Laravel on Nginx: accessing to "public/" of the app results in "Permission denied" even though it has the same user as Nginx – CentOS

I’ve been trying to deploy a brand new Laravel 6 app on Nginx with CentOS 7, but I’m getting the following error messages on the error log.

*13 stat() "/ROOT_OF_APP/public/" failed (13: Permission denied), 
client: 127.0.0.1, server: HOST_NAME, request: "GET / HTTP/1.1", host: "HOST_NAME"

*13 stat() "/ROOT_OF_APP/public/" failed (13: Permission denied), 
client: 127.0.0.1, server: HOST_NAME, request: "GET / HTTP/1.1", host: "HOST_NAME"

*13 FastCGI sent in stderr: "Primary script unknown" while reading response header from upstream, 
client: 127.0.0.1, server: HOST_NAME, request: "GET / HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "HOST_NAME"

The first line says "/ROOT_OF_APP/public/" failed (13: Permission denied).

So, I ran sudo chown -R nignx:nginx /ROOT_OF_APP/public/ and sudo chmod -R 775 /ROOT_OF_APP/, and made sure that the user and group of both Nginx and PHP-FPM are nginx (this will be explained below).

The question is:
why can’t nginx access “public” even though the owner/user is nginx ?

(The 3rd message (Primary script unknown) also bothers me, but I don’t know if this is to do with the permission issue)

In /etc/php-fpm.d/www.conf, you see these lines.

user = nginx
group = nginx

listen.owner = nginx
listen.group = nginx
listen.mode = 0660

In /etc/nginx/nginx.conf, you see the line.

user nginx;

(I’d like to note that the OS is CentOS 7, so it doesn’t have www-data user/group, unlike Ubuntu.)

If I run ps aux | grep php-fpm…

user     24394  0.0  0.0 112708   988 pts/1    S+   14:28   0:00 grep --color=auto php-fpm
root     26979  0.0  0.0 306464 10520 ?        Ss   13:57   0:00 php-fpm: master process (/etc/php-fpm.conf)
nginx    26985  0.0  0.0 318712  5804 ?        S    13:57   0:00 php-fpm: pool www
nginx    26986  0.0  0.0 318712  5796 ?        S    13:57   0:00 php-fpm: pool www
nginx    26987  0.0  0.0 318712  5800 ?        S    13:57   0:00 php-fpm: pool www
nginx    26988  0.0  0.0 318712  5800 ?        S    13:57   0:00 php-fpm: pool www
nginx    26989  0.0  0.0 318712  5804 ?        S    13:57   0:00 php-fpm: pool www

If I ran ps aux | grep nginx…

root      2990  0.0  0.0 122420  5608 ?        Ss   14:01   0:00 nginx: master process /usr/sbin/nginx
nginx    26985  0.0  0.0 318712  5804 ?        S    13:57   0:00 php-fpm: pool www
...
# The 2nd line is repeated several times
...
nginx    31299  0.0  0.0 134672  4212 ?        S    14:15   0:00 nginx: worker process
# This "nginx: worker process" is repeated several times too

I’m completely clueless… any advice will be appreciated.

PS

Here’s how the config file looks like.

server {
        listen 80;
        listen [::]:80 ipv6only=on;

        access_log /var/log/nginx/MY-APP-access.log;
        error_log /var/log/nginx/MY-APP-error.log;

        root /ROOT_OF_APP/public;
        index index.php index.html index.htm;

        server_name HOST_NAME;

          location / {
            try_files $uri $uri/ /index.php?$args;
          }

          location ~* .php$ {
              include /etc/nginx/fastcgi_params;
              fastcgi_pass 127.0.0.1:9000;
              fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
              fastcgi_index index.php;
        }

        location = /favicon.ico { log_not_found off; access_log off; }
          location = /robots.txt  { log_not_found off; access_log off; }
}

sudo nginx -t shows that the syntax is ok.

Also, the "SELinux enforcing" status has been changed into “Permissive”, so SELinux shouldn’t be the cause of this issue.