[EPIC] Create Gateway Service

[nnnnat]

Create Gateway Service

In this EPIC we'll create the actual Federated Gateway service. Our Gateway will need to use Apollo Gateway and conform to the Apollo Federation spec.

User Stories

• As a developer I should be able to add services to the Gateway via an .env variable.
• As a developer I should be able to query through the Gateway endpoint and view federated data from across the reaction node and pricing engine services.
• As a developer I need to enforce system level permissions in the Gateway: [EPIC] IAM Integration #4

Acceptance Criteria

• Gateway service available that includes Reaction 3.0 API and the Pricing Engine API.
• We can query products from the Gateway and see Pricing Engine data included.
• Verify system level access control is working.

Consideration

The Gateway services it's self is a pretty small application and most examples show it being used directly with Apollo Server. I think it's worth the effort to create the Gateway using a more common node.js server (express, hapi, koa, etc) and provide Apollo via a middle-ware, this will give us a little more granular control of the server it's self and removes some of the apollo magic.