Here we describe how to obtain different types of credentials that can be important when working with a Google API:
This can be important for both users and developers:
Note that most users of gargle-using packages do not need to read this and can just enjoy the automatic token flow. This article is for people who have a specific reason to be more proactive about auth.
You will need a Google Cloud Platform (GCP) project to hold your credentials.
Go to the Google Cloud Platform Console:
This console is your general destination for inspecting and modifying your GCP projects.
Create a new project here, if necessary. Otherwise, select the project of interest, if you have more than one.
Enable the relevant APIs(s) for your GCP project.
In the left sidebar, navigate to APIs & Services > Library.
Identify the API of interest. Click Enable.
If you get this wrong, i.e. need to enable more APIs later, you can always come back and do this then.
For some APIs, you won’t be able to do anything interesting with the credentials hosted in your project unless you have also linked a billing account. This is true, for example, for BigQuery and anything that has to do with Maps. This is NOT true, for example, for Drive or Sheets or Gmail.
If your target API requires a billing account, that obviously raises the stakes for how you manage any API keys, OAuth clients, or service account tokens. Plan accordingly.
If you’re new to Google Cloud Platform, you’ll get to enjoy GCP Free Tier. At the time of writing, this means you get $300 credit and no additional billing will happen without your express consent. So there is a low-stress way to experiment with APIs, with a billing account enabled, without putting actual money on the line.
Some APIs accept requests to read public resources, in which case the request can be sent with an API key in lieu of a token. If this is possible, it’s a good idea to expose this workflow in a wrapper package, because then your users can decide to go into a “de-authed” mode. When using the package in a non-interactive or indirect fashion (e.g. a scheduled job on a remote server or via Shiny), it is wonderful to NOT have to manage a token, if the work can be done with an API key instead.
Some APIs aren’t really usable without a token, in which case an API key may not be relevant and you can ignore this section.
Package maintainers might want to build an API key in as a fallback, possibly taking some measures to obfuscate the key and limit its use to your package.
Package users could register an API key for use with a wrapper package. For example, in googledrive, one would use
googledrive::drive_auth_configure() to store a key for use in downstream requests, i.e. after a call to
Most APIs are used to create and modify resources on behalf of the user and these requests must include the user’s token. A regular user will generally need to send an OAuth2 token, which is obtained under the auspices of an OAuth “app” or “client”. This is called three-legged OAuth, where the 3 legs are the app or client, the user, and Google.
The basic steps are described in the Prerequisites section for doing Google OAuth 2.0 for Mobile & Desktop Apps:
Two ways to package this info for use with httr or gargle, both of which require an object of class
In both cases, I suggest you devise a nickname for each OAuth credential and use it as the credential’s name in GCP Console and as the
appname argument to
Package maintainers might want to build this app in as a fallback, possibly taking some measures to obfuscate the client ID and secret and limit its use to your package.
Package users could register this app for use with a wrapper package. For example, in googledrive, one would use
googledrive::drive_auth_configure() to do this:
library(googledrive) # method 1: direct provision client ID and secret google_app <- httr::oauth_app( "my-very-own-google-app", key = "123456789.apps.googleusercontent.com", secret = "abcdefghijklmnopqrstuvwxyz" ) drive_auth_configure(app = google_app) # method 2: provide filepath to JSON containing client ID and secret drive_auth_configure( path = "/path/to/the/JSON/you/downloaded/from/gcp/console.json" ) # now any new OAuth tokens are obtained with the configured app
The most proper way to make authorized requests to an API in a non-interactive context, is to use a service account token. An official overview of service accounts is given in this official documentation by Google. But note that it’s not necessary to understand all of that in order to use a service account token.
~/.R/gargle/, which also holds the default cache folder for OAuth2 tokens managed by gargle.
Authors of wrapper packages can use the symmetric encryption strategy described in Managing tokens securely to use this token on remote servers, such as continuous integration services like Travis-CI.
You could provide the token’s filepath to a wrapper package’s main auth function, e.g.:
Alternatively, you could put the token somewhere (or store its location in an env var) so that it is auto-discovered by the Application Default Credentials search strategy.