@envelop/generic-auth

This plugin allows you to implement custom authentication flow by providing a custom user resolver based on the original HTTP request. The resolved user is injected into the GraphQL execution context, and you can use it in your resolvers to fetch the current user.

The plugin also comes with an optional @auth directive that can be added to your GraphQL schema and helps you to protect your GraphQL schema in a declarative way.

There are several possible flows for using this plugin (see below for setup examples):

• Option #1 - Complete Protection: protected the entire GraphQL schema from unauthenticated access. Allow unauthenticated access for certain fields by annotating them with a @skipAuth directive or skipAuth field extension.
• Option #2 - Manual Validation: the plugin will just resolve the user and injects it into the context without validating access to schema field.
• Option #3 - Granular field access by using schema field directives or field extensions: Look for an @auth directive or auth extension field and automatically protect those specific GraphQL fields.

Getting Started

Start by installing the plugin:

yarn add @envelop/generic-auth

Then, define your authentication methods:

1. Resolve your user from the request by implementing resolveUserFn:

Use this method to only extract the user from the context, with any custom code, for example:

import { ResolveUserFn } from '@envelop/generic-auth'

type UserType = {
  id: string
}

const resolveUserFn: ResolveUserFn<UserType> = async context => {
  // Here you can implement any custom sync/async code, and use the context built so far in Envelop and the HTTP request
  // to find the current user.
  // Common practice is to use a JWT token here, validate it, and use the payload as-is, or fetch the user from an external services.
  // Make sure to either return `null` or the user object.

  try {
    const user = await context.authApi.authenticateUser(context.req.headers.authorization)

    return user
  } catch (e) {
    console.error('Failed to validate token')

    return null
  }
}

2. Define an optional validation method by implementing validateUser:

This method is optional; the default method will just verify the value returned by resolveUser and throw an error in case of a false value (false | null | undefined).

import { ValidateUserFn } from '@envelop/generic-auth'

const validateUser: ValidateUserFn<UserType> = params => {
  // Here you can implement any custom to check if the user is valid and have access to the server.
  // This method is being triggered in different flows, based on the mode you chose to implement.

  // If you are using the `protect-auth-directive` mode, you'll also get 2 additional parameters: the resolver parameters as object and the DirectiveNode of the auth directive.
  // In `protect-auth-directive` mode, this function will always get called and you can use these parameters to check if the field has the `@auth` or `@skipAuth` directive

  if (!user) {
    throw new Error(`Unauthenticated!`)
  }
}

Now, configure your plugin based on the mode you wish to use:

Option #1 - protect-all

This mode offers complete protection for the entire API. It protects your entire GraphQL schema by validating the user before executing the request. You can optionally skip auth validation for specific GraphQL fields by using the @skipAuth directive.

To setup this mode, use the following config:

import { envelop } from '@envelop/core'
import { useGenericAuth, ResolveUserFn, ValidateUserFn } from '@envelop/generic-auth'

type UserType = {
  id: string
}
const resolveUserFn: ResolveUserFn<UserType> = async context => {
  /* ... */
}
const validateUser: ValidateUserFn<UserType> = params => {
  /* ... */
}

const getEnveloped = envelop({
  plugins: [
    // ... other plugins ...
    useGenericAuth({
      resolveUserFn,
      validateUser,
      mode: 'protect-all'
    })
  ]
})

Allow unauthenticated access for specific fields using a field directive

By default, we assume that you have the GraphQL directive definition as part of your GraphQL schema (directive @skipAuth on FIELD_DEFINITION).

Then, in your GraphQL schema SDL, you can add @skipAuth directive to your fields, and the default validateUser function will not get called while resolving that specific field:

type Query {
  me: User!
  protectedField: String
  publicField: String @skipAuth
}

You can apply that directive to any GraphQL field definition, not only to root fields.

If you are using a different directive for authentication, you can pass directiveOrExtensionFieldName configuration to customize it.

Allow unauthenticated access for specific fields using a field extension

import { GraphQLObjectType, GraphQLInt } from 'graphql'

const GraphQLQueryType = new GraphQLObjectType({
  name: 'Query',
  fields: {
    foo: {
      type: GraphQLInt,
      resolve: () => 1,
      extensions: {
        skipAuth: true
      }
    }
  }
})

If you want to use a different directive for authentication, you can use the directiveOrExtensionFieldName configuration to customize it.

