graphql-shield

GraphQL Server permissions as another layer of abstraction!

Overview

GraphQL Shield helps you create permission layer for your application. Using intuitive rule-API, you'll gain the power of shield engine on every request and reduce the load time of every request with smart caching. This way you can make sure your application will remain quick, and no internal data will be exposed.

Features

✂️ Super Flexible: Based on GraphQL Middleware.
😌 Super easy to use: Just add permissions to your Yoga middlewares set, and you are ready to go!
🤝 Compatible: Works with all GraphQL Servers.
🚀 Blazing fast: Intelligent V8 Shield engine caches all your request to prevent anything from being called too many times.
🎯 Per-Type: Write permissions for your schema, types or specific fields (check the example below).
💯 Tested: Very well tested functionalities!

Install

yarn add graphql-shield

Example

import { GraphQLServer } from 'graphql-yoga'
import { rule, shield, and, or, not } from 'graphql-shield'

const typeDefs = `
  type Query {
    frontPage: [Fruit!]!
    fruits: [Fruit!]!
    cusomers: [Customer!]!
  }

  type Mutation {
    addFruitToBasket: Boolean!
  }

  type Fruit {
    name: String!
    count: Int!
  }

  type Customer {
    id: ID!
    basket: [Fruit!]!
  }
`

// Rules

const isAuthenticated = rule()(async (parent, args, ctx, info) => {
  return ctx.user !== null
})

const isAdmin = rule()(async (parent, args, ctx, info) => {
  return ctx.user.role === 'admin'
})

const isEditor = rule()(async (parent, args, ctx, info) => {
  return ctx.user.role === 'editor'
})


// Permissions

const permissions = shield({
  Query: {
    frontPage: not(isAuthenticated),
    fruits: and(isAuthenticated, or(isAdmin, isEditor)),
    customers: and(isAuthenticated, isAdmin)
  },
  Mutation: {
    addFruitToBasket: isAuthenticated,
  },
  Fruit: isAuthenticated,
  Cusomer: isAdmin
})

const server = GraphQLServer({
  typeDefs,
  resolvers,
  middlewares: [permissions],
})

server.start(() => console.log('Server is running on http://localhost:4000'))

API

Types

// Rule
function rule(name?: string, options?: IRuleOptions)(func: IRuleFunction): Rule

type IRuleFunction = (
  parent: any,
  args: any,
  context: any,
  info: GraphQLResolveInfo,
) => Promise<boolean>

export interface IRuleOptions {
  cache?: boolean
}

// Logic
function and(...rules: IRule[]): LogicRule
function or(...rules: IRule[]): LogicRule
function not(rule: IRule): LogicRule

// Predefined rules
const allow: Rule
const deny: Rule

type IRule = Rule | LogicRule

interface IRuleFieldMap {
  [key: string]: IRule
}

interface IRuleTypeMap {
  [key: string]: IRule | IRuleFieldMap
}

type IRules = IRule | IRuleTypeMap

function shield(rules?: IRules, options?: IOptions): IMiddleware

export interface IOptions {
  debug?: boolean
}

`shield(rules?, options?)`

Generates GraphQL Middleware layer from your rules.

`rules`

A rule map must match your schema definition. All rules must be created using rule function to ensure caches are made correctly. You can apply your rule accross entire schema, Type scoped, or field specific.

Limitations

All rules must have a distinct name. Usually, you won't have to care about this as all names are by default automatically generated to prevent such problems. In case your function needs additional variables from other parts of the code and is defined as a function, you'll set a specific name to your rule to avoid name generation.

// Normal
const admin = rule({ cache: true })(async (parent, args, ctx, info) => true)

// With external data
const admin = bool =>
  rule(`name`, { cache: true })(async (parent, args, ctx, info) => bool)

Cache is enabled by default accross all rules. To prevent cache generation, set { cache: false } when generating a rule.
By default, no rule is executed more than once in complete query execution. This accounts for significantly better load times and quick responses.

`options`

Property	Required	Default	Description
debug	false	true	Toggles catching internal resolvers errors.

By default shield ensures no internal data is exposed to client if it was not meant to be. Therfore, all thrown errors during execution resolve in Not Authenticated! error message if not otherwise specified using CustomError. This can be turned off by setting debug option to true.

`allow`, `deny`

GraphQL Shield predefined rules.

allow and deny rules do exactly what their names describe.

`and`, `or`, `not`

and, or and not allow you to nest rules in logic operations.

Nested rules fail by default if error is thrown.

And Rule

And rule allows access only if all sub rules used return true.

Or Rule

Or rule allows access if at least one sub rule returns true and no rule throws an error.

Not

Not works as usual not in code works.

import { shield, rule, and, or } from 'graphql-shield'

const isAdmin = rule()(async (parent, args, ctx, info) => {
  return ctx.user.role === 'admin'
})

const isEditor = rule()(async (parent, args, ctx, info) => {
  return ctx.user.role === 'editor'
})

const isOwner = rule()(async (parent, args, ctx, info) => {
  return ctx.user.items.some(id => id === parent.id)
})

const permissions = shield({
  Query: {
    users: or(isAdmin, isEditor)
  },
  Mutation: {
    createBlogPost: or(isAdmin, and(isOwner, isEditor))
  }
  User: {
    secret: isOwner
  },
})

`Custom Errors`

Shield, by default, catches all errors thrown durign resolver execution. This way we can be 100% sure none of your internal logic will be exposed to the client if it was not meant to be.

Nevertheless, you can use CustomError error types to report your custom error messages to your users.

import { CustomError } from 'graphql-shield`

const typeDefs = `
  type Query {
    customError: String!
  }
`

const resolvers = {
  Query: {
    customError: () => {
      throw new CustomError('customErrorResolver')
    },
  }
}

const permissions = shield()

const server = GraphQLServer({
  typeDefs,
  resolvers,
  middlewares: [permissions]
})