Install PHP-FPM 7.1 + OCI8 + Oracle


yum remove php-common
yum install php71w-fpm

Install some prerequisite

yum install php71w-pear
yum install php71w-devel
yum install php71w-pdo
yum install php71w-mbstring


Install oracle instance RPM packages
rpm -Uvh oracle-instantclient11.2-basic-11.2.0.4.0-1.x86_64.rpm
rpm -Uvh oracle-instantclient11.2-devel-11.2.0.4.0-1.x86_64.rpm

Download the OCI8 extension
tar -xvzf oci8-2.1.8.tgz
cd oci8-2.1.8/
./configure --with-oci8=shared,instantclient,/usr/lib/oracle/11.2/client64/lib/
make
make install

Edit php.ini file:
vi /etc/php.ini
extension=oci8.so

Config user php-fpm & nginx is "nginx"
chown -R userapp:nginx /path/to/web/
chmod -R 777 /var/log/nginx
chmod -R 777 /var/log/php-fpm

Start: 
service nginx start
service php-fpm start