Readonly Demo media

[gregorydlogan]

Occasionally we have situations where the dual stream demo event gets removed from our testing infrastructure. These events are used by other testing infrastructure (cf, the editor), which makes for broken test infrastructure in non-obvious ways. Ideally, we would have a way to make the required event read only, but in the meantime this (ab)uses the nginx proxy to refuse requests to do so.

What this stops:

• the admin UI's red X to delete the event
• the external API's ability to delete the event

What I'm unsure about:

• Graphql (which is probably disabled by default, but perhaps should be turned on?)

What this definitely doesn't handle:

• Starting a retract task. nginx doesn't seem to support munging based on post data (huh, wonder why...). If someone has an idea of how to do this, please let me know!