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Calculate a resonable value for the --kube-reserved flag #44
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Kubernetes uses --kube-reserved to calculate the alocatable resources avalible on a node. This code uses the calucations documented by GKE here : https://cloud.google.com/kubernetes-engine/docs/concepts/cluster-architecture to calculate appropriate values for these flags, for the current instance type.
mtpereira
reviewed
Sep 18, 2018
| func reservedMemory(instanceType *string) string { | ||
| memory := InstanceMemory[*instanceType] | ||
| reserved := 0.0 | ||
| for i := 0; i < memory; i++ { |
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I think these if-else statement would be easier to read on as switch cases, specially if we'd use explicit ranges instead of relying on the previous missed branch.
mtpereira
reviewed
Sep 18, 2018
pkg/node/node.go
Outdated
| reserved += 0.02 | ||
| } | ||
| } | ||
| if reserved == 0.0 { |
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Where does this value come from? Couldn't find it on the GKE docs.
mtpereira
reviewed
Sep 18, 2018
pkg/node/node.go
Outdated
| reserved = 960.0 | ||
| } | ||
| return fmt.Sprintf("%.0fMi", reserved) | ||
| } |
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I don't think we're taking this into consideration:
GKE reserves an additional 100 MiB memory on each node for kubelet eviction
mtpereira
reviewed
Sep 18, 2018
| @@ -15,13 +15,14 @@ ExecStart=/usr/bin/kubelet \ | |||
| --cni-bin-dir=/opt/cni/bin \ | |||
| --cni-conf-dir=/etc/cni/net.d \ | |||
| --container-runtime=docker \ | |||
| --eviction-hard=memory.available<100Mi,nodefs.available<10%,nodefs.inodesFree<5% \ | |||
mtpereira
reviewed
Sep 18, 2018
| @@ -1,2 +1,4 @@ | |||
| [Service] | |||
| {{- if and .Node.ReservedCPU .Node.ReservedMemory }} | |||
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So, if one of them is unavailable we're assuming the instance type is unknown and we won't configure any reservation. Cool! 😄 👍
mtpereira
approved these changes
Sep 18, 2018
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Kubernetes uses --kube-reserved to calculate the alocatable resources
avalible on a node.
This code uses the calucations documented by GKE
here : https://cloud.google.com/kubernetes-engine/docs/concepts/cluster-architecture
to calculate appropriate values for these flags, for the current instance type.