Using Google API's for one's own account without OAuth - node.js

Question

Specifically, I'd like to use the Gmail API to access my own mail only. Is there a way to do this without OAuth and just an API key and/or client id and secret?
Using an API key like:
require('googleapis').gmail('v1').users.messages.list({ auth: '<KEY>', userId: '<EMAIL>') });
yields the following error:
{ errors:
[ { domain: 'global',
reason: 'required',
message: 'Login Required',
locationType: 'header',
location: 'Authorization' } ],
code: 401,
message: 'Login Required' }
I suppose that message means they want a valid OAuth "Authorization" header. I would do that but I suppose that's not possible without presenting a webpage.

Answer 1

The strict answer to "Is there a way to do this without OAuth and just an API key and/or client id and secret?" is no.
However, you can achieve what you are looking for using OAuth. You simply need to store a Refresh Token, which you can then use any time to request an Auth Token to access your gmail.
In order to get the refresh token, you can either write a simple web app to do a one time auth, or follow the steps here How do I authorise an app (web or installed) without user intervention? (canonical ?) which allows you to do the whole auth flow using the Oauth Playground.

Answer 2

The question is rather old, but the problem is not. For now Google API has an option to create service accounts. I think it suits for everybody who wants "just connect application to its own google workspace" and not to do some actions on users behalf. Google documentation writes about it:
Typically, an application uses a service account when the application uses Google APIs to work with its own data rather than a user's data. For example, an application that uses Google Cloud Datastore for data persistence would use a service account to authenticate its calls to the Google Cloud Datastore API.
Here is the example in Java (there was no JS, but the meaning is clear):
import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.services.sqladmin.SQLAdminScopes;
GoogleCredential credential = GoogleCredential.fromStream(new FileInputStream("MyProject-1234.json"))
.createScoped(Collections.singleton(SQLAdminScopes.SQLSERVICE_ADMIN));
SQLAdmin sqladmin =
new SQLAdmin.Builder(httpTransport, JSON_FACTORY, credential).build();
SQLAdmin.Instances.List instances =
sqladmin.instances().list("exciting-example-123").execute();