How to invalidate transformed image after source images are invalidated

enyo

I am compositing an image (result) out of 3 other images (a.webp, b.webp and c.webp) with the overlay (layer) transformation.

When I update one of the source images (a, b or c) with the cld uploader upload command I also send the invalidate flag, but this only invalidates the cache of the source images, not of result .

I think, I could use the explicit method to force regenerating result, but because I need the image in multiple resolutions, I want to avoid that. (I’m also giving a simple example. In my real world scenario, I do this compositing with hundreds of images).

Is there a way I can get this to work efficiently, or do I need to introduce version numbers here?

epasos

The process you have indicated is the recommended way to purge all the CDN copies of the individual overlay source images. 

Overlay Image 1: https://res.cloudinary.com/epasos/image/upload/demo/images/sampleimageA.png

Overlay Image 2: https://res.cloudinary.com/epasos/image/upload/demo/images/SampleImageB.jpg

And in the case of the base image, when you re-upload another copy of the asset (i.e., using the parameters `invalidate=true, overwrite=true, public_id=sampleimage`) - this will purge the CDN copy of the derived versions of the base image. 

Base Image     : https://res.cloudinary.com/epasos/image/upload/demo/images/sampleimage.jpg

In this case, you could replace all the overlay images before you replace the base image so that all newer versions of the assets will be used. And after uploading the base image, you can perform the generation of the final derived asset version, for example:

Derived version of the Base Image: https://res.cloudinary.com/epasos/image/upload/l_demo:images:sampleimageA,g_south/l_demo:images:SampleImageB,c_scale,w_400/demo/images/sampleimage.jpg

As for the CDN invalidation, kindly see - https://support.cloudinary.com/hc/en-us/articles/360001208732-What-URL-conventions-are-invalidated

Hope this helps.

enyo

Just to make sure I understood completely: All dervied versions of a base image will be regenerated, when the base image itself is invalidated?

So in your case: if sampleimage.jpg is invalidated, then the derived version will be invalidated too. BUT if sampleimageA or sampleimageB is updated, then the derived image will not be invalidated, correct?

So I just need to make sure that I replace sampleimageA and sampleimageB before updating (and invalidating) sampleimage.jpg. Is that correct? :)