JSONProxy

A Python Flask based proxy to turn JSON endpoints into JSONP for cross-domain requests. Meant to be easily deployed to Heroku. Allows for caching and whitelisting.

Similar applications

There are a number of similar applications, but most of them do not whitelist of requests or cache results. Whitelisting is important as a wide-open proxy can easily be abused and cause damage to your own application as well as others. Caching adds a bit of performance boost.

• http://jsonp.jit.su/
• https://github.com/okfn/dataproxy
• https://github.com/greenisus/jsonp-proxy
• https://github.com/mvanholstyn/jsonp-proxy
• https://github.com/clintandrewhall/node-jsonp-proxy
• https://github.com/TomDemeranville/jsonprox

Install and run locally

1. (optional) Create a virtualenv
2. pip install -r requirements.txt
3. Configuration options:
   • Domain whitelist regex
     • Defaults to Amazon's S3: .*s3\.amazonaws\.com$
     • Set: export JSONPROXY_DOMAIN_WL_REGEX='<REGEX>'
   • Path whitelist regex
     • Defaults to anything: .*
     • Set: export JSONPROXY_PATH_WL_REGEX='<REGEX>'
   • Cache time (in minutes)
     • Defaults to 1 minute: 1
     • Set: export JSONPROXY_CACHE=<MINUTES>
4. Run locally: python app.py
5. Go to http://localhost:5000

Deploy on Heroku

For Heroku.

1. Setup and install Heroku command line tools
2. Create Heroku app with whatever name you want: heroku apps:create <APP_NAME>
3. Configuration options:
   • Domain whitelist regex
     • Defaults to Amazon's S3: .*s3\.amazonaws\.com$
     • Set: heroku config:set JSONPROXY_DOMAIN_WL_REGEX='<REGEX>'
   • Path whitelist regex
     • Defaults to anything: .*
     • Set: heroku config:set JSONPROXY_PATH_WL_REGEX='<REGEX>'
   • Cache time (in minutes)
     • Defaults to 1 minute: 1
     • Set: heroku config:set JSONPROXY_CACHE=<MINUTES>
4. Push up code: git push heroku master
5. You can open the app with heroku open
6. Use in your application by making a request like the following. Make sure to encode the proxy url parameter. http://<APP_NAME>.herokuapp.com/proxy?callback=<CALLBACK_NAME>&url=https%3A//http://jsonip.com/

MinnPost example

For our use, we only need access to S3 and a specific bucket that we use for projects, so we set the following:

• export JSONPROXY_DOMAIN_WL_REGEX='.*s3\.amazonaws\.com$'
• export JSONPROXY_PATH_WL_REGEX='^\/data\.minnpost'