How it works
Upload
1) Request to an app for uploading some file(s)
The app just needs to include the Renuo-Upload-JS with an API key to upload files.
2) Delivered Renuo-Upload-JS from the app creates a request with the API key to the image upload app for the credential (policy, signature, etc.)
3) The image upload app generates the credentials if the API key is right and returns them.
4) The form built by the Renuo-Upload-JS creates one request per file to upload it on S3.
5) S3 responds with a status if successful or not.
6) The Renuo-Upload-JS handles the respond status of S3. (todo)
7) The app shows the result.
Part 2 Displaying (& Thumbnails)
8) Visitor requests an image on Cloudfront.
9a) If the image exist, Cloudfront returns the image -> end
9b) If the image doesn't exist on Cloudfront, the request is forwarded to the image processing app.
10) The image processing app requests Renuo-Thumbor with the forwarded request which was adapted and signed to fit Renuo-Thumbor.
11) Renuo-Thumbor manipulates the image and returns it.
12) The image processing server returns the manipulated image to Cloudfront.
13) Cloudfront returns the manipulated image.
The single apps/libraries
Client (Renuo Upload Client)
The Renuo Upload Client is built on top of the Dropzone Library. The upload handles a multicore upload to S3 and provides a user interface. For uploading to S3, a signed policy, signature, etc. is needed. The singing process must be safe and secure so it can not be handled in the JS. For this, Renuo Upload Signing is needed.
The first version of Renuo Upload Client is written in CoffeeScript. The second version will be written in TypeScript.
Renuo Upload Signing
Renuo Upload Signing is a ruby Sinatra app. It is only accessed by the Renuo Upload Client and needed to create a signed policy and the other credentials. It also creates a prefix for every upload, so that nothing can be overwritten by another upload.
Why a ruby Sinatra app?
-Because the first version of the signing part for S3 (policy) was written and tested in ruby.
In a second version it can be rewritten in any language, because the application is that small.
Renuo Thumbs Proxy
Renuo Thumbs Proxy is a python flask app. The application stands between Cloudfront and Renuo-Thumbor. It is needed to generate the correct signed URL for Renuo-Thumbor.
Why a python flask app?
-Because it's a good chance to try something new.
When it wouldn't work well it can be rewritten in any language, because the application is that small.
Renuo Thumbor
Renuo Thumbor is just a configuration application to set up Thumbor, an image manipulation service. (Thumbor is open source and written in python)
Cloudfront
Cloudfront caches all files on S3 which are requested. If a file doesn't exist, the request is forward to the Renuo Thumbs Proxy. It can't be forwarded directly to Renuo-Thumbor, because Renuo-Thumbor requires a signed Request. For this, Renuo Thumbs Proxy is needed.
Amazon S3
There exists one Amazon S3 bucket for all applications that use the upload. Every app has an API key that is a folder in this bucket.