purplecandy/b2-video-sharing-example

Backblaze B2 transcoder proof-of-concept web application

Backblaze B2 Video Sharing Example

The Backblaze B2 Video Sharing Example comprises a lightweight Flask worker app and a web app implemented with Django and JavaScript. Together, they implement 'CatTube', a simple video sharing site.

User Experience

• Users upload videos from their browser via the web app.

• Once the video is uploaded, a JavaScript front end in the browser polls an API at the web app until the transcoded version is available.

• On receiving the video, the web app:

  • Uploads it to B2 via the Backblaze S3 Compatible API.

  • Saves a record with the B2 object key to its local database.

  • POSTs a JSON notification to the worker app containing the video's B2 object key and a callback URL.

• The worker app:

  • Downloads the video from B2 to local storage.

  • Uses ffmpeg to transcode the video.

  • Uploads the transcoded video to B2.

  • POSTs a JSON notification back to the web app containing the names of the original file and the transcoded version.

• The web app updates the video's database record with the name of the transcoded file.

• The next call from the JavaScript front end will return with the name of the transcoded video, signalling that the transcoding operation is complete. The browser shows the transcoded video, ready for viewing.

Prerequisites

• Python 3.9.2 (other Python versions may work) and pip
• ffmpeg (Worker only)

Installation

You may deploy both apps on the same host, listening on different ports, or on two different hosts. If the apps are running on different hosts, you must ensure that there is connectivity on the ports you are using.

Clone this repository onto each host. On each host, cd into the local repository directory, then use pip install to install dependencies for the components as required:

For the web application:

cd web-application
pip install -r requirements.txt
cd ..

For the worker:

cd worker
pip install -r requirements.txt
cd ..

Configuration

Web Application

Create a .env file in the web-application directory or set environment variables with your configuration:

AWS_S3_REGION_NAME="<for example: us-west-001>"
AWS_ACCESS_KEY_ID="<your B2 application key ID>"
AWS_SECRET_ACCESS_KEY="<your B2 application key>"
AWS_PRIVATE_BUCKET_NAME="<your private B2 bucket, for uploaded videos>"
AWS_STORAGE_BUCKET_NAME="<your public B2 bucket, for static web assets>"
TRANSCODER_WEBHOOK="<the API endpoint for the transcoder worker, e.g. http://1.2.3.4:5678/videos>"

Edit cattube/settings.py and add the domain name of your application server to ALLOWED_HOSTS. For example, if you were running the sample at videos.example.com you would use

ALLOWED_HOSTS = ['videos.example.com']

Note that ALLOWED_HOSTS is a list of strings - the square brackets are required.

From the web-application directory, run the usual commands to initialize a Django application:

python manage.py migrate
python manage.py createsuperuser
python manage.py collectstatic

Worker

Create a .env file in the worker directory or set environment variables with your configuration:

B2_ENDPOINT_URL="<for example: https://s3.us-west-001.backblazeb2.com>"
B2_APPLICATION_KEY_ID="<your B2 application key ID>"
B2_APPLICATION_KEY="<your B2 application key>"
BUCKET_NAME="<your private B2 bucket, for uploaded videos>"

Run the Worker App

Use flask run to run the app in the Flask development server.

You may change the interface and port to which the worker app binds with the -h/--host and -p/--port options. For example, to listen on the standard HTTP port on all interfaces, you would use:

flask run -h 0.0.0.0 -p 80

Run the Web App

To start the development server:

python manage.py runserver

You may provide the runserver command with the interface and port to which the web app should bind. For example, to listen on the standard HTTP port on all interfaces, you would use:

python manage.py runserver 0.0.0.0:80

Caveats

Note that this is an example system! To run a similar system in production, you would need to make several changes, including:

• Using a message queue such as Apache Kafka or RabbitMQ rather than HTTP POST notifications.
• Running the apps from a WSGI server such as Green Unicorn or Apache Web Server with mod_wsgi.

Feel free to fork this repository and submit a pull request if you make an interesting change!

The web application was originally forked from the excellent simple-s3-setup by sibtc.