index: "{{ info.index(stop_items.0) }}"
info_gtm_topology: "{{ info[:stop_index|int]|select('search', '^gtm topology') }}"
payload: "{{ ['delete']|product(info_gtm_topology)|map('join', ' ')|list }}"
tasks:
- debug:
var: payload
As a side note, you can create custom filters. See filter_plugins
shell> cat filter_plugins/list_search.py
import re
def list_search(l, x):
r = re.compile(x)
return list(filter(r.match, l))
def list_index(l, x, *i):
if len(i) == 0:
return l.index(x) if x in l else -1
elif len(i) == 1:
return l.index(x, i[0]) if x in l[i[0]:] else -1
else:
return l.index(x, i[0], i[1]) if x in l[i[0]:i[1]] else -1
class FilterModule(object):
''' Ansible filters for operating on lists '''
def filters(self):
return {
'list_index': list_index,
'list_search': list_search,
}
The play below
- hosts: localhost
vars:
info: ['a', 'gtm topology 1', 'c', 'test-pool1', 'gtm topology 2', 'd']
stop_regex: '.*pool1.*'
stop_items: "{{ info|list_search(stop_regex) }}"
stop_index: "{{ info|list_index(stop_items.0) }}"
info_gtm_topology: "{{ info[:stop_index|int]|select('search', '^gtm topology') }}"
payload: "{{ ['delete']|product(info_gtm_topology)|map('join', ' ')|list }}"
tasks:
- debug:
var: payload
gives the same result
payload:
- delete gtm topology 1
Solution 2:[2]
You can use the product filter to prefix or suffix list of item:
---
- hosts: localhost
gather_facts: false
vars:
string: "prepend "
list: ["value1", "value2", "value3"]
tasks:
- name: "prefix"
set_fact:
prefix_list: "{{ ["prefix_"] | product(list) | map('join') }}"
- debug:
msg: "{{ prefix_list }}"
- name: "suffix"
set_fact:
suffix_list: "{{ list | product(["_suffix"]) | map('join') }}"
- debug:
msg: "{{ suffix_list }}"
Solution 3:[3]
You can use the map filter to apply a function to each element in a list. Combining it with regex_replace you can achieve your desired result:
---
- hosts: localhost
gather_facts: false
vars:
string: "prepend "
list: ["value1", "value2", "value3"]
tasks:
- name: "append string to each element in a list"
set_fact:
list: "{{ list | map('regex_replace', '(.*)', '{{ string }}\\1') | list }}"
- debug:
msg: "{{ list }}"
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow
| Solution | Source |
|---|---|
| Solution 1 | |
| Solution 2 | |
| Solution 3 |