Slider community,
The YARN team is discussing in YARN-4692<https://issues.apache.org/jira/browse/YARN-4692> on how to add "first class services" directly to YARN. Some of the names in the discussion document should be familiar: that's because Slider is essentially the original long-lived application in YARN. With YARN-4692<https://issues.apache.org/jira/browse/YARN-4692>, it is apparent that the Apache Hadoop YARN community is working towards providing direct support for long-lived services. I think we need to look at that proposal and think "where and how does Slider relate to this". Apache Slider (incubating) has been in the business of creating and managing long-running services in YARN for a couple of years. Today it is being used in production YARN clusters across several companies (big and small). Several production-grade applications (data and non-data) are available as sample packages. A good number of them have been contributed by interested parties like Lucidworks contributing a Solr Slider Application Package and DataTorrent contributing a Kafka Slider Application Package. Slider has been pretty good at taking existing applications and turning them into long-lived services in YARN. YARN offers the core scheduling, execution and failure reporting functions; slider takes that and adds: advanced container placement (history; anti-affine, escalation policies), configuration, dynamic binding, monitoring, failure handling, and an API for clients. It's also driven a lot of the YARN-896<https://issues.apache.org/jira/browse/YARN-896> "long-lived services" development: long-lived failure resilience, the YARN registry, container-preservation over YARN restarts. Big chunks of that code actually came from the Slider team. This was always a goal of the work even in its Hoya predecessor: show that YARN can be used to host applications like HBase, and identify where it can be be improved. What does it mean for Slider if YARN starts doing this directly? Slider provides a lot of the basic functionalities for long-running services proposed in YARN-4692. It is a universal YARN app-master and lets application-owners focus on their application functionalities, while it handles the internals of orchestrating services on YARN. Which means: we have an opportunity here to contribute the core of slider into YARN itself, and, with it in YARN, use it as the basis for the full TODO-list of YARN-4692. The YARN team gets the stable codebase that's evolved over the past few years: something to deploy applications in a YARN cluster. What does Slider get? We'd get to be the foundation for long lived YARN services with the new work on top. Would this work? What's wrong with the idea? How do we do it if we want to go with it? I would like to call upon the community to weigh in their thoughts and opinions on this topic. -Gour
