container.training/slides/exercises/reqlim-details.md

Exercise — Requests and Limits

By default, if we don't specify resource requests, our workloads will run in BestEffort quality of service.

BestEffort is very bad for production workloads, because the scheduler has no idea of the actual resource requirements of our apps, and won't be able to make smart decisions about workload placement.

As a result, when the cluster gets overloaded, containers will be killed, pods will be evicted, and service disruptions will happen.

Let's solve this!

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Check current state

• Check allocations

  (i.e. which pods have requests and limits for CPU and memory)

• Then check utilization

  (i.e. actual resource usage)

• Possible tools: kubectl, plugins like view-allocations, Prometheus...

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Follow best practices

• We want to make sure that all workloads have requests

  (and perhaps limits, too!)

• Depending on the workload:

  • edit its YAML manifest

  • adjust its Helm values

  • add LimitRange in its Namespace

• Then check again to confirm that the job has been done properly!

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Be future-proof!

• We want to make sure that future workloads will have requests, too

• How can that be implemented?