Best Way to Pass Request Headers to Executor #6049

Describe your proposal/problem

I've been looking for a way to pass http request headers to my Executor, and this is the only way I've been able to do it.

class MyGateway(FastAPIBaseGateway):
    @property
    def app(self):
        from fastapi import FastAPI

        app = FastAPI(title="Test Gateway")

        @app.get(path="/config")
        async def custom_endpoint(my_input: MyInput, request: Request):
            docs1: DocList[RequestOutput] = await self.executor["executor0"].post(
                on="/api/v0/test",
                inputs=DocList[Input]([my_input]),
                parameters=request.headers or {"no": "headers"},
                return_type=DocList[RequestOutput],
            )
            return docs1.to_json()

        return app

Is there a simpler way to do this? The approach above only works for flows, is there a way that works for deployments?

Environment

• jina 3.20.3
• docarray 0.33.0
• jcloud 0.2.16
• jina-hubble-sdk 0.39.0
• jina-proto 0.1.27
• protobuf 3.20.0
• proto-backend python
• grpcio 1.48.0rc1
• pyyaml 6.0.1
• python 3.9.17
• platform Darwin
• platform-release 22.6.0
• platform-version Darwin Kernel Version 22.6.0: Wed Jul 5 22:21:53
  PDT 2023; root:xnu-8796.141.3~6/RELEASE_ARM64_T6020
• architecture arm64
• processor arm
• uid 11592019587001
• session-id 0062ff1e-574c-11ee-9138-0a8afa35afb9
• uptime 2023-09-19T17:24:02.674004
• ci-vendor (unset)
• internal False

• JINA_DEFAULT_HOST (unset)
• JINA_DEFAULT_TIMEOUT_CTRL (unset)
• JINA_DEPLOYMENT_NAME (unset)
• JINA_DISABLE_UVLOOP (unset)
• JINA_EARLY_STOP (unset)
• JINA_FULL_CLI (unset)
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