Router v2.2.1 can't handle progressive overrides < 100%

[oliverjumpertz]

Describe the bug

We have three subgraphs:

1. Subgraph A (old subgraph to be replaced)
2. Subgraph B (new subgraph. new tech stack. Should replace A)
3. Subgraph C (provides other metadata)

Subgraph A provides image metadata that is federated into entities from subgraph C. Subgraph B is now to take over the image metadata from subgraph B and thus tries to apply progressive overrides for the migration.

Subgraph A has all fields of the entities in question annotated with @shareable, Subgraph B has the same fields annotated with @override and a label with the corresponding percent for the override. Subgraph A additionally lets the type implement an interface, subgraph B doesn't.

If we now apply any percentage less than 100 to the entity fields in question, Router encounters a federation error when entities from subgraph C are fetched with federated entities from subgraph A/B.

To Reproduce

Take a subgraph A with the following schema:

interface IImage {
  id: ID! 

  absoluteUri: String! 
}

type Image implements IImage @key(fields: "id") {
  id: ID! @shareable

  absoluteUri: String! @shareable
}

extend type AssetMetadata @key(fields: "id") {
  id: ID! @external

  image: Image @shareable
}

Then take a subgraph B with the following schema:

type Image @key(fields: "id") {
  id: ID!

  absoluteUri: String! @override(from: "subgraphA", label: "percent(1)")
}

type AssetMetadata @key(fields: "id") {
  id: ID! @external

  image: Image @override(from: "subgraphA", label: "percent(1)")
}

And subgraph C with the following schema:

type Query {
  assetMetadata(id: ID!): AssetMetadata
}

type AssetMetadata @key(fields: "id") {
  id: ID!

  name: String!
}

Issuing the following query:

query TestQuery($id: ID!) {
  assetMetadata(id: $id) {
    __typename
    id
    name
    image {
      absoluteUri
    }
  }
}

Leads to the following error:

{
  "data": null,
  "errors": [
        {
            "message": "value retrieval failed: Federation error: An internal error has occurred, please report this bug to Apollo.\n\nDetails: Was not able to find any options for absoluteUri: This shouldn't have happened.",
            "extensions": {
                "code": "INTERNAL_SERVER_ERROR"
            }
        }
    ]
}

Expected behavior

Progressive override should work with any percentage less than 100 and should not lead to the issues described.

Output

The Router delivers the following output when a property from an entity handled by the affected subgraphs is requested:

{
  "data": null,
  "errors": [
        {
            "message": "value retrieval failed: Federation error: An internal error has occurred, please report this bug to Apollo.\n\nDetails: Was not able to find any options for absoluteUri: This shouldn't have happened.",
            "extensions": {
                "code": "INTERNAL_SERVER_ERROR"
            }
        }
    ]
}

Environment:

• Apollo Rover 2.2.1 deployed to Kubernetes

Additional context

Nothing right now. Happy to add more if necessary.