1. Created a new branch from the commit before cat17 was deleted, changed the campaign configuration to be able to switch skins until the end of 2025, see https://github.com/wmde/FundraisingFrontend/tree/skin-archive
2. I've asked IT to create the new subdomain and point it at the IP of our test server. Ticket No is 2020021420000332
3. Prepared the Nginx on the test server with a new vhost. See https://github.com/wmde/fundraising-infrastructure/pull/291
4. Added an inventory file for the new target to FundraisingFrontend/deployment/inventory/skin_archive on the deploy server
5. Added the new configuration file for the instance in configurations/spenden-old-designs.wikimedia.de/config.uat.json

I have successfully deployed the archive. There was one snag however - the content repository with the in-application messages and translations. I've configured the application to use the one installed in vendor. However, that is a dev dependency, which does not get deployed normally. There are three solutions for this:

• Do nothing, never deploy the skin archive again (or run into the same puzzling behavior again in 6-24 months, spending 30-60 mins of debugging).
• Manually check out the content repo in a different path and point the configuration to it. Since the only "documentation" for this is the config file, we might run into the error when migrating the skin archive to the new servers.
• Fix the Ansible deployment script to allow to run composer again with a configurable --no-dev flag. Our switch to Docker and Makefiles dropped the configurability, but there are vestiges of the setting in the inventory files

The content is now part of the skin_archive branch, no extra dependency needed. The deployment script creates a symlink to content/resources which will fail the first time the branch is deployed. I've worked around that by using the content repo from "test-spenden-2" - the resources are not likely to change.