fix: allow FQDNs as controlPlaneEndpoint

[pborn-ionos]

Issue #, if available:
fixes #153

Description of changes:
Checks if the passed controlPlaneEndpoint.host is a resolvable FQDN, and if true, uses the IP from it for further validation.

Testing performed:
See chat.

[mcbenjemaa]

This still accepts ip address ?

[pborn-ionos]

@mcbenjemaa yes. Just double checked it and added some testcases for plain ipv4 / ipv6 endpoints.

After all, all we do here is, prior to running our actual tests, checking if the controlPlaneEndpoint is a resolvable FQDN and if so, continue with it's IP :)

[65278]

This works, but is a bit awkward. Since we agreed that I'll be taking over, no further action is required.

A couple of remarks:

• isValidFQDN is actually a test if a hostname resolves, and has nothing to do with FQDNs. There's no requirement on a hostname needing to be an FQDN to be valid.
• You can resolve hostnames which are illegal as actual hostnames. As an example, _acme-challenge.your.domain is valid to resolve, but not a hostname. This is useful for text type records.
• We're now implicitly depending on endpointHostIP not returning square brackets. I don't think this assumption holds

[pborn-ionos]

• We're now implicitly depending on endpointHostIP not returning square brackets. I don't think this assumption holds

It does and we should not accept them here. Otherwise we have to strip them again in other places, where it is passed to other resources. We've already been there and passing a controlplaneEndpoint.Host like [::1] just caused issues during provisioning.

[mcbenjemaa]

I have tested ipv6, but it doesn't work for proxmoxcluster. But the cluster was created successfully

cluster.cluster.x-k8s.io/test-dev created
  1 err  kind-vault-onboard kube 
Warning: cannot create proxmox cluster test-dev
The ProxmoxCluster "test-dev" is invalid: spec.controlplaneEndpoint: Invalid value: "[2a01:c23:61ce:d200::ff6:99bf:cf43]": provided endpoint address is not a valid IP or FQDN

also when i put a hostname in the controlplaneendpoint, it works for cluster but not for ProxmoxCluster.

those cases don't work:

• test.example.com
• test-dev
• "[2a01:c23:61ce:d200::ff6:99bf:cf43]"
• "nginx.nginx.svc.cluster.local"

[pborn-ionos]

With square brackets is not supposed to work. And if the other ones don't resolve, they're not supposed to work either, as with my change the IP behind the FQDN is required for further endpoint validation.

[mcbenjemaa]

CAPI doesn't have any validation for this field, i think you can omit validation for the host.

[pborn-ionos]

Either we validate the host, or we ditch the validateIPs function altogether. But then it should be kept in mind, that that function also validates, whether or not the given controlPlaneEndpoint collides with the cluster's given IP ranges.

[mcbenjemaa]

We keep validations of IPs of the ipam, and the validation of collides with endpoint ip.
and we omit all validation to the endpoint host.
let's just keep it simple. then capi will actually through an error if the endpoint is not correct.

[mcbenjemaa]

The workaround, in my opinion, is to let the user choose the control-plane endpoint, with no further validation,
and if the user chose a wrong endpoint , then capi will actually through an error state:

[wikkyk]

fixes #153

[mcbenjemaa]

I have raised this PR, that will make cluster to fail if machine has failed cloud-init run:
#166

[65278]

This is done here. The PR is rather small, a couple of naming changes and a function to detect hostnames.
We error if our target is not an ip or a valid hostname, otherwise anything goes.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud