Improve interfaces templates: allow word expansion

[fser]

Environment

• Python version: 3.7
• NetBox version: 2.6.6

Proposed Functionality

In the template interface, allow user to expand names. For example Interface/[FRONT|BACK]/Eth[1-10] would produce:

Interface/FRONT/Eth1
Interface/FRONT/Eth2
Interface/FRONT/Eth3
Interface/FRONT/Eth4
Interface/FRONT/Eth5
Interface/FRONT/Eth6
Interface/FRONT/Eth7
Interface/FRONT/Eth8
Interface/FRONT/Eth9
Interface/FRONT/Eth10
Interface/BACK/Eth1
Interface/BACK/Eth2
Interface/BACK/Eth3
Interface/BACK/Eth4
Interface/BACK/Eth5
Interface/BACK/Eth6
Interface/BACK/Eth7
Interface/BACK/Eth8
Interface/BACK/Eth9
Interface/BACK/Eth10

Use Case

We need such expansion pattern for our device templates. Maybe others do as well!

Database Changes

None

External Dependencies

None

[kobayashi]

Thank you for opening this issue.
Could you let me know what kind of devices have both front/back interface?

[fser]

Hello,

from my understanding, mostly patch panels.

[DanSheps]

Are you using interfaces or front/rear ports?

[jeremystretch]

Two thoughts. First, we should stick to comma-delimited values since that's the current convention. Second, we should be able to tweak parse_alphanumeric_range() to simply ignore values which don't specify a range and pass them through.

[fser]

Sorry for the delay!
@DanSheps : I asked my colleague, and he told me he uses interfaces because the "front/back" thing didn't exist at the time when they created the template. Does that answer your question?

@jeremystretch : I tried to tweak it using commas (by the way, why does the regex allow so many delimiter [?:,-] if only the coma is valid?) but I couldn't identify the case where expansion was required instead of enumeration. See my PR if that can be relevant.

Thanks anyway for the interest!