Google Cloud Storage authentication without key file in Node.js

Google has instructions on how to authenticate with a service account, but the current documentation only explains how to do it with a key file. Is there any way to authenticate using the more familiar method of using project environment variables? Yes!

The recommended way to authenticate

The Google Cloud docs recommend downloading your service account key as a JSON file and either setting the file path in a system-level environment variable or passing the filename into the instantiation of the Google Cloud class you are using.

However rather than assuming a key file will exist in some location on the server, I think it is a cleaner solution to set the credentials as environment variables and explicitly reference them in the code.

Not to mention I couldn't get this "recommended" method to work 🙄. I was getting the following errors:

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1ERROR: Error: Could not load the default credentials. Browse to https://cloud.google.com/docs/authentication/getting-started for more information.

The alternative way to authenticate

Thankfully the alternative is quite simple (although not well documented):

Open the service account JSON credentials file and grab the following: project_id, client_email, and private_key.

Set them as project environment variables (I'm using Next.js's .env.local file), and instantiate the Storage class as follows:

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1const {Storage} = require('@google-cloud/storage');
2const storage = new Storage({
3    projectId: project_id
4    credentials: {
5        client_email,
6        private_key,
7    }
8});

Note that projectId is the only field name that is camelCase.

I tested it with the getBuckets example, and voila! Successful API call 🎉.

Tested with Node.js 14.15.0 and @google-cloud/storage@5.5.0.