Ansible: json element strip key with colon - json

Question

How do you remove a json Key that contains a colon (:) with jinja2 rejectattr.
Environment:
ansible 2.9.1
config file = None
configured module search path = [u'/home/<user>/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
ansible python module location = /usr/lib/python2.7/dist-packages/ansible
executable location = /usr/bin/ansible
python version = 2.7.15+ (default, Oct 7 2019, 17:39:04) [GCC 7.4.0]
json data:
{
"tag:environment": "qa",
"tag:instance_id": "i-123456789"
}
Ansible playbook:
- name: Remove InstanceID
debug:
msg: "{{ instance_filter | rejectattr('['tag:environment'], 'defined' ') | list }}
Actual Results:
fatal: [localhost]: FAILED! => {
"msg": "template error while templating string: expected token ',', got 'tag'. String: {{ instance_filter | rejectattr('['tag:environment'], 'defined' ') | list }}"
}
Expected results:
{
"tag:environment": "qa"
}

Answer 1

The rejectattr is indeed one of the key filters to use to achieve your goal, but a few more things are needed. Here is the correct sequence of filters to remove that particular key from the dictionary variable you have:
Playbook:
---
- hosts: localhost
gather_facts: false
vars:
instance_filter:
tag:environment: qa
tag:instance_id: i-123456789
tasks:
- name: print var
debug:
var: instance_filter
- name: manipulate the var
debug:
msg: "{{ instance_filter | dict2items | rejectattr('key', 'equalto', 'tag:instance_id') | list | items2dict }}"
Output:
PLAY [localhost] *******************************************************************************************************************************************************************************************************
TASK [print var] *******************************************************************************************************************************************************************************************************
ok: [localhost] => {
"instance_filter": {
"tag:environment": "qa",
"tag:instance_id": "i-123456789"
}
}
TASK [manipulate the var] **********************************************************************************************************************************************************************************************
ok: [localhost] => {
"msg": {
"tag:environment": "qa"
}
}
PLAY RECAP *************************************************************************************************************************************************************************************************************
localhost : ok=2 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
hope it helps.

Answer 2

Q: "How do you remove a JSON key?"
A: It's possible to create custom filter plugins. For example
$ cat filter_plugins/dict_utils.py
def dict_del_key(d, key):
del d[key]
return d
class FilterModule(object):
''' Ansible filters. Interface to Python dictionary methods.'''
def filters(self):
return {
'dict_del_key' : dict_del_key
}
The play below
- hosts: localhost
vars:
dict:
'tag:environment': 'qa'
'tag:instance_id': 'i-123456789'
tasks:
- debug:
msg: "{{ dict|dict_del_key('tag:instance_id') }}"
gives
msg:
tag:environment: qa
Notes:
See If you quote those config keys, they will become strings.
See the difference between 7.3.1. Double-Quoted Style and 7.3.2. Single-Quoted Style.
FWIW. See other filters available at GitHub.