Header names after september 30 (Load balancers)

[Santiago Del Valle]

We got this email

After September 30, HTTP(S) Load Balancers will convert HTTP/1.1 header names to lowercase in the request and response directions; header values will not be affected.

As header names are case-insensitive, this change will not affect clients and servers that follow the HTTP/1.1 specification (including all popular web browsers and open source servers). Similarly, as HTTP/2 and QUIC protocols already require lowercase header names, traffic arriving at load balancers over these protocols will not be affected. However, we recommend testing projects that use custom clients or servers prior to the rollout to ensure minimal impact.

However I do not understand if this will affect headers injected by google, like "HTTP_X_APPENGINE_COUNTRY" which we use on our project, is this going to change or will it remain unaffected?

[Nicolas (Google Cloud Platform Support)]

Hi Santiago,

Headers injected by Google will be lower case as "Load Balancers will convert HTTP/1.1 header names to lowercase in the request and response directions".

From the browser’s point of view it would not matter as browsers don’t look at the field name to see if they are upper or lower case. 

That being said if your application is somehow manipulating or using that value please keep in mind that it would be good practice to have the application handle them as case insensitive.

[Carl Smith]

You can test to see how your application handles lowercase by passing this header through also.

x-goog-downcase-all-headers: test

This will make all of the headers lowercase

[Joshua Smith]

Wait. What?

Are you saying this bit of server code isn’t going to work after September 30?

class CountryHandler(webapp2.RequestHandler):

  def get(self):

    self.response.headers["Content-Type"] = "text/plain"

    self.response.out.write(self.request.headers["X-AppEngine-Country"])

Or is the issue only on the client side?

Also, I didn’t get that email. I get emails all the time from google about stuff they are deprecating (the most recent being a stern warning that I need to stop using the lovely “Launcher” app and instead use the terrible command-line interface; a development about which I am not at all pleased). Why wouldn’t I have gotten this one?

-Joshua

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[David Mattatall]

Does this only affect "google injected headers" or all headers that traverse through the google load balancer?

Where is the official google change release document? 

[Elliott (Cloud Platform Support)]

Hello,

I was able to find some information you may need in the following post. I hope this will help. Those who were believed to benefit from this email, although not thoroughly, would have gotten this email.