Rate Limiting through @rateLimit directive

Rate limiting is a technique for reducing server load by limiting the number of requests that can be made to a subgraph.

This approach follows the pattern of graphql-rate-limit.

To set rate limit hints in your subgraph schema, the @rateLimit directive definition should be included in the subgraph schema:

TODO: Implement this feature with a real example

directive @rateLimit(
  max: Int
  window: String
  message: String
  identityArgs: [String]
  arrayLengthField: String
) on FIELD_DEFINITION

Then in the subgraph schema, you can use the @rateLimit directive to set rate limit hints on fields:

type Query {
  getItems: [Item] @rateLimit(window: "1s", max: 5, message: "You are doing that too often.")
}

Field Configuration

• window: Specify a time interval window that the max number of requests can access the field. We use Zeit’s ms to parse the window arg, docs here.

• max: Define the max number of calls to the given field per window.

• identityArgs: If you wanted to limit the requests to a field per id, per user, use identityArgs to define how the request should be identified. For example you’d provide just [“id”] if you wanted to rate limit the access to a field by id. We use Lodash’s get to access nested identity args, docs here.

• message: A custom message per field. Note you can also use formatError to customise the default error message if you don’t want to define a single message per rate limited field.

• arrayLengthField: Limit calls to the field, using the length of the array as the number of calls to the field.