Add working example for setting up local prod docker image.

[tpendragon]

Closes #301

We might want to set this up in a docker-compose at some point..

[github-actions]

Container Scanning Status: ✅ Success

ghcr.io/pulibrary/dpul-collections:pr-302 (debian 12.6)
=======================================================
Total: 0 (HIGH: 0, CRITICAL: 0)

[hackartisan]

this works thank you! I have one comment but it's not a blocker.

insight as to which change fixed the "can't set long node name" error?

[hackartisan]

It seems like this could just be true woudl that be more straightforward? See https://hexdocs.pm/phoenix/Phoenix.Endpoint.html#socket/3-common-configuration

and looking at the host in prod:

iex([email protected])1> DpulCollectionsWeb.Endpoint.config(:url)[:host]
"dpul-collections-staging.lib.princeton.edu"

[tpendragon]

Works for me!

[tpendragon]

insight as to which change fixed the "can't set long node name" error?

#117 is what did it. The argument that caused it was https://github.com/pulibrary/dpul-collections/pull/117/files#diff-3ecf6eeecfdb632f12cc8e3aae2fe865e0c643923f93166bf4c3a9d149364effR20 - RELEASE_IP wasn't set.