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Example Nginx (> 1.9) configuration for adding cross-origin resource sharing (CORS) support to reverse proxied APIs. Handle error status (4xx, 5xx) and expose headers.
#
# CORS header support
#
# One way to use this is by placing it into a file called "cors_support"
# under your Nginx configuration directory and placing the following
# statement inside your location block(s):
#
# include cors_support;
#
# A limitation to this method is that Nginx doesn't currently send headers
# specified by add_header when the backend returns a 4xx or 5xx status code.
#
# For more information on CORS, please see: http://enable-cors.org/
# Forked from this Gist: https://gist.github.com/michiel/1064640
#
set $cors '';
if ($http_origin ~* 'https?://(localhost|www\.yourdomain\.com|www\.yourotherdomain\.com)') {
set $cors 'true';
}
# always is required to add headers even if response's status is 4xx or 5xx
if ($cors = 'true') {
add_header 'Access-Control-Allow-Origin' "$http_origin" always;
add_header 'Access-Control-Allow-Credentials' 'true' always;
add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, DELETE, OPTIONS' always;
add_header 'Access-Control-Allow-Headers' 'Accept,Authorization,Cache-Control,Content-Type,DNT,If-Modified-Since,Keep-Alive,Origin,User-Agent,X-Mx-ReqToken,X-Requested-With' always;
# required to be able to read Authorization header in frontend
add_header 'Access-Control-Expose-Headers' 'Authorization' always;
}
# 2 if are required, nginx treats each if block as a different context
if ($request_method = 'OPTIONS') {
add_header 'Access-Control-Allow-Origin' "$http_origin";
add_header 'Access-Control-Allow-Credentials' 'true';
add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, DELETE, OPTIONS';
add_header 'Access-Control-Allow-Headers' 'Accept,Authorization,Cache-Control,Content-Type,DNT,If-Modified-Since,Keep-Alive,Origin,User-Agent,X-Mx-ReqToken,X-Requested-With';
return 204;
}
@ValeryDubrava

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@ValeryDubrava ValeryDubrava commented Feb 13, 2020

thanks!

@Longwater1234

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@Longwater1234 Longwater1234 commented Jun 18, 2021

To avoid regex vulnerability, change line 18 to:

if ($http_origin ~* '^https?://(localhost|www\.yourdomain\.com|www\.yourotherdomain\.com)$') {
// ....your code continue
}
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