multipart-upload-proxy

README

Multipart Upload Proxy (Golang)

There are many tools to help you resize images when fetching resources from your online storage. However, sometimes you want to resize large images during an upload automatically instead. Especially if you don't have control over the software that is supposed to process the uploaded image, for example because it's open source and the contributors don't think resizing should be a feature, getting the feature into the existing code base can be difficult.

This is where the multipart upload proxy comes into play. You can route all multipart file uploads to the proxy and it will digest and resize images to the size you want, finally relaying the same payload with all headers and just a compressed file to the endpoint that saves the file.

The proxy is written in Golang and packaged in a small and safe Alpine container. If you want to develop, run or compile the binary, please be aware that the image resizing uses the bimg library, which requires a linux vips environment. If you're in Windows, usage of WSL is highly recommended.

Usage

Use the docker container like below. It uses the Github docker registry with signed docker containers. Use environmental variables to adjust settings. The container exposes port 6743 via HTTP.

docker run --rm -p 6743:6743 --name=multipart-upload-proxy ghcr.io/jamescullum/multipart-upload-proxy:main

In docker compose, you can use it like this (if you only want it to be exposed within the docker network).

  upload-proxy:
    container_name: upload_proxy
    image: ghcr.io/jamescullum/multipart-upload-proxy:main
    environment:
      - IMG_MAX_WIDTH=1920
      - IMG_MAX_HEIGHT=1080
      - FORWARD_DESTINATION=http://immich-server:3001/api/assets
      - FILE_UPLOAD_FIELD=assetData
      - LISTEN_PATH=/api/assets
    restart: always

If you use existing software, it might be needed to intercept incoming connections and redirect them to this proxy. You can do this via Cloudflare tunnels or via a front-facing reverse proxy/webserver.

Environment variables

Variable name	Default	Comment
IMG_MAX_WIDTH	1920	Pixels, keeps aspect ratio
IMG_MAX_HEIGHT	1080	Pixels, keeps aspect ratio
UPLOAD_MAX_SIZE	104857600	Maximum form size in bytes
IMG_MAX_PIXELS	2073600	If the images width*height (in pixels) doesn't exceed this value, don't resize
FORWARD_DESTINATION	https://httpbin.org/post	Where should the result be sent to
FILE_UPLOAD_FIELD	assetData	Name of the file field to potentially resize
LISTEN_PATH	/api/assets	Path used to process file uploads