nginx using OR set at regex for the map

Question

I'm trying to write a map for my website and it's working great:

map $request_uri $redirect_uri {
  /en/oldname    /en/newname;
  /de/oldname    /de/newname;
  /fr/oldname    /fr/newname;
}

until I try to implement some regex, something like this:

map $request_uri $redirect_uri {
  /(?<lang>(en|de|fr))/oldname    /$lang/newname;
}

The map above is not working, and due to the lack of debugging knowledge - I'm unable to know why. Even the basic regex (without using named captures) is not working for me:

map $request_uri $redirect_uri {
  /(en|de|fr)/oldname    /en/newname;
}

nginx 1.10.3

Please help me to figure out what am I doing wrong?

Answer 1

Mike, you should use “~” symbol to indicate a regular expression.

Look at here Module ngx_http_map_module

A regular expression should either start from the “~” symbol for a case-sensitive matching, or from the “~*” symbols (1.0.4) for case-insensitive matching. A regular expression can contain named and positional captures that can later be used in other directives along with the resulting variable.

The right configuration should be:

map $request_uri $redirect_uri {
  ~/(?<lang>(en|de|fr))/oldname    /$lang/newname;
}

Good luck!

---

2017.07.13 edited

Here is the full configuration based on the default configuration(echo directive is provided by nginx-echo-module)

#user  nobody;
worker_processes  1;

#error_log  logs/error.log;
#error_log  logs/error.log  notice;
#error_log  logs/error.log  info;

#pid        logs/nginx.pid;


events {
    worker_connections  1024;
}


http {
    include       mime.types;
    default_type  application/octet-stream;

    #log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
    #                  '$status $body_bytes_sent "$http_referer" '
    #                  '"$http_user_agent" "$http_x_forwarded_for"';

    #access_log  logs/access.log  main;

    sendfile        on;
    #tcp_nopush     on;

    #keepalive_timeout  0;
    keepalive_timeout  65;

    #gzip  on;
    map $request_uri $redirect_uri {
      ~/(?<lang>(en|de|fr))/oldname    /$lang/newname;
    }

    server {
        listen       80;
        server_name  localhost;

        #charset koi8-r;

        #access_log  logs/host.access.log  main;

        location / {
            echo $redirect_uri;
        }

        #error_page  404              /404.html;

        # redirect server error pages to the static page /50x.html
        #
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }

        # proxy the PHP scripts to Apache listening on 127.0.0.1:80
        #
        #location ~ \.php$ {
        #    proxy_pass   http://127.0.0.1;
        #}

        # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
        #
        #location ~ \.php$ {
        #    root           html;
        #    fastcgi_pass   127.0.0.1:9000;
        #    fastcgi_index  index.php;
        #    fastcgi_param  SCRIPT_FILENAME  /scripts$fastcgi_script_name;
        #    include        fastcgi_params;
        #}

        # deny access to .htaccess files, if Apache's document root
        # concurs with nginx's one
        #
        #location ~ /\.ht {
        #    deny  all;
        #}
    }


    # another virtual host using mix of IP-, name-, and port-based configuration
    #
    #server {
    #    listen       8000;
    #    listen       somename:8080;
    #    server_name  somename  alias  another.alias;

    #    location / {
    #        root   html;
    #        index  index.html index.htm;
    #    }
    #}


    # HTTPS server
    #
    #server {
    #    listen       443 ssl;
    #    server_name  localhost;

    #    ssl_certificate      cert.pem;
    #    ssl_certificate_key  cert.key;

    #    ssl_session_cache    shared:SSL:1m;
    #    ssl_session_timeout  5m;

    #    ssl_ciphers  HIGH:!aNULL:!MD5;
    #    ssl_prefer_server_ciphers  on;

    #    location / {
    #        root   html;
    #        index  index.html index.htm;
    #    }
    #}

}

And this is my test case:

yxr nginx # curl localhost/en/oldname
/en/newname
yxr nginx # curl localhost/de/oldname
/de/newname
yxr nginx # curl localhost/fr/oldname
/fr/newname
yxr nginx # curl localhost/cn/oldname

yxr nginx #

---

2017.07.14 edited

As @Mike pointed out, this requires at least nginx/1.11.0.