Retire isle-dc in favour of Isle Site Template

[joshdentremont]

We have started some conversations in the tech call and in slack (https://islandora.slack.com/archives/CM6F4C4VA/p1701889449425439) about retiring isle-dc and putting all of our efforts into the site template moving forward.

I'm creating this issue so we can start mapping out the process, but we will probably need to create several smaller issues along the way.

My suggestion is to do the following:

1. Create instructions for converting a site from isle-dc to the site template
2. Update our Docker documentation to be about the site template only
   a. Most of what we have now is about isle-dc, but a lot of it covers both install methods
3. Archive Isle-dc as is
4. Add documentation around how to do the things we have in the isle-dc Makefile
   a. Things like backing up, transferring site configuration, etc.
   b. We could also create example makefiles (or use another tool) that are separate to the site template repository that may cover different use cases
5. Add more documentation on how to modify the site template to suit your needs
   a. Things like using your own certs instead of lets encrypt, adding support for a staging site, removing containers you don’t use like matomo or fedora, etc.
   b. We should probably also look at all the variables in isle-dc's sample.env and make sure we are documenting how to modify them with the site template

This should also solve the issue posed here (#2236)

[rosiel]

This was discussed at the Tech Call and TAG today, and while there were some concerns, it seems prudent to move forward in this direction.

It should be mentioned that the philosophy of the Site Template is starkly different from that of ISLE-DC. The Site Template is a download-it-once-and-its-yours repository, where updates are NOT available for download. On the other hand, ISLE-DC tries to keep you "up to date" in many ways (more than it probably should).

I think the sentiment at TAG was that we want to spend less time maintaining ways to start up islandora and more time on islandora code itself. The Site Template has less of a maintenance burden, so seems to be the better option. also it's less in the way of users learning Docker (as it doesn't hide any docker commands behind abstractions) and that's useful for getting people up to speed as they need to be to run islandora in production.

It was noted that the makefile contains many useful commands that are hard to execute otherwise (such as exporting your database or importing/exporting configs) and so having a makefile available - either part of the Site Template or elsewhere - with the relevant code would be appreciated.

It would be good to see a fleshed-out list (scoping doc, I guess) that lists the elements part of 4a and 5a/b of the above list.