Added node-public-ip annotation

[rbrtbnfgl]

Description

This change the behave added in #1948 to fix #1978
It adds two new annotation node-public-ip and node-public-ipv6 to use instead.

Todos

• Tests
• Documentation
• Release note

Release Note

None required

[manuelbuil]

• flannel.alpha.coreos.com/node-public-ip, flannel.alpha.coreos.com/node-public-ipv6: Optionally set by the user, it defines the IP of the node for pod communications. It will be used to select the local interface, e.g. for the vxlan vtep. Flanneld will, later, use it as value for flannel.alpha.coreos.com/public-ip and flannel.alpha.coreos.com/public-ipv6

• flannel.alpha.coreos.com/public-ip, flannel.alpha.coreos.com/public-ipv6: Set by flanneld informs of the node IP chosen for pod communication. This value is used by the rest of nodes to find the destination IP for the node.

• flannel.alpha.coreos.com/public-ip-overwrite, flannel.alpha.coreos.com/public-ipv6-overwrite optionally set by the user, defines the IP of the node that will be announced to the rest for pod communications, e.g. the vtep of vxlan. Unlike the node-public-ip annotation, the IP does not need to be part of a local interface as this value has no influence on the vtep creation, only on the announcement of the node IP for the rest of the nodes. This annotation should only be used if the node is behind a NAT. It can be automatically set to a nodes ExternalIP using the flannel-node-annotator.See also the "NAT" section in troubleshooting if UDP checksums seem corrupted. See also the "NAT" section in troubleshooting if UDP checksums seem corrupted.