I am installing a k8s cluster on CentOS 8 Hyper-V virtual machines. I used my router DHCP server to give them static IP addresses, but I have no DNS.
When I was ready to setup kubernetes I ran sudo kubeadm init
I received the following warnings
[WARNING Hostname]: hostname "k8s-master" could not be reached [WARNING Hostname]: hostname "k8s-master": lookup k8s-master on 192.168.0.1:53: no such host
Hoping this would not matter, and that I could be using the static IP adresses I continued setting up the k8s dashboard. No information is available in the dashboard, and probably due to the following errors in the metric server
E0914 19:22:32.513517 1 manager.go:111] unable to fully collect metrics: [unable to fully scrape metrics from source kubelet_summary:k8s- worker1: unable to fetch metrics from Kubelet k8s-worker1 (k8s-worker1): Get https://k8s-worker1:10250/stats/summary?only_cpu_and_memory=true: dial tcp: lookup k8s-worker1 on 10.96.0.10:53: no such host, unable to fully scrape metrics from source kubelet_summary:k8s-master: unable to fetch metrics from Kubelet k8s-master (k8s-master): Get https://k8s-master:10250/stats /summary?only_cpu_and_memory=true: dial tcp: lookup k8s-master on 10.96.0.10:53: no such host]
I decided to edit the /etc/hosts file and add these entries
192.168.0.151 k8s-master 192.168.0.161 k8s-worker1
This did not solve my problem. My virtual machines are able to ping each other by hostname, but nslookup doesn't work.
I don't know the mechanism that k8s uses to resolve hostnames, and what else I can do to let k8s work without an external dns. Any help is very much appreciated.
Note: I have 'fixed; my issue by adding the following arguments in the metrics-server deployment.
However I would still like to know if this can still be fixed using hostnames, and how the hostname resolution works in kubernetes.