By default Flink S3 sink writes in EXACTLY_ONCE delivery mode. I want to update it to AT_LEAST_ONCE mode. I am not able to find out that what configuration need to updated to make it happen.
From our job end, we are setting checkpoint config exactly_once. I am not sure if I update this checkpoint config to at_least once, it will also update the delivery mode config?
env.getCheckpointConfig().setCheckpointingMode(CheckpointingMode.EXACTLY_ONCE);
I'm confident that if you are using the (newer) FileSink to write to S3, all you need to do is change the checkpoint mode to be AT_LEAST_ONCE.
I'm not sure if there are any S3-specific configs for the older Flink file sink, but I think not, so even in that case you should be fine with just changing the checkpoint mode.