Implement a Read Only Flag to prevent any write operations

[dstufft]

There are times when we need to prevent any state modification on pypi.python.org but we do not need to prevent reading from the database or other storage areas. It would be great if we could prevent all write operations using a toggle somehow.

[ewdurbin]

A big red banner across the top of the web UI noting "Maintenance Mode" with a description of what that means would be a nice addition too.

[di]

@dstufft Any ideas about where would be the best place to short-circuit this? Perhaps a @db.listens_for(db.Session, "before_commit") or something to abort the commit?

[dstufft]

request.tm.doom() should allow the request to continue, but abort it at the last minute.