Remote Worker

Separation of Responsibilities

There are several reasons to move some processing out of the main code base for security or performance:

• If there is a security exploit in the image processing library, it will only impact this remote worker
• If you need to send some network requests (e.g., link previewing) to a third party, running those tasks on separate servers to prevent leaking the IP addresses of the main web instances
• If some processing does not rely on the other part of the main code base, then you can move them into the remote worker for better performance

Python Version

This project should always be using the latest version of Python. At the time of this writing, it is 3.10.0. You can install it via pyenv.

We included a pre-commit config to ensure code quality and consistency.

Ubuntu Packages

These packages are required for manipulating images:

sudo apt install libimage-exiftool-perl jhead libmagic-dev

When developing on macOS, you can install those packages with Homebrew:

brew install exiftool jhead

Endpoints

images/prepare_jpeg

Accepts a multipart/form-data request with the following parameters:

- file: the image to process

Two processes are performed on the image:

• Remove GPS info from EXIF metadata
• Adjust the orientation of the image to make it work in browsers that don't support EXIF orientation

images/fit/:box

Accepts a multipart/form-data request with the following parameters:

- file: the image to process

Returns a new image that fits within the given box, and the image's aspect ratio is preserved.

images/rescale_avatar

Accepts a multipart/form-data request with the following parameters:

- file: the image to process

Return a JSON object with the processed versions of the image:

- avatar24: a 24x24 version of the image
- avatar48: a 48x48 version of the image
- avatar73: a 73x73 version of the image
- avatar128: a 128x128 version of the image if the original image is larger than 128x128
- avatar256: a 256x256 version of the image if the original image is larger than 256x256
- avatar512: a 512x512 version of the image if the original image is larger than 512x512

These original image formats are supported:

• JPEG
• PNG
• GIF
• BMP
• TIFF
• WEBP

The output format is always in PNG.

curl example for sending such a request:

curl -X POST -F "file=@/path/to/image.jpg" http://localhost:5000/images/rescale_avatar