grant-gcloud

Google Cloud Function handler for Grant

var grant = require('grant').gcloud({
  config: {/*configuration - see below*/}, session: {name: '__session', secret: 'grant'}
})

exports.handler = async (req, res) => {
  var {response} = await grant(req, res)
  if (response) {
    res.statusCode = 200
    res.setHeader('content-type', 'application/json')
    res.end(JSON.stringify(response))
  }
}

Also available for AWS, Azure, Vercel

ES Modules and TypeScript

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Configuration

The config key expects your Grant configuration.

Routes

Grant relies on the request path to determine the provider name and any static override being used.

Additionally the prefix specified in your Grant configuration, that defaults to /connect, is used to generate the correct redirect_uri in case it is not configured explicitly.

Default Domain

https://[REGION]-[PROJECT].cloudfunctions.net/[LAMBDA]/connect/google
https://[REGION]-[PROJECT].cloudfunctions.net/[LAMBDA]/connect/google/callback

You have to specify the redirect_uri explicitly because the actual request URL contains the lambda name in the path, but that is never sent to your lambda handler:

{
  "defaults": {
    "origin": "https://[REGION]-[PROJECT].cloudfunctions.net"
  },
  "google": {
    "redirect_uri": "https://[REGION]-[PROJECT].cloudfunctions.net/[LAMBDA]/connect/google/callback"
  }
}

Firebase Hosting

In case you have the following rewrites configuration that proxy all requests to your grant handler:

{
  "hosting": {
    ...
    "rewrites": [
      {
        "source": "**",
        "function": "grant"
      }
    ]
  }
}

https://[PROJECT].firebaseapp.com/connect/google
https://[PROJECT].firebaseapp.com/connect/google/callback

{
  "defaults": {
    "origin": "https://[PROJECT].firebaseapp.com"
  },
  "google": {}
}

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Local Routes

When running locally the following routes can be used:

http://localhost:3000/connect/google
http://localhost:3000/connect/google/callback

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Session

The session key expects your session configuration:

Option	Description
name	Cookie name, defaults to grant, it have to be set to __session for Firebase Hosting!
secret	Cookie secret, required
cookie	cookie options, defaults to {path: '/', httpOnly: true, secure: false, maxAge: null}
store	External session store implementation

NOTE:

• The default cookie store is used unless you specify a store implementation!
• Using the default cookie store may leak private data!
• Implementing an external session store is recommended for production deployments!

Example session store implementation using Firebase:

var request = require('request-compose').client

var path = process.env.FIREBASE_PATH
var auth = process.env.FIREBASE_AUTH

module.exports = {
  get: async (sid) => {
    var {body} = await request({
      method: 'GET', url: `${path}/${sid}.json`, qs: {auth},
    })
    return body
  },
  set: async (sid, json) => {
    await request({
      method: 'PATCH', url: `${path}/${sid}.json`, qs: {auth}, json,
    })
  },
  remove: async (sid) => {
    await request({
      method: 'DELETE', url: `${path}/${sid}.json`, qs: {auth},
    })
  },
}

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Handler

The Google Cloud Funtion handler for Grant accepts:

Argument	Type	Description
req	required	The request object
res	required	The response object
state	optional	Dynamic State object {dynamic: {..Grant configuration..}}

The Google Cloud Funtion handler for Grant returns:

Parameter	Availability	Description
session	Always	The session store instance, get, set and remove methods can be used to manage the Grant session
redirect	On redirect only	HTTP redirect controlled by Grant, it is set to true when Grant is going to handle the redirect internally
response	Based on transport	The response data, available for transport-state and transport-session only

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Examples

Example	Session	Callback λ
transport-state	Cookie Store	✕
transport-querystring	Cookie Store	✓
transport-session	Firebase Session Store	✓
dynamic-state	Firebase Session Store	✕

Different session store types were used for example purposes only.

Configuration

All variables at the top of the Makefile with value set to ... have to be configured:

• project - Project ID

• account.json - Project Service Account Credentials

• firebase_path - Firebase path of your database, required for transport-session and dynamic-state examples

https://[project].firebaseio.com/[prefix]

• firebase_auth - Firebase auth key of your database, required for transport-session and dynamic-state examples

{
  "rules": {
    ".read": "auth == '[key]'",
    ".write": "auth == '[key]'"
  }
}

All variables can be passed as arguments to make as well:

make plan example=transport-querystring ...

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Develop

# build example locally
make build-dev
# run example locally
make run-dev

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Deploy

# build Grant lambda for deployment
make build-grant
# build callback lambda for transport-querystring and transport-session examples
make build-callback
# execute only once
make init
# plan before every deployment
make plan
# apply plan for deployment
make apply
# cleanup resources
make destroy

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