netdog: check platform-specific mechanism for getting hostname first

[etungsten]

Issue number:

Addresses #3011 and potentially #3013

Description of changes:

    netdog: check platform-specific mechanism for getting hostname first
    
    Instead of looking up the hostname via reverse DNS look up first, we
    first try any platform-specific mechanism for retrieving hostnames. For
    AWS varaints, this means to query IMDS for the hostname first. This
    gives up a more authoritative hostname to set for the host.

Testing done:
Launched aws-k8s-1.26 into a subnet with hostname type set to "Resouce name".

The node comes up successfully with the node named with its resource name:

$ kubectl get nodes -o wide
NAME                                             STATUS   ROLES    AGE    VERSION               INTERNAL-IP      EXTERNAL-IP      OS-IMAGE                                KERNEL-VERSION   CONTAINER-RUNTIME
i-1234abcdef.us-west-2.compute.internal   Ready    <none>   104m   v1.26.2-eks-b106822   192.168.16.9     <none>           Bottlerocket OS 1.14.0 (aws-k8s-1.26)   5.15.102         containerd://1.6.19+bottlerocket

In older variants (aws-k8s-1.24) that still uses the in-tree AWS cloud provider code in kubelet, the node joins fine.

NAME                                             STATUS   ROLES    AGE     VERSION                INTERNAL-IP       EXTERNAL-IP      OS-IMAGE                                KERNEL-VERSION   CONTAINER-RUNTIME
i-1234abcdef.us-west-2.compute.internal   Ready    <none>   70s     v1.24.10-eks-08ad9cc   192.168.27.156    34.215.149.50    Bottlerocket OS 1.14.0 (aws-k8s-1.24)   5.15.102         containerd://1.6.19+bottlerocket

Terms of contribution:

By submitting this pull request, I agree that this contribution is dual-licensed under the terms of both the Apache License, version 2.0, and the MIT license.

[stmcginnis]

Tested with an aws-k8s-1.24 node to check for any regression issues.

NAME                                           STATUS   ROLES    AGE    VERSION                INTERNAL-IP      EXTERNAL-IP      OS-IMAGE                                KERNEL-VERSION   CONTAINER-RUNTIME
ip-192-168-94-139.us-east-2.compute.internal   Ready    <none>   4m2s   v1.24.10-eks-08ad9cc   192.168.94.139   18.216.220.116   Bottlerocket OS 1.14.0 (aws-k8s-1.24)   5.15.102         containerd://1.6.19+bottlerocket

$ k apply -f ../testing/test-pod.yaml
pod/webserver created

$ k get pod
NAME READY STATUS RESTARTS AGE
webserver 1/1 Running 0 7s

No issues found. Joined cluster fine and appears to be operational.

[zmrow]

This seems ok. For non-AWS variants the platform-specific call is essentially a no-op and then the logic remains the same. I'm not sure there exists a case in AWS where you wouldn't want to use the IMDS supplied hostname? 🤔

There are a few spelling errors in the commit message:

For aws varaints should be For AWS variants

and

more authoratative should be more authoritative

[etungsten]

Push above fixes commit message.