Sometimes, attempting to run lambdas will return this type of error:
```
{"Type": "Server", "message": "Error executing Lambda function arn:aws:lambda:ap-northeast-1:000000000000:function:service-stage-functionName: An error occurred (ResourceAlreadyExistsException) when calling the CreateLogGroup operation: The specified log group already exists Traceback (most recent call last):\n 
File \"/opt/code/localstack/localstack/services/awslambda/lambda_api.py\", line 338, in run_lambda\n 
event, context=context, version=version, asynchronous=asynchronous)\n 
File \"/opt/code/localstack/localstack/services/awslambda/lambda_executors.py\", line 81, in execute\n 
return do_execute()\n File \"/opt/code/localstack/localstack/services/awslambda/lambda_executors.py\", line 70, in do_execute\n self._store_logs(func_details, log_output, invocation_time)\n 
File \"/opt/code/localstack/localstack/services/awslambda/lambda_executors.py\", line 105, in _store_logs\n logs_client.create_log_group(logGroupName=log_group_name)\n 
File \"/opt/code/localstack/.venv/lib/python3.6/site-packages/botocore/client.py\", line 357, in _api_call\n 
return self._make_api_call(operation_name, kwargs)\n 
File \"/opt/code/localstack/.venv/lib/python3.6/site-packages/botocore/client.py\", line 661, in _make_api_call\n 
raise error_class(parsed_response, operation_name)\n
botocore.errorfactory.ResourceAlreadyExistsException: An error occurred (ResourceAlreadyExistsException) when calling the CreateLogGroup operation: The specified log group already exists\n", "__type": "InternalFailure"}
```
I am not yet sure if there are any particular settings that cause it, since it does not occur for certain deployments.

Will update if I can figure out the exact configuration.
""" Return the string to be used for running Docker commands. """
        return config.DOCKER_CMD
    def prepare_event(self, environment, event_body):
        """ Return the event as a stdin string. """
        
        environment['AWS_LAMBDA_EVENT_BODY'] = event_body
        return None
    def _execute(self, func_arn, func_details, event, context=None, version=None):
        lambda_cwd = func_details.cwd
        runtime = func_details.runtime
        handler = func_details.handler
        environment = func_details.envvars.copy()
        
        if config.USE_SSL:
            environment['USE_SSL'] = '1'
        
        if not event:
            LOG.warning('Empty event body specified for invocation of Lambda "%s"' % func_arn)
            event = {}
        event_body = json.dumps(json_safe(event))
        stdin = self.prepare_event(environment, event_body)
        docker_host = config.DOCKER_HOST_FROM_CONTAINER
        environment['HOSTNAME'] = docker_host
        environment['LOCALSTACK_HOSTNAME'] = docker_host