This page explains GKE on Bare Metal release 1.8 quotas and limits for Google Cloud projects, clusters, and nodes.
Limits
Note the following limits and recommendations for your clusters.
Maximum number of pods per cluster
We recommend that you limit the number of pods per cluster to 15,000 or fewer. For example, if your cluster has 200 nodes, you should restrict the number of pods per node to 75 or fewer. Likewise, if you want to run 110 pods per node, you should restrict the number of nodes in your cluster to 136 or fewer. The following table provides examples of configurations that are and aren't recommended.
| Pods per node | Nodes per cluster | Pods per Cluster | Result |
|---|---|---|---|
| 110 | 200 | 22,000 | Too many pods, not recommended |
| 110 | 136 | 14,960 | Within limit |
| 100 | 150 | 15,000 | Within limit |
| 75 | 200 | 15,000 | Within limit |
The maximum number of pods per cluster recommendation takes precedence over the recommendations for pods per node and nodes per cluster in the following sections.
Maximum number of nodes per cluster
We test GKE on Bare Metal to run workloads with up to 500 nodes. However, to ensure optimal performance and reliability, we recommend that you don't exceed 200 nodes per cluster when running workloads in production.
| Cluster type | Minimum nodes | Recommended maximum nodes | Absolute maximum nodes |
|---|---|---|---|
| User, Standalone, or Hybrid | 1 | 200 | 500 |
For single-node clusters, you must remove the
node-role.kubernetes.io/master:NoSchedule taint to run workloads on the node.
For details, see
Kubernetes taints and tolerations.
Maximum number of pods per node
GKE on Bare Metal supports the configuration of maximum pods per node in
the nodeConfig.PodDensity.MaxPodsPerNode setting of the cluster configuration
file. The
following table shows the minimum and maximum values supported for
MaxPodsPerNode, which includes pods running add-on services:
| Cluster type | Minimum allowed value | Recommended maximum value | Maximum allowed value |
|---|---|---|---|
| All HA clusters and non-HA user clusters | 32 | 110 | 250 |
| All other non-HA clusters | 64 | 110 | 250 |
Maximum number of endpoints
On RHEL and CentOS, there's a cluster-level limitation of 100,000 endpoints.
This number is the sum of all pods that are referenced by a Kubernetes service.
If two services reference the same set of pods, this situation counts as two
separate sets of endpoints. The underlying nftable implementation on RHEL and
CentOS causes this limitation; it's not an intrinsic limitation of
GKE on Bare Metal.
Mitigation
For RHEL and CentOS, there are no mitigations. For Ubuntu and Debian
systems, we recommend
switching from the default iptables to legacy iptables
on large-scale clusters.
Dataplane V2 eBPF limit
The maximum number of entries in the BPF lbmap for Dataplane V2 is 65,536. Increases in the following areas can cause the total number of entries to grow:
- Number of services
- Number of ports per service
- Number of backends per service
We recommend that you monitor the actual number of entries used by your cluster to ensure that you don't exceed the limit. Use the following command to get the current entries:
kubectl get po -n kube-system -l k8s-app=cilium | cut -d " " -f1 | grep anetd | head -n1 | \
xargs -I % kubectl -n kube-system exec % -- cilium bpf lb list | wc -l
We also recommend that you use your own monitoring pipeline to collect metrics
from the anetd DaemonSet. Monitor for the following conditions to identify
when the number of entries are causing problems:
cilium_bpf_map_ops_total{map_name="lb4_services_v2",operation="update",outcome="fail" } > 0
cilium_bpf_map_ops_total{map_name="lb4_backends_v2",operation="update",outcome="fail" } > 0
LoadBalancer and NodePort Services port limit
The port limit for LoadBalancer and NodePort Services is 2,768. The default port range is 30000-32767. If you exceed the limit, you can't create new LoadBalancer or NodePort Services and you can't add new node ports for existing services.
Use the following command to check the number of ports currently allocated:
kubectl get svc -A | grep : | tr -s ' ' | cut -d ' ' -f6 | tr ',' '\n' | wc -l
Bundled load balancer node connection limits
The number of connections allowed for each node used for bundled load balancing (MetalLB) is 28,000. The default ephemeral port range for these connections is 32768-60999. If you exceed the connection limit, requests to the LoadBalancer Service might fail.
If you need to expose a load balancer service that is capable of handling a substantial number of connections (for Ingress, for example), we recommend that you consider an alternate load balancing method to avoid this limitation with MetalLB.
Cluster quotas
You can register a maximum of 15 clusters by default. To register more clusters in GKE Hub, you can submit a request to increase your quota in the Google Cloud console:
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