How to: Add custom JeSuisCharlie header to API responses

A lot of servers have been including a JeSuisCharlie header with their responses. If you haven’t already, try with Charlie Hebdo site itself:

$ curl -I charliehebdo.fr
Date: Mon, 12 Jan 2015 15:56:13 GMT
Content-Type: text/html; charset=iso-8859-1
Content-Length: 221
Connection: keep-alive
Location: http://www.charliehebdo.fr/index.html
Vary: Accept-Encoding
X-Charlie-fr: Je suis toujours Charlie.
X-Charlie-en: I am still Charlie.
X-Charlie-es: Todavia soy Charlie.
X-Charlie-de: Ich bin immer Charlie.
X-Charlie-ro: Inca sunt Charlie.
X-Charlie-cz: Jsem stale Charlie.

I find this to be a great way for us techies to somehow contribute and show support for the ongoing anti-terrorism campaign. So if you feel like doing it here is a quick rundown on how to serve custom headers with your Eve-powered REST API. It is actually a very easy task to accomplish.

Eve provides its own set of callback hooks but since we don’t need fine-grained control (we are good with including the new header with all responses), this time we will leverage Flask’s native callback system instead.

@app.after_request
def after_request(response):
    response.headers.add('X-Charlie', 'Je Suis Charlie.')
    response.headers.add('X-Ahmed', 'Je Suis Ahmed.')
    return response

A simple run script would then look something like:

from eve import Eve
app = Eve()

@app.after_request
def after_request(response):
    response.headers.add('X-Charlie', 'Je Suis Charlie.')
    response.headers.add('X-Ahmed', 'Je Suis Ahmed.')
    return response

if __name__ == '__main__':
    app.run()

All API responses now include the custom headers:

$ curl http://localhost:5000
HTTP/1.0 200 OK
Content-Type: application/json
Content-Length: 141
Server: Eve/0.5 Werkzeug/0.9.6 Python/2.7.8
Date: Mon, 12 Jan 2015 15:39:36 GMT
X-Charlie: Je Suis Charlie.
X-Ahmed: Je Suis Ahmed.

If you want to see it in action try sending a GET request with curl, Postman or similar tool to the Eve demo instance (source). Remember Eve is a Flask subclass so whatever works with Flask generally works with Eve too.

If you want to get in touch, I am @nicolaiarocci on Twitter.