Details
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New Feature
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Status: Open
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Major
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Resolution: Unresolved
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0.23.6
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None
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None
Description
Problem Summary
For the purpose of chargeback and better understanding of grid usage, we need to be able to associate applications with "projects", e.g. "pipeline X", "property Y". This would allow us to aggregate on this property, thereby helping us compute grid resource usage for the entire "project". Currently, for a given application, two things we know about it are the user that submitted it and the queue it was submitted to. Below, I'll explain why neither of these is adequate for enterprise-level chargeback and understanding resource allocation needs.
Why Not Users?
Its not individual users that are paying the bill – its projects. When one of our real users submits an application on a Hadoop grid, they're presumably not usually doing it for themselves. They're doing work for some project or team effort, so its that team or project that should be "charged" for all its users applications. Maintaining outside lists of associations between users and projects is error-prone because it is time-sensitive and requires continued ongoing maintenance. New users join organizations, users leave and users even change projects. Furthermore, users may split their time between multiple projects, making it ambiguous as to which of a user's projects a given application should be charged. Also, there can be headless users, which can be even more difficult to link to a project and can be shared between teams or projects.
Why Not Queues?
The purpose of queues is for scheduling. Overloading the queues concept to also mean who should be "charged" for an application can have a detrimental effect on the primary purpose of queues. It could be manageable in the case of a very small number of projects sharing a cluster, but doesn't scale to tens or hundreds of projects sharing a cluster. If a given cluster is shared between 50 projects, creating 50 separate queues will result in inefficient use of the cluster resources. Furthermore, a given project may desire more than one queue for different types or priorities of applications.
Proposed Solution
Rather than relying on external tools to infer through the user and/or queue who to "charge" for a given application, I propose a straightforward approach where that information be explicitly supplied when the application is submitted, just like we do with queues. Let's use a charge card analogy: when you buy something online, you don't just say who you are and how to ship it, you also specify how you're paying for it. Similarly, when submitting an application in YARN, you could explicitly specify to whom it's resource usage should be associated (a project, team, cost center, etc).
This new configuration parameter should default to being optional, so that organizations not interested in chargeback or project-level resource tracking can happily continue on as if it wasn't there. However, it should be configurable at the cluster-level such that, a given cluster to could elect to make it required, so that all applications would have an associated project. The value of this new parameter should be exposed via the Resource Manager UI and Resource Manager REST API, so that users and tools can make use of it for chargeback, utilization metrics, etc.
I'm undecided on what to name the new parameter, as I like the flexibility in the ways it could be used. It is essentially just an additional party other than user or queue that an application can be associated with, so its use is not just limited to a chargeback scenario. For example, an organization not interested in chargeback could still use this parameter to communicate useful information about a application (e.g. pipelineX.stageN) and aggregate like applications.
Enforcement
Couldn't users just specify this information as a prefix for their job names? Yes, but the missing piece this could provides is enforcement. Ideally, I'd like this parameter to work very much like how the queues work. Like already exists with queues, it'd be ideal if a given user couldn't just specify any old value for this parameter. It could be configurable such that a given user only has permission to submit applications for specific "projects". Submitting an application with this parameter being anything other than what the given user is allowed, would cause the application to be rejected in the same manner as if the user has specified an invalid queue.
Again, so as to have no effect on organizations not interested in this feature, this enforcement should be off by default, but configurable at the cluster level such that it could be turned on for clusters wanting to use it.