This is a script helps to add propagateTags property to AWS ECS service by re-creating it.

recreate-service.py

'''
This is a script helps to add propagateTags property to AWS ECS service by re-creating it.

Before you run the script,
    Make sure you understand script
    Change tags, cluster and service
    It is recommented to set desired tasks to 0 to service

Requirements:

python 3.6+
boto3
PyYAML

USAGE: python3 recreate-service.py

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
'''

import boto3
import yaml
import logging
from pathlib import Path
import os

logging.basicConfig(
    level=logging.INFO,
    format= '[%(asctime)s] [%(pathname)s:%(lineno)d] %(levelname)s - %(message)s',
    datefmt='%H:%M:%S'
)

log = logging.getLogger(__name__)


client = boto3.client('ecs')

tags = {
    # Add tags here
    # {
    #     "key1": "value1",
    #     "key2": "value2",
    # }
}

def get_awsecs_service(cluster_name, service_name):
    response = client.describe_services(
        cluster=cluster_name,
        services=[
            service_name,
        ]
    )
    service = response['services'][0]
    keys_to_remove = [
        'events',
        'createdAt',
        'deployments',
        'createdBy',
        'pendingCount',
        'runningCount',
        'serviceArn',
        'status',
        'clusterArn',
        'roleArn',
    ]
    for key in keys_to_remove:
        del service[key]
    return service

def add_tags(service):
    service['propagateTags'] = 'SERVICE'
    tags_list = [{'key': key, 'value': value} for key, value in tags.items()]
    service['tags'] = tags_list
    return service

def delete_service(cluster_name, service):
    client.delete_service(
        cluster=cluster_name,
        service=service,
        force=True,
    )

def create_awsecs_service(cluster_name, service):
    service['cluster'] = cluster_name
    client.create_service(**service)

def save_to_file(file_name, content):
    # create directory if not exists
    directory_path = os.path.dirname(file_name)
    Path(directory_path).mkdir(parents=True, exist_ok=True)

    # store to file
    with open(file_name, 'w') as service_file:
        yaml.dump(content, stream=service_file)

def get_file_content(file_name):
    with open(file_name, 'r') as service_file:
        return yaml.load(service_file)

def wait_for_service_to_drain(cluster_name, service_name):
    waiter = client.get_waiter('services_inactive')
    waiter.wait(
        cluster=cluster_name,
        services=[
            service_name,
        ],
        WaiterConfig={
            'MaxAttempts': 40 # 10 minutes
        }
    )


def main(cluster_name, service_name):
    backup_file_name = f'services_backup/{cluster_name}/{service_name}.yml'

    log.info(f'Fetching service {service_name}')
    service = get_awsecs_service(cluster_name, service_name)
    log.info('Got service')

    log.info(f'Adding tags - {tags}')
    new_service = add_tags(service)
    log.info('Tags added')

    log.info(f'creating backup of service {service_name} in file')
    save_to_file(backup_file_name, new_service)
    log.info('Done storing')

    log.info(f'Deleting service {service_name}')
    delete_service(cluster_name, service_name)
    log.info('Service deleted')

    log.info(f'Waiting for service {service_name} to drain - max 10 mins')
    wait_for_service_to_drain(cluster_name, service_name)

    # new_service = get_file_content(file_name)

    log.info(f'creating service {service_name}')
    create_awsecs_service(cluster_name, new_service)

if __name__ == '__main__':
    cluster_name = '<cluster-name>'
    service_name = '<service-name>'
    main(cluster_name, service_name)