Resolving different schemes for one service with two pods.

[SpeedyGonzaless]

I have run apollo gateway in k8s and service MyTestService.

const gateway = new ApolloGateway({
    supergraphSdl: new IntrospectAndCompose({
        subgraphs: [
            { name: 'test-serivice', url: 'http://test-service-svc/graphql' }
        ],
        pollIntervalInMs: 5000
    })
});

MyTestService has two pods. At first both pods has the same schema:

type Query {
    getClient(
        id: Int,
    ): [Client]
}

type Client {
    id: Int,
    name: String
}

Then I change Client schema in code to this:

type Client {
    id: Int,
    name: String,
    newTestField: String
}

And I restart only one pod of MyTestService. So for now, first pod has old schema and second pod has new schema.
Is it somehow possible not to allow me as a client use field 'newTestField' in request until all the pods will have this new field?

[trevor-scheer]

Apollo Studio solves this problem using a schema registry. You push changes to the registry once your service can accept queries with those changes, and that is the schema that your gateway recognizes. We don't recommend IntrospectAndCompose for production use and this is one of the main reasons. In any case, the abstract solution here is that you need a single source of truth for your schema that your clients write queries against and is only updated to reflect schema changes when they are valid across all of your pods.