Middleware that processes images according to the query string. It is intended to be used in a development setting with the static middleware, but should play well with any middleware further down the stack, even an http proxy, via hijackresponse.
Images are processed using the impro module which implements automatic switching between a number of image libraries based on the requested options.
Important note: This module is intended for development. While impro validates requested image operations, ultimately image data which could be untrusted in such use would be passed directly to various command line tools. In addition, extremely large images represent an attack surface unless restrictions on maximum input and output sizes are configured.
Make sure you have node.js and npm installed, then run:
npm install express-processimage
Query string syntax
Multiple tools can be applied to the same image (separated by
the order is significant). Arguments for the individual tools are
separated by non-URL encoded comma or plus.
http://localhost:1337/myImage.png?pngcrush=-rem,alla http://localhost:1337/myImage.png?pngcrush=-rem+alla http://localhost:1337/myImage.png?optipng=-o7 http://localhost:1337/bigImage.png?resize=400,300&pngquant=128&pngcrush http://localhost:1337/hello.png?setFormat=gif http://localhost:1337/logo.svg?inkscape http://localhost:1337/file.svg?svgfilter=--runScript=makeItBlue.js
Express 3.0 syntax:
var express =processImage =root = '/path/to/my/static/files';;
From this point forward, the resposnes tp GET requests to port 1337 are matched by their Content-Type matched and in the case of an it will be processed by the image pipeline using options specified in query string. The processed output is delivered to the client.
root option is used by node-svgfilter
The response will be be processed under these circumstances:
- If the request has a query string and accepts
- If the response is served with a
express-processimage plays nice with conditional GET. If the
original response has an ETag,
express-processimage will add to it
so the ETag of the processed image never clashes with the original
ETag. That prevents the middleware issuing the original response from
being confused into sending a false positive
304 Not Modified if
express-processimage is turned off or removed from the stack later.
Development with Docker
Build the docker image by running:
$ npm run docker:build
Open the development environment:
$ npm run docker
The above command will place you in a bash shell where the working directory is your express-processimage checkout from your local machine. It is mounted into the container which is based on Ubuntu 14.04 and contains all the required dependencies, and nvm with the latest node 8 version active.
If you need to run the tests against another node version, you just have to change the version using nvm and reinstall your modules.
The environment is configured to resemble our setup on Travis CI as much as possible.
3-clause BSD license -- see the
LICENSE file for details.