The update_function_configuration currently returns an empty dict no matter what but certain lambda libraries (ie, Zappa) require a realistic return value... which is simply the current config after being updated.

https://github.com/localstack/localstack/blob/9cba1010dfcbf2b7672df4d7da46b7e8ab287f64/localstack/services/awslambda/lambda_api.py#L872

https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/lambda.html#Lambda.Client.update_function_configuration

There might also be some other magic enriching that result but my quick read-through looks like it's an empty dict.



<!-- Love localstack? Please consider supporting our collective:
👉  https://opencollective.com/localstack/donate -->
}]
    }
    iam_client.create_policy(PolicyName=POLICY_NAME_PATTERN % function,
        PolicyDocument=json.dumps(policy), Description='Policy for Lambda function "%s"' % function)
    result = {'Statement': sid}
    return jsonify(result)
@app.route('%s/functions/<function>/policy/<statement>' % PATH_ROOT, methods=['DELETE'])
def remove_permission(function, statement):
    qualifier = request.args.get('Qualifier')
    iam_client = aws_stack.connect_to_service('iam')
    policy = get_lambda_policy(function)
    if not policy:
        return error_response('Unable to find policy for Lambda function "%s"' % function,
            404, error_type='ResourceNotFoundException')
    iam_client.delete_policy(PolicyArn=policy['PolicyArn'])
    result = {
        'FunctionName': function,
        'Qualifier': qualifier,
        'StatementId': policy['Statement'][0]['Sid'],
    }
    return jsonify(result)
@app.route('%s/functions/<function>/policy' % PATH_ROOT, methods=['GET'])
def get_policy(function):
    policy = get_lambda_policy(function)
    if not policy:
        return jsonify({}), 404
    return jsonify({'Policy': policy})
@app.route('%s/functions/<function>/invocations' % PATH_ROOT, methods=['POST'])
def invoke_function(function):
    """ Invoke an existing function