yml_replace.py

import string, yaml

def load_yaml(file_path: str, context: dict = None):
    def string_constructor(loader, node):
        t = string.Template(node.value)
        value = t.substitute(context)
        return value
    
    l = yaml.SafeLoader
    l.add_constructor('tag:yaml.org,2002:str', string_constructor)

    token_re = string.Template.pattern
    l.add_implicit_resolver('tag:yaml.org,2002:str', token_re, None)
    
    with open(file_path, 'r') as f:
        x = yaml.safe_load(f)
    
    return x

context = {'ENV': 'dev', 'SLA_HRS': 24}
yaml_with_context = load_yaml('./props.yml', context)