AWS supports the following Ruby runtimes:

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Name | Identifier | SDK for Ruby | Operating system
-- | -- | -- | --
Ruby 2.7 | ruby2.7 | 3.0.1 | Amazon Linux 2
Ruby 2.5 | ruby2.5 | 3.0.1 | Amazon Linux

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Currently, `localstack/lambda` only contains the `ruby2.5` tag. Will the 2.7 runtime be supported in the (near) future?
import re
import os
import json
import time
import shutil
import unittest
import six
import base64
from io import BytesIO
from datetime import datetime
from botocore.exceptions import ClientError
from localstack import config
from localstack.utils import testutil
from localstack.constants import LOCALSTACK_MAVEN_VERSION, LOCALSTACK_ROOT_FOLDER, LAMBDA_TEST_ROLE
from localstack.utils.aws import aws_stack, aws_models
from localstack.utils.common import (
    unzip, new_tmp_dir, short_uid, load_file, to_str, mkdir, download, save_file,