kube-scheduler | A kubernetes utility to run docker images on a cron schedule | Cron Utils library

Posting this as community wiki, please feel free and provide more details and findings about this topic.

The only one place where we can find information about comma separated list of ports and port ranges is minikube documentation:

Increasing the NodePort range

By default, minikube only exposes ports 30000-32767. If this does not work for >you, you can adjust the range by using:

minikube start --extra-config=apiserver.service-node-port-range=1-65535

This flag also accepts a comma separated list of ports and port ranges.

On the other hand from the k8s documentation:

--service-node-port-range Default: 30000-32767

Error you included states that you are misising bridge-nf-call-iptables.
bridge-nf-call-iptables is exported by br_netfilter.
What you need to do is issue the command

Flannel does not support NFT, and since you are using CentOS 8, you can't fallback to iptables.
Your best bet in this situation would be to switch to Calico.
You have to update Calico DaemonSet with:

The reason for your issues is that the TLS connection between the components has to be secured. From the kubelet point of view this will be safe if the Api-server certificate will contain in alternative names the IP of the server that we want to connect to. You can notice yourself that you only add to SANs one IP address.

How can you fix this? There are two ways:

1. Use the --discovery-token-unsafe-skip-ca-verification flag with your kubeadm join command from your node.

2. Add the IP address from the second NIC to SANs api certificate at the cluster initialization phase (kubeadm init)

For more reading you check this directly related PR #93264 which was introduced in kubernetes 1.19.

Are you still having this error? I managed to fix this by downgrading windows kube-proxy to at least 1.20.0. There must be some missing config or bug for 1.21.0.

As already discussed in the comments the Ingress Controller will be created in the ingress-nginx namespace instead of the kube-system namespace. Other than that the rest of the tutorial should work as expected.

The answer is: it depends.

• You may have specified a different port for serving HTTP with --port flag
• You may have disabled serving HTTP altogether with --port 0
• You are using latest version of K8s

Last one is most probable as Creating a cluster with kubeadm states it is written for version 1.21

Ports 10251 and 10252 have been replaced in veresion 1.17 (see more here)

Kubeadm: enable the usage of the secure kube-scheduler and kube-controller-manager ports for health checks. For kube-scheduler was 10251, becomes 10259. For kube-controller-manager was 10252, becomes 10257.

Moreover, this functionality is depracted in 1.19 (more here)

Kube-apiserver: the componentstatus API is deprecated. This API provided status of etcd, kube-scheduler, and kube-controller-manager components, but only worked when those components were local to the API server, and when kube-scheduler and kube-controller-manager exposed unsecured health endpoints. Instead of this API, etcd health is included in the kube-apiserver health check and kube-scheduler/kube-controller-manager health checks can be made directly against those components' health endpoints.

It seems some parts of documentation are outdated.

This issue was solved recently. Here is more information: https://github.com/prometheus-community/helm-charts/issues/467 and here: https://github.com/prometheus-community/helm-charts/pull/757

Here is the solution (https://github.com/prometheus-community/helm-charts/issues/467#issuecomment-802642666):

[you need to] opt-out the rootfs host mount (preventing the crash). In order to do that you need to specify the following value in values.yaml file:

In this case, adding hostNetwork:true under spec.template.spec to the metrics-server Deployment may help.