How can query string parameters be forwarded through a proxy_pass with nginx?

Question

From the proxy_pass documentation:

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.

Since you're using $1 in the target, nginx relies on you to tell it exactly what to pass. You can fix this in two ways. First, stripping the beginning of the uri with a proxy_pass is trivial:

location /service/ {
  # Note the trailing slash on the proxy_pass.
  # It tells nginx to replace /service/ with / when passing the request.
  proxy_pass http://apache/;
}

Or if you want to use the regex location, just include the args:

location ~* ^/service/(.*) {
  proxy_pass http://apache/$1$is_args$args;
}

I use a slightly modified version of kolbyjack's second approach with ~ instead of ~*.

location ~ ^/service/ {
  proxy_pass http://apache/$uri$is_args$args;
}

you have to use rewrite to pass params using proxy_pass here is example I did for angularjs app deployment to s3

S3 Static Website Hosting Route All Paths to Index.html

adopted to your needs would be something like

location /service/ {
    rewrite ^\/service\/(.*) /$1 break;
    proxy_pass http://apache;
}

if you want to end up in http://127.0.0.1:8080/query/params/

if you want to end up in http://127.0.0.1:8080/service/query/params/ you'll need something like

location /service/ {
    rewrite ^\/(.*) /$1 break;
    proxy_pass http://apache;
}

I modified @kolbyjack code to make it work for

http://website1/service
http://website1/service/

with parameters

location ~ ^/service/?(.*) {
    return 301 http://service_url/$1$is_args$args;
}

worked with adding $request_uri:
proxy_pass http://apache/$request_uri;

github gist https://gist.github.com/anjia0532/da4a17f848468de5a374c860b17607e7

#set $token "?"; # deprecated

set $token ""; # declar token is ""(empty str) for original request without args,because $is_args concat any var will be `?`

if ($is_args) { # if the request has args update token to "&"
    set $token "&";
}

location /test {
    set $args "${args}${token}k1=v1&k2=v2"; # update original append custom params with $token
    # if no args $is_args is empty str,else it's "?"
    # http is scheme
    # service is upstream server
    #proxy_pass http://service/$uri$is_args$args; # deprecated remove `/`
    proxy_pass http://service$uri$is_args$args; # proxy pass
}

#http://localhost/test?foo=bar ==> http://service/test?foo=bar&k1=v1&k2=v2

#http://localhost/test/ ==> http://service/test?k1=v1&k2=v2