Create README.md

README.md

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+Use Cloudflare Workers to turn your Google Drive into S3 object storage at no extra cost.
+
+## About
+This is a Workers script that converts the Google Drive API into an S3-compatible API. Turn your Google Drive into object storage at no extra cost!
+
+### Does it work with the free Workers plan?
+Signature verification uses the native Web Crypto API, and exceeding the 10ms CPU time limit is not normal usage. It also leverages JavaScript streams to handle large files.
+However, this means that features such as hash verification are not implemented. This is because the memory limitations of Workers make it impossible to expand the entire uploaded file into memory.
+
+### Does this violate the Google Terms of Service?
+We believe that it does not violate the Terms of Service as long as you do not upload illegal content such as CSAM.
+For the sake of your Google account, we strongly recommend using this in an environment where only you can upload.
+
+
+## How to Deploy
+
+### 1. Prepare a Google Drive API Refresh Token
+You will need to use rclone to obtain your Google API credentials and a Google Drive API refresh token.
+Follow the rclone documentation to configure the client.  
+https://rclone.org/drive/#making-your-own-client-id
+
+> [!NOTE]
+> When your Google API client is in "Testing" mode, the refresh token will expire after a certain period of time, so if you need to use it for a long period of time, be sure to switch the mode before authenticating with rclone.
+> 
+> You can complete the OAuth flow by skipping the very scary confirmation screen without submitting your app for validation.
+
+Once complete, obtain the path to your rclone configuration file using `rclone config file`, read the configuration file, and note the following values:
+
+```
+[my-remote]
+type = drive
+# Use as GOOGLE_CLIENT_ID
+client_id = myud.apps.googleusercontent.com
+# Use as GOOGLE_CLIENT_SECRET
+client_secret = SUPER_SECRET_TOKEN
+scope = drive
+token = {
+  "access_token":"SECRET_ACCESS_TOKEN",
+  "token_type":"Bearer",
+  # ↓ Use this value as GOOGLE_REFRESH_TOKEN.
+  "refresh_token":"SECRET_REFRESH_TOKEN",
+  "expiry":"2026-01-08T12:37:09.064662+09:00",
+  "expires_in":3599
+}
+
+```
+
+### 2. Configure Cloudflare
+From the Cloudflare dashboard, create two KV databases.
+Create a fork of this repository, edit `wrangler.json`, and modify the binding to the ID of your KV database.
+
+Once complete, deploy Workers by running the following command:
+```bash
+wrangler deploy
+```
+
+### 3. Configure Secrets
+Follow the documentation to configure the following secrets:  
+https://developers.cloudflare.com/workers/configuration/secrets/#via-the-dashboard
+
+| Key | Description |
+| :--- | :--- |
+| `ACCESS_KEY` | Any access key used by the S3 client. |
+| `SECRET_KEY` | A secure secret key used by the S3 client. |
+| `REGION` | The region used by the S3 client. |
+| `GOOGLE_CLIENT_ID`,  `GOOGLE_CLIENT_SECRET`,   `GOOGLE_REFRESH_TOKEN` | Google API credentials obtained from rclone. |
+| `ALLOWED_BUCKETS` | Set the buckets allowed, separated by `,`. A directory with the bucket name will be created directly under Google Drive. |
+
+
+### 4. CORS Configuration
+If you need to configure CORS, set up your own domain for Workers and use Cloudflare's Response Header Transform Rules to add the necessary headers.  
+https://developers.cloudflare.com/rules/transform/response-header-modification/