26

I'd like to add a parameter in the URL in a proxy pass. For example, I want to add an apiKey : &apiKey=tiger
http://mywebsite.com/oneapi?field=22 ---> https://api.somewhere.com/?field=22&apiKey=tiger Do you know a solution ?

Thank's a lot, Gilles.

server {
      listen   80;
      server_name  mywebsite.com;
      location /oneapi{
      proxy_pass         https://api.somewhere.com/;
      }
    }
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5 Answers 5

Reset to default
35 
location = /oneapi {
  set $args $args&apiKey=tiger;
  proxy_pass https://api.somewhere.com;
}
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5 Comments

If $args is empty you set $args to ?&apiKey=tiger. It's not right.
In facts, I validated too fast your answer and the edited solution worked. In the question $args isn't empty => ?field=22&apiKey=tiger
This does not appear to work when using a location /somepath block (no equals sign). I had to use rewrite ^(.*)$ $1?$args&myParam=value break; instead at the same spot.
great solution, but see my solution if you want it to work when $args is empty
This is not cleanest way. Please take a look mine.
17

The other answers do not work if $args is empty.

This also works if $args is empty.

location /oneapi {
  set $delimeter "";

  if ($is_args) {
    set $delimeter "&";
  }

  set $args "$args${delimeter}apiKey=tiger";

  proxy_pass https://api.somewhere.com/;
}
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2 Comments

Thanks alot :D :D
This is not cleanest way. Please take a look mine.
4

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
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8 Comments

the answer would be better if you explained the code and the reason for it.
@ADyson sorry, my english is not very good , but i am working on it. I will improve my answer.
Close, but here when $args is empty, http://localhost/test/ will actually redirect to http://service/test??k1=v1&k2=v2 (two integorrations signs), which seems to be caused by nginx turning $is_args to ? when concatenating to another string, even if empty. Removing $is_args from the final statement in turn will cause $args to lack the preceding token when not empty.
if $args is empty,the $token is ? ,so ` set $args "${args}${token}k1=v1&k2=v2"` you'll get empty str+?+custom params. if $args is not empty ,the $token is &, the L8 code is ?old args+&+custom params.
@Mahn the nginx's doc nginx.org/en/docs/http/ngx_http_core_module.html#var_is_args ?” if a request line has arguments, or an empty string otherwise
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3

Here's a way to add a paramater in nginx when it's unknown whether the original URL had arguments or not (i.e. when you have to account for both ? and &):

location /oneapi {
    set $pretoken "";
    set $posttoken "?";

    if ($is_args) {
        set $pretoken "?";
        set $posttoken "&";
    }

    # Replace apiKey=tiger with your variable here
    set $args "${pretoken}${args}${posttoken}apiKey=tiger"; 

    # Optional: replace proxy_pass with return 302 for redirects
    proxy_pass https://api.somewhere.com$uri$args; 
}
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Comments

1

For someone get here. Thanks for https://serverfault.com/questions/912090/how-to-add-parameter-to-nginx-query-string-during-redirect

The cleanest way on 2021 is:

rewrite ^ https://api.somewhere.com$uri?apiKey=tiger permanent;

If a replacement string includes the new request arguments, the previous request arguments are appended after them

proxy_pass way


upstream api {
    server api.somewhere.com;
}

location /oneapi {
    rewrite ^/oneapi/?(.*) /$1?apiKey=tiger break;
    proxy_pass https://api$uri$is_args$args;
}
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3 Comments

Redirect & proxy are two different things. Try googling "redirect vs proxy".
@Lukman They can be used together. Try googling "rewrite proxy_pass together".
This is the correct and most flexible way in terms of query parameters

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