Way to enable a default=False permission for anonymous users

[simonw]

I'd like plugins to be able to ship with a default that says "anonymous users cannot do this", but allow site administrators to over-ride that such that anonymous users can use the feature after all.

This is tricky because right now the anonymous user doesn't have an actor dictionary at all, so there's no key to match to an allow block.

[simonw]

Idea: the anonymous actor could be passed to actor_matches_allow() as:

{"anonymous": true}

Then allow blocks like this could be used to allow them:

{
    "plugins": {
        "datasette-upload-csvs": {
            "allow": {
                 "anonymous": true
            }
        }
    }
}

[simonw]

I'm torn between anonymous and anon - because the latter is less typing, and I envisage people writing a lot of code like this:

    if actor.get("anonymous"):
        # ...

I'm going with anonymous because it's that tiny bit clearer than anon.

[simonw]

Alternative design: leave actor alone. Instead specify that allow blocks can look like this:

{
    "allow": {
        "unauthenticated": true
    }
}

I like this: the above block is very self-documenting.

The "id": "*" mechanism means there is already precedent for allow keys with special meaning.

I'm going with this design.

[simonw]

When I implement this I should also document default allow vs default deny as a concept, and specify that default next to every documented permission.

[simonw]

Documented at the bottom of this section: https://github.com/simonw/datasette/blob/7633b9ab249b2dce5ee0b4fcf9542c13a1703ef0/docs/authentication.rst#defining-permissions-with-allow-blocks

[simonw]

https://datasette.readthedocs.io/en/latest/authentication.html#defining-permissions-with-allow-blocks