Nginx pass_proxy with variables - nginx

Question

I'm having trouble making nginx proxy an url with variable to a service within kubernetes.
Url looks like this:
http://localhost/user?username=Dave
I expect this url to take me to a subpage /user, which will read ?username=Dave and then fetch data from a database. However this takes me to the home page of the application(/ instead of /user) and does not read the variable even though url includes /user?username=Dave.
My current nginx config file looks like this:
server {
listen 0.0.0.0:80;
server_name localhost;
location / {
proxy_pass http://${FLASK_APP}:8080/;
}
location /user {
proxy_pass http://${GO_APP}:8000/;
}
}
I have read that location /user will match the url I'm passing. What is wrong with it? Or do I need to add something to proxy_pass http://${GO_APP}:8000/; or location /user?

Answer 1

As noted in the comments, the issue arises because you are using a variable in the proxy_pass target. As also noted in the comments, this question is related. As the answer referencing the docs states:
A special case is using variables in the proxy_pass statement: The
requested URL is not used and you are fully responsible to construct
the target URL yourself.
This means that you either need to use a static proxy_pass target, such as
// note that I added the forward slash
location /user/ {
proxy_pass http://destination:8000/;
}
Or as an alternative, I believe you can do it this way also
location /user/ {
proxy_pass http://${GO_APP}:8000/user$is_args$args;
}