HCCM should work with FQDN Servernames and Private IPs as Node IPs

[tehnic-take3]

TL;DR

Hello,

first - i prefer to use FQDN servernames like "k8s-control-plane1.mydomain.com", but then i get error messages in the HCCM log like:

I0722 xx:xx:xx.xxxxxx       1 node_controller.go:425] Initializing node k8s-control-plane1 with cloud provider
I0722 xx:xx:xx.xxxxxx       1 node_controller.go:229] error syncing 'k8s-control-plane1': failed to get instance metadata for node k8s-control-plane1: hcloud/instancesv2.InstanceMetadata: failed to get instance metadata: no matching server found for node 'k8s-control-plane1': server not found, requeuing
E0722 xx:xx:xx.xxxxxx       1 node_controller.go:240] error syncing 'k8s-control-plane1': failed to get instance metadata for node k8s-control-plane1: hcloud/instancesv2.InstanceMetadata: failed to get instance metadata: no matching server found for node 'k8s-control-plane1': server not found, requeuing

I suggest to have a HCCM configuration item to use the FQDN of all nodes for cloud provider API.

Second - after changing servername to one without domain, i get error messages like:

I0722 xx:xx:xx.xxxxxx       1 node_controller.go:425] Initializing node k8s-control-plane1 with cloud provider
I0722 xx:xx:xx.xxxxxx       1 node_controller.go:229] error syncing 'k8s-control-plane1': failed to get node modifiers from cloud provider: provided node ip for node "k8s-control-plane1" is not valid: failed to get node address from cloud provider that matches ip: 10.x.x.x, requeuing
E0722 xx:xx:xx.xxxxxx       1 node_controller.go:240] error syncing 'k8s-control-plane1': failed to get node modifiers from cloud provider: provided node ip for node "k8s-control-plane1" is not valid: failed to get node address from cloud provider that matches ip: 10.x.x.x, requeuing

I used "KUBELET_EXTRA_ARGS=--cloud-provider=external --node-ip=10.x.x.x" for kubelet configuration on control-plane (KUBELET_EXTRA_ARGS=--node-ip=10.x.x.x on workers) where 10.x.x.x is the private IP of the node.

Currently i use antrea as CNI with geneve link between the nodes (using the private node IP addresses).

I suggest that the HCCM checks not only a matching primary IP but also the configured private IP(s) - they are anyway available, for example i can extract this way (for FQDN servername):

hcloud server list -o json | jq -r ".[] | select(.name == "$(hostname -f)") | .private_net[].ip"

or for non FQDN servernames:

hcloud server list -o json | jq -r ".[] | select(.name == "$(hostname)") | .private_net[].ip"

Expected behavior

I wish to have the possibility to use FQDN servenames and a private IPs as node IPs with HCCM.

Best regards,
Robert

[apricote]

Hello @tehnic-take3,

FQDN Server Names

where do you use the FQDN server names?

By default hcloud-cloud-controller-manager requires that the name of the Kubernetes Node matches the name of the Server in the Hetzner Cloud / Robot APIs. This is documented here (very hard to find if you do not know that this exists).

Private IPs

If you want to use your private ips, this is already supported in hcloud-cloud-controller-manager.

In the helm chart you can enable this through the option networking.enabled: true.

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