Intent Driven OrchestrationDecember 12th, 2022 • Comments Off on Intent Driven Orchestration
So let’s start with a bolt statement: the introduction of Microservices/functions and Serverless deployment styles for cloud-native applications has triggered a need to shift the orchestration paradigms towards an intent-driven model.
So what are intents – and what does intent-driven mean? Imagine a restaurant and you order a medium rare steak – the “medium rare” part is the intent declaration. But if we contrast this concept to how orchestration stacks work today – you’d walk into the restaurant, walk straight into the kitchen and you’d say “put the burner on 80% and use that spatula” etc. Essentially declaratively asking for certain amounts of resources/certain way of setup. And obviously, there are a couple of issues with that – you do not necessarily know all the details of the burner. Should it have been set to 80% or 75% maybe? Should it have been 1 core, 500Mb or RAM, sth else? Abstractions and Serverless, anyone?
So why not let app/service owners define what they care about – the objectives of their app/service? For example, “I want P99 latency to be less than 20ms”. That is the “medium rare” intent declaration for an app/service. That is what we’ve been working on here at Intel – and now we’ve released our Intent-Driven Orchestration Planner (Github) for Kubernetes.
Btw.: I shamelessly stole the restaurant metaphor from Kelsey Hightower – for example, check out this podcast. On the P-numbers – again sth that other people have been writing about as well, see Tim Bray‘s blog post on Serverless (part of a Series).
Based on the intents defined by the service owner we want the orchestration stack to handle the rest – just like a good chef. We can do this through scheduling (where/when to place) and planning (how/what to do), to figure out how to set up the stack to make sure the objectives (SLOs) are met.
So why though a planner? The planning component brings sth to the table that the scheduler cannot. It continuously tries to match desired and current objectives of all the workloads. It does this based on data coming from the observability/monitoring stack and tries to reason to enable efficient management. In doing so it can trade-off between various motivations for the stakeholders at play and even take proactive actions if needed – the possibilities for a planner are huge. In the end, the planner can e.g. modify POD specs so the scheduler can make more informed decisions.
Here is an example of that an intent declaration for out Intent Driven Orchestration Planner can look like – essentially requesting that P99 latency should be below 20ms for a target Kubernetes Deployment:
apiVersion: "ido.intel.com/v1alpha1" kind: Intent metadata: name: my-function-intent spec: targetRef: kind: "Deployment" name: "default/function-deployment" objectives: - name: my-function-p99compliance value: 20 measuredBy: default/p99latency
Again the usage of planners is not revolutionary per se, NASA has even flown them to space – and could demonstrate some nice self-healing capabilities – on e.g. Deep Space 1. And just as Deep Space 1 was a tech demonstrator, maybe a quick note: this is all early days for intent-driven orchestration, but we would be very interested in learning what you think…
So ultimately, by better understanding the intents of the apps/services instead of just their desired declarative state, orchestrators – thanks to an intent-driven model – can make decisions that will lead to efficiency gains for service and resource owners.