`rover subgraph introspect` support for dynamically calculated AWS SignatureV4 headers

[prasek]

Description

rover subgraph introspect generates a _service { sdl } query, but for services created and authenticated using AWS IAM it requires passing AWS auth headers as part of the request for rover subgraph introspect to succeed.

It may be possible to manually generate the auth --header for rover subgraph introspect by signing the query that rover is making e.g.

query _service {
  _service {
    sdl
  }
}

and passing those AWS auth headers in via rover subgraph introspect --header but would be leaking the specifics of how rover is doing introspection and the exact query used, and be more complicated for users, like

• https://github.com/apollographql/federation/issues/1784

How can we help?

• support a rover flag that allows automatically generating a SignatureV4 header, perhaps along the lines of the defaultProvider so I don't have to manually construct a --header for rover subgraph introspect