Resolve AIX hostname resolution issues

[sxa]

I suggest we adjust the AIX playbooks to set the hostname on the machine to match the inventory file. This would make it consistent with the other UNIX playbooks and ease the cross-platform system administration by providing consistent naming on the machines. The changes towards the end of last year to auto-deploy the playbooks on a regular basis have highlighted some concenrs in the issue below. In this proposal I am assuming that the use of the OSUOSL NIM server will not be affected. Let me know if I am mistaken on that.

Originally posted by @sxa in https://github.com/adoptium/infrastructure/issues/3178#issuecomment-1891645304

          As a follow-up to [the proposals above](https://github.com/adoptium/infrastructure/issues/3178#issuecomment-1888792438), noting that for other operating systems:

• We change the hostname in the UNIX playbooks to match the name from the inventory.yml file: https://github.com/adoptium/infrastructure/blob/d2303c7fa6daf3be310fac1f36c21da4c78a0de3/ansible/playbooks/AdoptOpenJDK_Unix_Playbook/roles/adopt_etc/tasks/main.yml#L25
• On windows we have logic to do a hostname change, but it's only invoked if the machine name ends in a hypen character: https://github.com/adoptium/infrastructure/blob/d2303c7fa6daf3be310fac1f36c21da4c78a0de3/ansible/playbooks/AdoptOpenJDK_Windows_Playbook/roles/Common/tasks/main.yml#L41 (From https://github.com/adoptium/infrastructure/issues/2133)

On this basis it is likely that making a similar change to the UNIX playbook on the AIX machines is the preferred option here, however given the proximity to the January release cycle I suggest we pause anything more for now (although comments/discussion on the options are still welcome) We could also use /etc/motd to remind people on login what the adoptXX name is (Similar to what we do for the RISC-V machines at the PLCTlab.

[aixtools]

afaik - the machines concept of it's hostname is not critical to it's operation. And, any affect it may have on the NIM setup can be updated in the NIM configuration files. I expect there will be an impact as AIX NFS uses the hostname as one of it's methods to authenticate a client connection (IP address and hostname that the client passes must match the servers hostname/IP resolution).

FYI: the hosts use the local /etc/hosts file first, and bind aka DNS only for addresses and names not in the local hosts file. Further, NIM is configured on the basis of in the private OSU networks, not the public networks.

Changing the hostname does not influence, not have any effect on the OSUOSL DNS names. Those are merely one of the ways to find the external IP address.

If you wish, I can do this manually - and you can have automated checks that it is still in place. (But I'll still not be a fan of these screen-wide hostnames ;) )

[aixtools]

footnote: looking at the playbook - please do not forget - and AIX is sensitive to this, especially when multi-homed and multi-stack - the HOSTNAME is the servername, not the name of an interface. An interface resolves to a FQDN - a hostname is not required to, and on AIX it is both common, and better practice, to leave the {{ Domain }} off the hostname.

Setting, and expecting a hostname to be paired to a specific interface name and protocol will likely break NIM because you are tying the hostname to the external interface while NIM operates using the internal interface. (NIM communication is permitted only on the internal interface).