Nginx image processing server with OpenResty and Lua

I have done something similar at a little scale. At small load, it is great. The larger you get, real problems start to arise.<p>The bottleneck with this implementation is ImageMagick. ImageMagick leaks a lot of memory and is generally very inefficient with resizing operations. GraphicsMagick is not much better. Under high load, this will crush your CPUs and max out your Nginx threads much faster than it is worth. You will almost definitely need to use something like OpenCV on the GPU for this to scale.<p>Although caching is referenced briefly in this article, it is crucial for this system to work. A good CDN with fast invalidation and a low eviction rate would be ideal.

I&#x27;ve probably done this ten times in ten different ways over the years. Most recently with ~150 lines of Go via nginx proxy_pass (or fastcgi_pass). I needed to be able to control how to resize images while maintaining aspect ratio on a fixed size canvas. The first request for an image is disappointingly slow for larger images, but it&#x27;s not terrible. Writing out the generated images to a cache directory and using try_files, so subsequent requests are static, is definitely key.

Did it with the perl module in Nginx with imagemagick.<p>Much more powerful than their built in image handling which uses the ancient and no longer updated GD library.

I highly recommend <a href="http://www.imgix.com/" rel="nofollow">http:&#x2F;&#x2F;www.imgix.com&#x2F;</a>

I can recommend thumbor: <a href="https://github.com/globocom/thumbor" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;globocom&#x2F;thumbor</a>

Since disk space is not much of problem this day, why don&#x27;t we just pre-process the images? I know this only applies if you know in advance which sizes you want, but do you really need like 20 different sizes of an image?

Since author is talking about security a bit, I&#x27;ll add. Be careful, if there is a bug somewhere in imagemagick or it runs out of memory, it could easily take down an entire worker process and abort every connection there.

Has anybody done something like this with support for uploading and resizing images via a REST API with OpenResty. Do you know of any good examples or tutorials for that or upload support in general?

for true hipster web scale power, one must use node.js <a href="https://github.com/saml/nodejs-resize-image" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;saml&#x2F;nodejs-resize-image</a>

...or you could just use Pixtulate (<a href="http://www.pixtulate.com" rel="nofollow">http:&#x2F;&#x2F;www.pixtulate.com</a>)

Thanks for posting this. Do those Lua scripts run concurrently in any way?