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simo avatar Server

How to proxy the full url at nginx config?

ve flag
simo

I need to proxy locations /v1/api/ to another url as:

location /api/v1/ {
        proxy_pass http://frontend-api.preprod.my-app.com/api/v1/;
    }

however, at the mainstream, only the slug is received:

"GET /api/v1/ HTTP/1.1" 404 209 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/96.0.4664.110 Safari/537.36"

because the upstream is configured to the specific domain frontend-api.preprod.my-app.com:

server {
    listen 80;
    server_name frontend-api.preprod.my-app.com;

   location / {
      root /var/www/frontend_api/current/public;

      # Turn on Passenger
      passenger_enabled on;
      passenger_ruby /home/deploy/.rvm/gems/ruby-2.7.2/wrappers/ruby;
    }

}

the final result is 404, How would configure proxy_pass at the proxy server to send the host as well, so that the receiving server receives the full url instead of just the /api/v1/ ?

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us flag
Tero Kilkanen

nginx documentation explains the behavior:

If the proxy_pass directive is specified with a URI, then when a request is passed to the server, the part of a normalized request URI matching the location is replaced by a URI specified in the directive:

In your case, it means that the request URI is replaced by the /api/v1/ URI specified in your proxy_pass directive.

If you want the URI to be passed as-is, then you need to do:

location /api/v1/ {
    proxy_pass http://frontend-api.preprod.example.com;
}

In this case, nginx uses the URI from the original request with the proxy_pass destination, as described by:

If proxy_pass is specified without a URI, the request URI is passed to the server in the same form as sent by a client when the original request is processed, or the full normalized request URI is passed when processing the changed URI:

If you want to replace part of the request URI with different part, you need to use regular expression capture:

location ~ ^/source/path/(.*) {
    proxy_pass http://example.com/destination/path/$1;
}

Edit:

To get the domain name of the original request passed to the upstream, one needs to set the Host HTTP header for the upstream request:

proxy_set_header Host       $host;

It is often useful to pass also the IP address of the visitor via header:

proxy_set_header X-Forwarded-For $remote_addr;
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simo avatar
ve flag
simo
I tried `proxy_pass http://frontend-api.preprod.example.com;` but at the other side, I still get the same result. I don't have an issue with passing the slug, the issue is that the base url is not passed, only`/api/v1/` is seen at the receiving server, not `http://frontend-api.preprod.example.com/api/v1/`
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us flag
Tero Kilkanen
You cannot pass the full URL as URI to the request to the backend. To get the host name, you need to use HTTP headers. I added an example to the answer.
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simo avatar
ve flag
simo
Thanks, I tried setting the Host header to $host, however, after that, I can't see the logs coming in the access.log of the receiver nginx!
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us flag
Tero Kilkanen
Then your virtual host name setting in receiver nginx is not correct.
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simo avatar
ve flag
simo
Thank you, there were an issue..
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