Setup wordpress container in subdirectory with nginx and mariadb

Ok guys here is the problem: i have my webserver serving a website, a cms and mobile app api using a subdirectory approach like this

• localhost -> site
• localhost/cms
• localhost/api

everything is built using docker compose

services:
  server:
    build: ./docker/nginx
    links:
      - fpm
    ports:
      - 80:80
      - 443:443

  fpm:
    build: ./docker/php
    links:
      - database
      - smtp

  database:
    build: ./docker/mariadb
    volumes:
      - dbdata:/var/lib/mysql

volumes:
  dbdata:

What i'd like to do is to add 2 new containers: one for wordpress and one for the wordpress db in order to proxy pass every request to mydomain.dom/blog to the wordpress container. I was able to pass the request using a nginx config like below but unfortunately i'm fighting with the container which keeps redirecting everything to localhost instead of localhost/blog, i think i'm missing some config in wordpress.

location /blog/ {
    proxy_http_version 1.1;
    proxy_buffering off;
    proxy_read_timeout    90;
    proxy_connect_timeout 90;
    proxy_redirect        off;
    proxy_pass http://blog:80; # the wordpress container name

    proxy_set_header Host $host;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection $proxy_connection;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $proxy_x_forwarded_proto;
    proxy_set_header X-Forwarded-Ssl $proxy_x_forwarded_ssl;
    proxy_set_header X-Forwarded-Port $proxy_x_forwarded_port;

    # Mitigate httpoxy attack (see README for details)
   proxy_set_header Proxy "";
}

# Cms stuff
location /cms/ {
    try_files $uri $uri/ /staff/index.php?$args;

    include _php.conf; # php-fpm setup
}

# Site stuff
location / {

    try_files $uri $uri/ /index.php?$args;

    include _php.conf; # php-fpm setup
}