Crate grafbase_sdk 

Grafbase SDK for Gateway Extensions

This crate provides building blocks for creating Grafbase Gateway extensions.

There exist four kinds of extensions today:

• AuthenticationExtension: Authenticates clients before any GraphQL processing, generating a token with custom data for further extensions.
• AuthorizationExtension: Control access to certain fields, objects, interfaces, scalars or enums.
• ResolverExtension: Called by the gateway to resolve data for a field from a GraphQL subgraph.
• HooksExtension: Called by the gateway to perform actions before receiving a request, or right before sending a response.
• ContractsExtension: Called by the gateway to identify which elements should be part of a schema contract given subgraph directives and the contract key.

Each extension has its dedicated documentation and tutorial you can follow through.

Features

• test-utils — Test utilities to write integration tests for your extension. The Grafbase CLI will automatically generate an example test with the grafbase extension init command. You can also check out Grafbase’s extension repository for examples
• jq-selection — Utilities to use jq-like selection to process data in your extension like the rest extension.

Modules

host_io

Host IO modules.

jq_selection

A module for performing JQ filter selections on JSON data.

test

Test utilities for running and interacting with a GraphQL gateway.

types

Type definitions of the input and output data structures of the SDK.

Structs

SdkError

Internal SDK error.

Traits

AuthenticationExtension

An authentication extension is called before any request processing, authenticating a user with a token or returning an error response.

AuthorizationExtension

An authorization extension can grant or deny access to fields, objects, interfaces, unions, scalars or enums. It’s composed of two parts:

ContractsExtension

The Contracts extension allows you to control which part of the schema will be exposed to clients for GraphQL queries, introspection and also the MCP endpoint if active.

HooksExtension

The Hooks extension allows you to hook into an incoming request or an outgoing response.

IntoAuthorizeQueryOutput

IntoOnRequestOutput

IntoSubscription

ResolverExtension

A resolver extension is called by the gateway to resolve a specific field.

Subscription

A trait for consuming field outputs from streams.

Derive Macros

AuthenticationExtension

A proc macro for generating initialization code for an authentication extension.

AuthorizationExtension

A proc macro for generating initialization code for an authentication extension.

ContractsExtension

A proc macro for generating initialization code for a contracts extension.

HooksExtension

ResolverExtension

A proc macro for generating initialization code for a resolver extension.