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asp.net-coreamazon-s3corsangular5amazon-cloudfront

CORS issue: Angular 5 on AWS S3 & Cloudfront and .net core webapi on IIS10 EC 2 windows server 2019

I am getting following error while accessing Angular app through browser (chrome/Edge/Firefox/Opera). API request works on direct calls from well through Postman/Fiddler.

So i think there something between Cloudfront and EC2 calls and CORS policy

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Following is my set up.

Angular Setup:

  • S3 Bucket with Public access Policy
  • Cloudfront with Behavior whitelisting Headers

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.netcore web api setup:

  • EC 2 instance with Windows Server 2019
  • IIS 10 website with following httpresponse headers added SSL implemented enter image description here
  • As required I have addred CORS policy in .net core application as follows
    services.AddCors(options =>
            {
                options.AddPolicy("EnableCORS", builder =>
                {
                    builder.AllowAnyOrigin()
                        .AllowAnyHeader()
                        .AllowAnyMethod()
                        .AllowCredentials();
                });
            });

added CORS middleware

     app.UseCors("EnableCORS");

Have added required Annotation over APi Controllers

     [EnableCors("EnableCORS")]

Not sure what am i missing along this setup.

Solution

  • Finally got it worked with few changes to my setup of CORS in .netcore code and IIS. Following are the changes.

    • Upgraded my app from .netcore 2.2 to 3.0
    • I changed CORS Origion policy from AllowAnyOrigion() to WithOrigins("https://xxx.xxxx.com")
    • Removed IIS CORS module from IIS 10 web site.
    • Removed All CORS headers from IIS HTTP Response Headers

    to sum it up instead of trying to manage CORS headers from IIS, I left it to Kestral.

    Still not sure what was the exact issue.