How do I deploy react app under subdirectory

I have nginx proxypass configured mapping https://newcompany.com/subdir to http://someserver/login

I have access to vm corresponding to someserver. Am copying contents of build directory of my react app to apache2 at var/www/html directory of someserver.

Client information

I have specified following in react:

<Router  basename="subdir">

following in package.json:

"homepage": "/subdir",

and following in my .env.staging:

 PUBLIC_URL=https://newcompany.com/subdir

Server configuraiton

I am running spring boot server running at someserver's port 8080. It has following configurations:

• .logout(l -> l.logoutSuccessUrl("http://newcompany/subdir/login").permitAll()) ref
• .oauth2Login().defaultSuccessUrl("http://newcompany/subdir/dashboard") ref , ref

Behavior

When I hit https://newcompany.com/subdir/login I get correct page. It has "Login with Google" button. But after successful login it redirects to https://newcompany.com/subdir/login page instead of https://newcompany.com/subdir/dashboard. If I hit https://newcompany.com/subdir/dashboard, it redirects to https://newcompany.com/subdir/login. Now if I try to hit http://someserver/subdir/dashboard, it shows me logged in user and I can access the whole website. But why it is not getting redirected to https://newcompany.com/subdir/dashboard after successful login? what could be the reasons?

PS:

I checked the network traffic also.

1. After successful login google oauth redirects to http://someserver:8080/login/oauth2/code/google with authorization code= in is url params
2. Then http://someserver:8080/login/oauth2/code/google redirects to http://newcompany.com/subdir/dashboard with cookie JSESSIONID
3. Then http://newcompany.com/subdir/dashboard redirects to itself twice with same JSESSIONID

Note that after google login, I could not see http://someserver:8080/login/oauth2/code/google and http://newcompany.com/subdir/dashboard in the browser address bar. So after oauth login I get to see directly https://newcompany.com/subdir/login in the browser address bar. Also notice that https://newcompany.com/subdir/login never appears in the network traffic.