i have two type of web pages,

1. static html which has static content
2. react js where i have my app functionalities

below is my nginx conf file

# https server
server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;

    server_name dev.app.in;

    ssl_certificate /etc/letsencrypt/live/dev.app.in/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/dev.app.in/privkey.pem;

    location  = / {
    resolver 1.1.1.1 ipv6=off valid=30s; 
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
    proxy_pass http://app-landing-pre_prod:80;

    }
    location /fmApp/ {
    resolver 1.1.1.1 ipv6=off valid=30s;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
        proxy_pass http://app-ui-pre_prod:80/fmApp;
    }

    location /admin/ {
        resolver 1.1.1.1 ipv6=off valid=30s;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
        proxy_pass http://app-ui-pre_prod:80/admin;
    }

    location /api {
        resolver 1.1.1.1 ipv6=off valid=30s;
        proxy_pass http://app-pre_prod:8080;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
   }
}

in above conf , localtion with = / will proxy to my static html page, from there i have redirect functionality which redirect to same domain with different uri

my redirect url https://dev.app.in/app/customer/{id}

here my static page is loading properly but react js was not loading and getting empty web page.

when i replace localtion = / proxy to my react app , i am able to launch my react js app.

seems like location url matching is causing the issue, i have configured as per the below regex pattern discussed.

Guide on how to use regex in Nginx location block section?