Send It Once

Simple Google App Engine application for creating single-use file downloads.

How To Use This

1. Deploy the app.yaml at the root of this project to your App Engine project
2. Create an App Engine project and enable the default GCS bucket.
3. Create a "downloads" directory in the GCS bucket.
4. Upload the file you want to deliver into the downloads directory.
5. Create a key file named the same as the above file with ".key.txt" added to the end of the file name. (see below for format of this file)
6. Upload this key file into the downloads directory.

Key File Format

Key files are plain text files in this form:

key|ttl

• key: Any string without pipe characters.
• ttl: Time in seconds that the download will be valid for after it is first used.

Accessing Download Links

Download links are in this form:

https://APP_ID.appspot.com/downloads/filename?key=key

Replace APP_ID with the application ID of your Google Cloud Platform project.

Once a download link is used for the first time, the key file in GCS will be rewritten with a expiration timestamp in place of the TTL value.

Example

In default GCS bucket:

downloads
├── some_file.jpg
└── some_file.jpg.key.txt

Contents of some_file.jpg.key.txt:

c17a852292ae482eaf2cd4decfbf23d1|900

This link will be active for 15 minutes after it is first used:

https://APP_ID.appspot.com/download/some_file.jpg?key=c17a852292ae482eaf2cd4decfbf23d1