Access Google Drive without OAuth2

Google API's indeed work only via OAuth2.0 using a bearer token.

But you can obtain a bearer token from a GCP Service Account's JWT token. Since OAuth via JWT is automatic, no user interaction is involved.

Just create a Service Account, generate a key in JSON format, and "share" your Drive folder with that service account ([email protected]).

Note: a Service Account's key file looks like this ^(redacted):

{
    "type": "service_account",
    "project_id": "<skip>",
    "private_key_id": "<skip>",
    "private_key": "-----BEGIN PRIVATE KEY-----\n <skip> \n-----END PRIVATE KEY-----\n",
    "client_email": "<skip>@<skip>.iam.gserviceaccount.com",
    "client_id": "<skip>",
    "auth_uri": "https://accounts.google.com/o/oauth2/auth",
    "token_uri": "https://oauth2.googleapis.com/token",
    "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
    "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/<skip>%40<skip>.iam.gserviceaccount.com"
}

Example of listing files in Go:

package main

import (
    "fmt"
    "log"

    "golang.org/x/net/context"
    "google.golang.org/api/drive/v3"
    "google.golang.org/api/option"
)

func main() {
    srv, err := drive.NewService(context.Background(), option.WithCredentialsFile("key.json"))
    if err != nil {
        log.Fatal("Unable to access Drive API:", err)
    }
    r, err := srv.Files.List().PageSize(100).Fields("nextPageToken, files").Do()
    if err != nil {
        log.Fatal("Unable to list files:", err)
    }
    fmt.Println("Files:")
    for _, i := range r.Files {
        fmt.Printf("%v (%v) %v %v\n", i.Name, i.Id, i.MimeType, i.Parents)
    }
}

Output:

Files:
Test (1TMx<skip>SoYJ5) application/vnd.google-apps.folder []
Test.txt (1Ele<skip>Fh98n) text/plain [1TMx<skip>SoYJ5]
Test2.txt (3ce9x<skip>lsWds) text/plain [1TMx<skip>SoYJ5]