HTTP static caching for GraphQL

[timkelty]

GraphQL request are POST, and thus not inherently cacheable on the HTTP-level. That said, GQL requests could include a unique hash that Cloud could potentially use as a cache key.

[PhilReinking]

@timkelty found this here through the roadmap and thought this is a good place to mention the APQ extension here.

https://www.apollographql.com/docs/apollo-server/performance/apq#using-get-requests-with-apq-on-a-cdn

from the apollo graphql docs:

A great application for APQ is running Apollo Server behind a CDN. Many CDNs only cache GET requests, but many GraphQL queries are too long to fit comfortably in a cacheable GET request. When the APQ link is created with createPersistedQueryLink({useGETForHashedQueries: true}), Apollo Client automatically sends the short hashed queries as GET requests enabling a CDN to serve those requests. For full-length queries and for all mutations, Apollo Client will continue to use POST requests.

In our setup we use urql-graphql that comes with an APQ client extension, so unpersisted queries require two calls at first:

1. GET with hashed query
2. POST with full query

The same query would then only call:

1. GET with the hashed query parameter

This is then cachable just as any other standard GET request.

I would say that this is probably the best way to add cachable GraphQL queries, since it does not add any custom cache key logic and some client-side libraries already support APQ along with GET requests.