NGINX do not pass response header - nginx

Question

I have a java spring application running on port 8080, this app should return a header 'x-auth-token', this app run behind nginx reverse proxy.
The application correctly produce the header, When i request directly to it (bypassing nginx):
http://169.54.76.123:8080
it responds with the header in the set of response headers
but when i make the request through the nginx reverse proxy, the header does not appear
https://169.54.76.123
nginx handles ssl termination.
my nginx conf file
upstream loadbalancer {
server 169.54.76.123:8080 ;
}
server {
listen 169.54.76.123:80;
server_name api.ecom.com;
return 301 https://api.ecom.com$request_uri;
}
server {
listen 169.54.76.123:443 ssl;
keepalive_timeout 70;
server_name api.ecom.com;
ssl_certificate /etc/ssl/api_chained.cert ;
ssl_certificate_key /etc/ssl/api.key ;
ssl_session_cache shared:SSL:10m;
ssl_session_timeout 10m;
ssl_protocols TLSv1 TLSv1.1 TLSv1.2 SSLv3 SSLv2;
ssl_ciphers ALL:!ADH:RC4+RSA:HIGH:!aNULL:!MD5;
charset utf-8;
location / {
proxy_pass http://loadbalancer/$request_uri ;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
}
The question is: Why nGinx do not pass the 'x-auth-token' to the response?
How to include it into the response?
I tried to get the value in a variable, but it seems that nGinx do not have it:
I used $sent_http_x_auth_token and $upstream_htto_x_auth_token but these variables does not contain any values (i think)
I tried adding the header myself using these variables:
add_header x-auth-token $sent_http_x_auth_token; with no success
also tried:
add_header x-auth-token $upstream_http_x_auth_token; with no success either.
also, I tried:
proxy_pass_header x-auth-token;
with no success
What is the problem? How can i debug it?
which part prevents or blocks the 'x-auth-header'? the upstream or the proxy or what?
Thanks for any help

Answer 1

Normally you should have to do anything because nginx does not remove custom headers from the response.
You could use the log_format directive to track the execution of the request, for instance with something like
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent '
'X-Auth-Token: "$sent_http_x_auth_token"';
access_log logs/access.log main;
in you location context.
When you check, do you get a 200 response code that confirms the request succeeded?

Answer 2

The sent_ prefix should not be there.
The correct way to log customer headers is to prefix them with http_ and then write the customer header all lowercase and convert dashes (-) to underscores (_). For example 'Custom-Header' would be http_custom_header
So the correct way to log this is:
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_x_auth_token"';
access_log logs/access.log main;
Also please be aware that if your header contains underscores you will need to explicitly allow this by adding this in your nginx config:
underscores_in_headers on
If you want to test your custom header, you can use curl:
curl -v -H "Custom-Header: any value that you want" http://www.yourdomain.com/path/to/endpoint
The -H will add the header and -v will show you both the request and response headers that are sent