google-service-account

> Make authenticated requests using a [Google service account][gsa].

This maintains an active Google service account token, allowing you to make server-to-server requests. It will automatically re-fetch a new token if a previous one expires.

To make a valid connection, you just attach an Authorization property to your outgoing request's headers object. This module returns that object.

Install

``sh
$ npm install --save google-service-account
`

Use

> error handling omitted

`js
var request = require("request")

var authorize = require("google-service-account")({
keyFile: "path/to/keyfile.json"
})

authorize(function (err, headers) {
request({
method: "GET",
uri: "https://www.googleapis.com/pubsub/v1beta1/subscriptions",
headers: headers
}, function () {
// Request callback.
})
})
`

Each time you invoke authorize(), a new token may be fetched if necessary. Be sure to call it each time you make an outgoing request.

If the example above looked a little verbose for you, you may also use the authorize function for its extending functionality:

`js
authorize({
method: "GET",
uri: "https://www.googleapis.com/pubsub/v1beta1/subscriptions"
}, function (err, requestObject) {
request(requestObject, function () {
// Request callback.
})
})
`

If even that gets tiresome, you can always write up a quick helper for your app:

`js
function makeAuthorizedRequest(opts, cb) {
authorize(opts, function (err, requestObject) {
request(requestObject, cb)
})
}
// ...later...
makeAuthorizedRequest({
method: "GET",
uri: "https://www.googleapis.com/pubsub/v1beta1/subscriptions"
}, function(err, response) {
// Request callback.
})
`

API

$3

#### options

One of the following is required:

##### options.credentials
- Type: Object

The contents of a JSON key file downloaded from the [Google Developers Console][console].

##### options.keyFile
- Type: String

Path to a JSON key file downloaded from the [Google Developers Console][console].

##### options.scopes
- Type: Array

The scopes your request requires.

$3


- Type: Function

Invoke this method every time you need a valid token. It will handle requesting a new token if necessary, and will return it to your callback as part of an HTTP request headers object:
`
{
headers: {
Authorization: "..token.."
}
}
`

#### options
- (optional)
- Type: Object

The object you pass in here will be extended with the token object in the format above.

#### callback
- Type: Function

The callback function receives a HTTP request headers` object, containing a valid token.

$3

Invoke this method to get the credentials object, containing the client_email, client_id, etc.

$3

Invoke this method to get only the value of a token.

[console]: https://console.developers.google.com
[gsa]: https://developers.google.com/accounts/docs/OAuth2ServiceAccount