Is it possible to use variable with redirect code in Nginx configuration?

Question

In my Nginx config I have redirect rules like this:

map $uri $target {
    '/test123' 'https://www.somedomain.com/test456';
}
map $uri $target_code {
    '/test123' 301;
}
server {
    listen 80 default;

    if ($target_code = 301) {
        return 301 $target;
    }
    if ($target_code = 302) {
        return 302 $target;
    }
}

and it works well. But regarding of If is evil

I want make statement like this:

server {
    listen 80 default;

    return $target_code $target;
}

But during the restart, Nginx returns error nginx: [emerg] invalid return code "$target_code" in /etc/nginx/nginx.conf

Is any possibility to use variable in that way? Or maybe is other way to make it without any if statements?

Your linked document only relates to the use of `if` within a `location` context. And if you use a `map` you need a conditional statement to implement the `return`, and in vanilla Nginx that requires an `if` statement. — Richard Smith, Dec 02 '18 at 10:47
As far as I know only redirect URL or response body in `return` directive can contain variables. I think there is no way to get rid of `if` statements with this configuration. — Ivan Shatsky, Dec 02 '18 at 12:09

score 0 · Answer 1 · answered Jan 15 '21 at 23:16

From what I can see this that is not possible. What follows is the relevant part of the code:

    ret->status = ngx_atoi(p, value[1].len);

    if (ret->status == (uintptr_t) NGX_ERROR) {

        if (cf->args->nelts == 2
            && (ngx_strncmp(p, "http://", sizeof("http://") - 1) == 0
                || ngx_strncmp(p, "https://", sizeof("https://") - 1) == 0
                || ngx_strncmp(p, "$scheme", sizeof("$scheme") - 1) == 0))
        {
            ret->status = NGX_HTTP_MOVED_TEMPORARILY;
            v = &value[1];

        } else {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "invalid return code \"%V\"", &value[1]);
            return NGX_CONF_ERROR;
        }

First it tries to convert the first parameter to an integer. If that fails it checks if that is an URL. If not, it bails out with the error.

Is it possible to use variable with redirect code in Nginx configuration?

1 Answers1