Feature Request: Support for Apollo Federation in Tailcall

[amitksingh1490]

Summary

Enable Tailcall to support Apollo Federation by adding a flag in the @server directive. When enabled, this flag will support the _entities query, allowing Tailcall to function as a subgraph in a federated architecture.

Detailed Description

To integrate Apollo Federation with Tailcall, we propose the following enhancements:

1. Flag Addition in @server:

   • Introduce a new flag within the @server directive to enable federation support.
   • When this flag is activated, Tailcall will automatically handle the _entities query, essential for Apollo Federation's distributed schema architecture.

2. Support for Resolver Directives on Types:

   • Enable resolver directives like @http, @grpc, @const, and others to be applied directly on Types.
   • This will allow Tailcall to infer the key fields required for federation based on the resolver configuration.

3. Key Inference:

   • Analyze the resolvers attached to Types and automatically infer the appropriate @key directive.
   • Example:
     • For @http(path: "/users/{{.value.id}}"), the inferred key would be @key(fields: "id").
     • For the query:

       @http(path: "/users/", query: [
       {key: "id", value: "{{.value.id}}"},
       {key: "name", value: "{{.value.name}}"},
       {key: "org_id", value: "{{.value.organisation.id}}"},
       {key: "org_name", value: "{{.value.organisation.name}}"}
       ])

       The inferred key would be @key(fields: "id name organisation {id, name}").

   • If multiple resolvers are attached to the same type, multiple keys will be inferred and handled accordingly.

4. Support for _entities Query:

   • Implement the _entities query required by Apollo Federation.
   • Example of how the query to the subgraph would look:

     type Query {
     _entities(representations: [_Any!]!): [_Entity]!
     }

     • Example query:

       query ($representations: [_Any!]!) {
       _entities(representations: $representations) {
       ... on User {
        id
        username
       }
       }
       }

     • Corresponding variable:

       {
       "representations": [
        {
          "__typename": "User",
          "id": "5"
        }
       ]
       }

References

• For a reference implementation of Apollo Federation, see the async-graphQL implementation.

• Subgraph Documentation

Technical Requirements

• Integration & Unit Tests are required.
• Update the documentation on website

[amitksingh1490]

/bounty 380$

[algora-pbc[bot]]

💎 $380 bounty • Tailcall Inc.

Steps to solve:

1. Start working: Comment /attempt #2639 with your implementation plan
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Attempt	Started (GMT+0)	Solution
🔴 @onyedikachi-david	Aug 10, 2024, 7:00:15 PM	WIP
🟢 @meskill		#2693

[onyedikachi-david]

/attempt #2639

Algora profile	Completed bounties	Tech	Active attempts	Options
@onyedikachi-david	3 tailcallhq bounties + 2 bounties from 1 project	JavaScript, Shell		Cancel attempt

[ssddOnTop]

please provide some working config

[algora-pbc[bot]]

@onyedikachi-david: Reminder that in 1 days the bounty will become up for grabs, so please submit a pull request before then 🙏

[algora-pbc[bot]]

The bounty is up for grabs! Everyone is welcome to /attempt #2639 🙌

[algora-pbc[bot]]

💡 @meskill submitted a pull request that claims the bounty. You can visit your bounty board to reward.