We can use the govuk-design-system-redirect app as a starting point for the app code; I've already made a start on this at https://github.com/alphagov/prototype-kit-training-redirect, it just needs the redirect directive in the nginx config to be replaced with a reference to a HTML file with the desired content.

That content may or may not be styled with GOV.UK Frontend styles (I'd argue for not, because it makes maintenance much easier), but either way should be a single HTML file in the app root.

We can probably just deploy once to PaaS by hand, and then forget about it, as the use of the nginx buildpack makes the security of the site mostly their problem 😅

Draft content at end of this doc: https://docs.google.com/document/d/1jTPiZCie4_PTWaRo138gaKDEcH3yKNO9nN2hBGMY_HQ/edit#heading=h.2sedupo2wrni

Preview is available at http://prototype-kit-training-redirect.cloudapps.digital

I've just deployed alphagov/prototype-kit-training-redirect to PaaS, at the URL https://prototype-kit-training.cloudapps.digital.

I did this by logging in with the prototype-kit-docs account, and running the following commands in the repo:

cf push -f manifest.yaml -i 1
cf map-route prototype-kit-training-redirect cloudapps.digital --hostname prototype-kit-training
cf stop prototype-kit-training

This means that the redirect app has replaced the documentation app, and all future requests will be served by the redirect app. Deleting the documentation app will be done as part of #1175.

If for some reason the redirect app needs to be updated in future, a simple cf push will be all that is needed (as long as the app is not deleted).

I'm putting a note in the credentials repo linking back to this issue, so any devs wondering about this app might find there way here and to my notes.

Calling this done.