How to add custom http header in response from Azure function

Question

I am trying azure function (nodejs) with google authentication from a client side javascript app. I have set up CORS for the correct URL(i.e. http://localhost:8080). But I am still getting the following error:

Credentials flag is 'true', but the 'Access-Control-Allow-Credentials' header is ''. It must be 'true' to allow credentials. Origin 'http://localhost:8080' is therefore not allowed access.

I have tried everywhere on the internet and spent few days to get the answers myself. It seems Azure http response needs to add this Access-Control-Allow-Credentials:true in the header. Is there a way to add custom headers?

Any help will be greatly appreciated.

@Thomas, yes nodejs at server side and javascript fetch at client side. — Sofa Gum
– Sofa Gum, Commented Aug 30, 2016 at 3:22

mathewc · Accepted Answer · 2016-08-31 03:28:11Z

12

In a Node function you can specify additional headers as follows:

module.exports = function (context, req) {
    context.res = {
        status: 200,
        body: "Hello " + req.query.name,
        headers: {
            'Content-Type': 'text/plain',
            'MyCustomHeader': 'Testing'
        }
    };
    context.done();
}

answered Aug 31, 2016 at 3:28

mathewc

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4 Comments

Satjinder Singh Bath Over a year ago

It may not help in this case, I think this error is a preflight http OPTIONS, which means your function would not be called.

Sofa Gum Over a year ago

Yes, I am getting this error in preflight, so my function does not get chance. It was handled by azure infrastructure. Please help me guys, i am real stuck.

Thomas Over a year ago

@SofaGum, how did you configure CORS ? From the azure portal ?

Mehdi Benmoha Over a year ago

this should be top !!

Community · Accepted Answer · 2017-05-23 12:02:26Z

2

I have finally managed to get around the issue. The trick is to remove all the CORS entries from Azure Functions app and handle it directly in your code.

Thanks to the tip shared in another stackoverflow issue regarding azure app service, which worked for azure functions as well.

More details regarding the work around are at:

github issue #620

edited May 23, 2017 at 12:02

CommunityBot

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answered Sep 1, 2016 at 4:34

Satjinder Singh Bath

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1 Comment

Doug Over a year ago

I'm not seeing the desired behavior. When I delete all CORS entries in the App Settings, I can successfully set the "Access-Control-Allow-Credentials" header to "true" in my Azure Functions code. However, in this situation the "Access-Control-Allow-Origin" header is cleared. If I instead use the CORS setting in the App Settings, I can have Access-Control-Allow-Origin set properly, but Access-Control-Allow-Credentials is cleared.

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