It'll save time in the long run.

cursed_post.py

import sys
from typing import List


def convert_kv_to_aws(lines: List[str]):
    arr = []
    for txt in lines:
        parts = txt.split(':')
        if len(parts) < 2:
            continue

        k, v = map(str.strip, parts)
        yaml = \
f"""
- name: {k}
  value: {v}
"""
        yaml = yaml.lstrip()
        arr.append(yaml)

    return arr


if __name__ == '__main__':
    lines = sys.stdin.readlines()
    print("".join(convert_kv_to_aws(lines)))
    
    
"""
12:17 $ python aws_env.py
      AWS_S3_BASE_URL:        s3-eu-west-1.amazonaws.com
      TEST1:                  foo
      TEST2:                  bar
      
- name: AWS_S3_BASE_URL
  value:s3-eu-west-1.amazonaws.com
- name: TEST1
  value: foo
- name: TEST2
  value: bar
"""