Cloud Custodian policy to stop EC2 instances containing a tag and not containing a tag value

Question

I want to stop EC2 instances which do not have a tag ABC and whose tag(ABC) value is not of type @gmail.com

I am trying to use the cloud custodian policy in AWS, I have written like this

  filters:
    - or:
      - "tag:ABC": absent
      - type: value
        key: "tag:ABC"
        op: ne
        value: '/^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@gmail.com/'
  actions:
    - stop

However, this code does not have the desired effect. Any idea why?

Answer 1

Created this policy using special filters example.

ec2-without-gmail-in-tag.yml

policies:
  - name: ec2-without-gmail-in-tag
    description: |
      Stop EC2 instances that do not have a tag or if the tag exists but doesnt have a specific value
    resource: ec2
    filters:
      - or:
        # check if tag is absent
        - "tag:ABC": absent
        # or check if tag does not contain @gmail.com using a negative lookahead
        - type: value
          key: "tag:ABC"
          op: regex
          value: '^((?!@gmail.com).)*$'

You can test out this filter using python's re module.

$ python

>>> import re

>>> regex = '^((?!@gmail.com).)*$'

>>> re.match(regex, 'Test if @gmail.com matches').group(0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'NoneType' object has no attribute 'group'

>>> re.match(regex, 'Test if @gmail matches').group(0)
'Test if @gmail matches'