Using a variable in the resolver directive

Hi,
I'm trying to use the resolver directive with an environment variable because DNS resolver 127.0.0.11 didn't work. However when I am running my docker container I get the folloeing error nginx: [emerg] host not found in resolver "$resolver_ip" in /usr/src/app/nginx.conf:25. I'm adding the Docker file and the nginx.conf
Dockerfile

FROM nginx:1.14.2-alpine

RUN  mkdir -p /run/nginx && \
     apk add nginx-mod-http-lua
     
WORKDIR /usr/src/app

COPY build /usr/src/app/build
COPY mime.types /usr/src/app

COPY nginx.conf /usr/src/app

EXPOSE 8080

CMD [ "nginx", "-c", "/usr/src/app/nginx.conf", "-g", "daemon off;" ]

nginx.conf

load_module /usr/lib/nginx/modules/ndk_http_module.so;
load_module /usr/lib/nginx/modules/ngx_http_lua_module.so;

env SERVER_URL;
env RESOLVER_IP;

pcre_jit on;

events {

}

http {

    lua_load_resty_core off;

    include /usr/src/app/mime.types;
    default_type  application/octet-stream;

    sendfile on;


    server {
        set_by_lua $resolver_ip 'return os.getenv("RESOLVER_IP")';

        resolver $resolver_ip;
        
        set_by_lua $server_url 'return os.getenv("SERVER_URL")';

        listen 8080;

        location /db/ {
            rewrite ^/db(.*)$ $1 break;
            proxy_pass $server_url/clientToDBApi$uri$is_args$args;
        }

        location / {
            root /usr/src/app/build;
            index index.html;
            try_files $uri $uri/ /index.html;
        }
    }
}

please help, couldn't get into the google group

Start with the resolver and set_by_lua directives in nginx.conf, then inspect the Dockerfile and the container startup environment for how RESOLVER_IP is supplied. Reproduce the nginx startup error and determine what configuration is needed for the resolver value to be accepted; done means the container starts without the reported host-not-found error.