Consistently replace '_' with '-' in hostnames

[jbemmel]

It is not a valid FQDN character, and some platforms (like Cumulus NVUE) fail with an error

We could consider restricting node names to be valid FQDNs (of at most 16 characters), and/or apply the 'replace' normalization in Python rather than all templates (either define a node.hostname property and use that everywhere instead of inventory_hostname, or change inventory_hostname (and issue an error when troublesome node names are used)

[ipspace]

There is no need for such a change. Many platforms accept both.

Whichever platform cannot deal with a valid node identifier should solve its own issues in a configuration template.

Also:

• Did you test all these changes? Are you sure they work?
• Why did you not change the hostname mappings if you want to enforce consistency?

Just because you have a problem with NVUE does not mean everything else has to change. Submit a PR for those platforms that cannot handle '_' and I'll merge it.

[jbemmel]

There is no need for such a change. Many platforms accept both.

Whichever platform cannot deal with a valid node identifier should solve its own issues in a configuration template.

Also:

• Did you test all these changes? Are you sure they work?
• Why did you not change the hostname mappings if you want to enforce consistency?

Just because you have a problem with NVUE does not mean everything else has to change. Submit a PR for those platforms that cannot handle '_' and I'll merge it.

Many platforms accept both, Ubuntu for example simply ignores the '_' characters and a r_1 hostname becomes r1.

Most of the platforms I have access to - eos, cumulus, dell os10, linux - use the character substitution. The immediate issue was with Cumulus NVUE, but - for example - Cisco AVA is reported to have similar issues.

I think users would be better off if they stayed away from using '_' in hostnames, lacking that the next best thing is - imho - to replace '_' with '-', rather than let it be ignored and hope it doesn't cause issues. We could make that configurable, while I did not test the other platforms I think it is reasonable to expect the hostname to work at least as well with a '-', and possibly better.

I can submit a PR for only Cumulus NVUE, I do not have access to most other platforms so I don't really care for myself. But I thought it'd be nice for the community

[ipspace]

I can submit a PR for only Cumulus NVUE

You should have done that in the first place.

I do not have access to most other platforms so I don't really care for myself.

Copiously illustrated in #1623.

Also: stop "fixing" stuff you don't care about and have no intention of testing.

But I thought it'd be nice for the community

Maybe it's just me, but in my personal opinion the community might appreciate a tested and working software more.