We want to put the legacy deployment in a state where

• artifact and index URLs continue to work
• users of login.taskcluster.net for third-party login continue to get credentials for the Firefox-CI deployment

I think that looks like:

• terminate all EC2 instances, turn off aws-provisioner, ec2-manager
• turn off all services except auth, queue, index, and login
• turn off background jobs for those (esp the index listener)
• turn off sign-in on tools and tc-ui
• give tc-login creds for new firefox cluster
• delete all clients except those for queue and index, and especially delete the old login client (invalidates temp creds)
• deploy versions of auth, queue, and index that disable modifications by just deleting the relevant API methods (updateRole, createClient, createTask, cancelTask, indexTask, etc.)

https://github.com/taskcluster/taskcluster/pull/1192 should handle the "read-only" bit. On review, I'll land that in a branch on the monorepo.

Do you see other things we would need to do, or problems with the list in the previous comment?

Yeah, that's all I can really think of too.

PR branch pushed to bug1574230 in the monorepo.