lambda-tagger.py

import sys
import boto3

region = 'us-east-1'
target_tag = 'project'

client = boto3.client('lambda', region)

functions = client.list_functions().get('Functions', [])

for function in functions:
    tags = client.list_tags(Resource=function['FunctionArn']).get('Tags', [])
    if target_tag not in tags:
        print(f"Lambda {function['FunctionArn']} is missing tag {target_tag}")

        tag_value = None
        if 'aws-scheduler' in function['FunctionArn']:
            tag_value = 'serverless-scheduler'
        elif 'testing-mail' in function['FunctionArn']:
            tag_value = 'research'

        if tag_value is not None:
            client.tag_resource(Resource=function['FunctionArn'], Tags={target_tag: tag_value})