There are a couple ways to integrate SumoLogic with fluentd.
In both cases, in SumoLogic configure an HTTP collector to send the log data to. For the log messages to be grouped properly, make sure to not enable multiline processing or enable one message per request. This configuration will allow the fluentd plugin and the lamdba function mentioned below to send multiple JSON messages at a time (bulk update), with SumoLogic separating each JSON message into distinct SumoLogic messages for proper aggregation, etc.
One thing to note is I am assuming all the log messages are structured as JSON objects - haven't tested this out with unstructred text messages.