Option #2 - resolve-only

This mode uses the plugin to inject the authenticated user into the context, and later you can verify it in your resolvers.

import { envelop } from '@envelop/core'
import { useGenericAuth, ResolveUserFn, ValidateUserFn } from '@envelop/generic-auth'

type UserType = {
  id: string
}
const resolveUserFn: ResolveUserFn<UserType> = async context => {
  /* ... */
}
const validateUser: ValidateUserFn<UserType> = async params => {
  /* ... */
}

const getEnveloped = envelop({
  plugins: [
    // ... other plugins ...
    useGenericAuth({
      resolveUserFn,
      validateUser,
      mode: 'resolve-only'
    })
  ]
})

Then, in your resolvers, you can execute the check method based on your needs:

const resolvers = {
  Query: {
    me: async (root, args, context) => {
      await context.validateUser()
      const currentUser = context.currentUser

      return currentUser
    }
  }
}

Option #3 - protect-granular

This mode is similar to option #2, but it uses the @auth SDL directive or auth field extension for protecting specific GraphQL fields.

import { envelop } from '@envelop/core'
import { useGenericAuth, ResolveUserFn, ValidateUserFn } from '@envelop/generic-auth'

type UserType = {
  id: string
}
const resolveUserFn: ResolveUserFn<UserType> = async context => {
  /* ... */
}
const validateUser: ValidateUserFn<UserType> = params => {
  /* ... */
}

const getEnveloped = envelop({
  plugins: [
    // ... other plugins ...
    useGenericAuth({
      resolveUserFn,
      validateUser,
      mode: 'protect-granular'
    })
  ]
})

Protect a field using a field directive

By default, we assume that you have the GraphQL directive definition as part of your GraphQL schema (directive @auth on FIELD_DEFINITION).

Then, in your GraphQL schema SDL, you can add @auth directive to your fields, and the validateUser will get called only while resolving that specific field:

type Query {
  me: User! @auth
  protectedField: String @auth
  # publicField: String
}

You can apply that directive to any GraphQL field definition, not only to root fields.

If you are using a different directive for authentication, you can pass directiveOrExtensionFieldName configuration to customize it.

Protect a field using a field extension

import { GraphQLObjectType, GraphQLInt } from 'graphql'

const GraphQLQueryType = new GraphQLObjectType({
  name: 'Query',
  fields: {
    foo: {
      type: GraphQLInt,
      resolve: () => 1,
      extensions: {
        auth: true
      }
    }
  }
})

If you are using a different field extension for authentication, you can pass directiveOrExtensionFieldName configuration to customize it.

Extend authentication with custom logic

You can also specify a custom validateUser function and get access to a handy object while using the protect-all and protect-granular mode:

import { GraphQLError } from 'graphql'
import { ValidateUserFn } from '@envelop/generic-auth'

const validateUser: ValidateUserFn<UserType> = async ({ user }) => {
  // Now you can use the 3rd parameter to implement custom logic for user validation, with access
  // to the resolver data and information.

  if (!user) {
    return new GraphQLError(`Unauthenticated.`)
  }
}

With a custom directive with arguments

It is possible to add custom parameters to your @auth directive. Here's an example for adding role-aware authentication:

enum Role {
  ADMIN
  MEMBER
}

directive @auth(role: Role!) on FIELD_DEFINITION

Then, you use the directiveNode parameter to check the arguments:

import { ValidateUserFn } from '@envelop/generic-auth'

const validateUser: ValidateUserFn<UserType> = async ({ user, fieldAuthDirectiveNode }) => {
  // Now you can use the fieldAuthDirectiveNode parameter to implement custom logic for user validation, with access
  // to the resolver auth directive arguments.

  if (!user) {
    throw new Error(`Unauthenticated!`)
  }

  const valueNode = fieldAuthDirectiveNode.arguments.find(arg => arg.name.value === 'role').value as EnumValueNode
  const role = valueNode.value

  if (role !== user.role) {
    throw new Error(`No permissions!`)
  }
}

With a custom field extensions

You can use custom field extension to pass data to your validateUser function instead of using a directive. Here's an example for adding role-aware authentication:

import { ValidateUserFn } from '@envelop/generic-auth'

const validateUser: ValidateUserFn<UserType> = async ({ user, fieldAuthExtension }) => {
  // Now you can use the fieldAuthDirectiveNode parameter to implement custom logic for user validation, with access
  // to the resolver auth directive arguments.

  if (!user) {
    throw new Error(`Unauthenticated!`)
  }

  const role = fieldAuthExtension.role

  if (role !== user.role) {
    throw new Error(`No permissions!`)
  }
}

const resolvers = {
  Query: {
    user: {
      me: (_, __, { currentUser }) => currentUser,
      extensions: {
        auth: {
          role: 'USER'
        }
      }
    }
  }
}

With a custom validation function per field

You can also have access to operation variables and context via the executionArgs parameter. This can be useful in conjunction with the fieldAuthExtension parameter to achieve custom per field validation.

import { ValidateUserFn } from '@envelop/generic-auth'

const validateUser: ValidateUserFn<UserType> = async ({ user, executionArgs, fieldAuthExtension }) => {
  if (!user) {
    throw new Error(`Unauthenticated!`)
  }

  // You have access to the object define in the resolver tree, allowing to define any custom logic you want.
  const validate = fieldAuthExtension?.validate
  if (validate) {
    await validate({ user, variables: executionArgs.variableValues, context: executionArgs.contextValue })
  }
}

const resolvers = {
  Query: {
    user: {
      resolve: (_, { userId }) => getUser(userId),
      extensions: {
        auth: {
          validate: ({ user, variables, context }) => {
            // We can now have access to the operation and variables to decide if the user can execute the query
            if (user.id !== variables.userId) {
              throw new Error(`Unauthorized`)
            }
          }
        }
      }
    }
  }
}