CODEWITHSUNDEEP
kubernetesazure-aks
Djoby
Djoby

Reputation: 752

K8s Node allocatable not taking in account pod resources

I am making some tests, and I believe I may be misunderstanding how "allocatable" work. I have 2 nodes running on Azure-AKS, both with Memory capacity of 65 Gi, and nothing but some basic daemon running on them. When describing these nodes, I have for both about 59 Gi memory "allocatable".

Then I start a new pod, with a resources request and limit of 30Gi on one of these node. In practice, the pod use just a couple of Mo. I would be expecting the "allocatable" to reduce to 29 Gi, but it stays at 59 Gi.

If I am doing a describe, the "allocated" section will correctly display what I actually requested.

Allocated resources:
  (Total limits may be over 100 percent, i.e., overcommitted.)
  Resource                       Requests       Limits
  --------                       --------       ------
   memory                         31190Mi (53%)  32170Mi (55%)
   ....

But not the allocatable:

Allocatable:
  attachable-volumes-azure-disk:  16
  cpu:                            7820m
  ephemeral-storage:              119716326407
  hugepages-1Gi:                  0
  hugepages-2Mi:                  0
  memory:                         59350320Ki
  pods:                           30

So, is allocatable supposed to take in account the requested resources of the pod ?

If yes, why is the value not decreasing here?

If no, how can I know what is the total amount of request/limit on one specific node (in a parsable format, such as json) ?

Upvotes: 0

Views: 1203

Answers (1)

gohm'c
gohm'c

Reputation: 15500

is allocatable supposed to take in account the requested resources of the pod ?

No. Allocatable is your underlying instance capacity minus all the reserved (eg. system-reserved, kube-reserved, eviction threshold).

...how can I know what is the total amount of request/limit on one specific node?

You can continue use kubectl describe node, or kubectl top node, or kubernetes dasboard and many other monitoring tools out there.

Upvotes: 1

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