Vary cached employer pages on authentication cookie

[hancush]

We do a little do-si-do in the employer views to show the standardized export button conditional on whether a user is authenticated. Unfortunately, we cache those views, so this dance is not repeated for each viewer, but rather the first viewer to visit the uncached page.

We should vary the cache based on the authentication cookie. Django docs on:

• vary_on_cookie
  • It doesn't look like you can specify a particular cookie, so not sure the effect of this in practice
• Decorating a class-based view method

It looks from analytics like a lot of traffic comes through person pages, i.e., a not insubstantial amount of employer views may be accessed for the first time by an unauthenticated user, because they aren't coming to the site through search, hiding the standardized data download, even for authenticated users. I don't think this is dire because the source document containing the same information is available to all users, regardless of authentication status, but wanted to note.

If we don't want to go down this rabbit hole, we could:

• Unconditionally show the standardized data download button, though this exposes a heavy request to a larger number of users
  • Investigate options for a lighter standardized data download, such as baking out the exports after upload or on first download and storing them as static assets in S3
• Not cache the employer views, though we'd incur a performance hit
• Implement a clientside authentication dance, though this is annoying with the current implementation of the authentication plug-in (my bad)
• Something else

[fgregg]

I'd like to unconditionally show the standardized data download button until we have evidence that it is causing a problem.

[fgregg]

@smcalilly, can you make that change

[smcalilly]

@fgregg yep, doing it now