I put up a draft AIP for scheduler-managed backfill here: https://cwiki.apache.org/confluence/display/AIRFLOW/AIP-78+Scheduler-managed+backfill
Quick summary: TLDR: move backfill from CLI process to the scheduler Backfill currently is a CLI-only feature that in effect runs a scheduler locally in the CLI process. We don't have good visibility of backfill jobs in the web UI, and users without CLI access cannot access the feature. Additionally, it's not ideal to have a "second scheduler" from a project maintenance perspective. This AIP focuses specifically on moving management of backfill jobs to the scheduler. This will take something away from users. Previously you could run backfill in local mode which would not only schedule the backfill locally but run all the tasks locally as well. This will go away. And the scheduler will of course have more to do, to the extent that backfill is used. The scheduler will become somewhat more complex since it will have to manage backfill runs too. There are some interactions with other AIPs. E.g. backfill is fundamentally about data completeness. And the data awareness AIPs may change what that can mean in Airflow. I look forward to your feedback. Thanks
