How to redirect root domain to www using Openshift v2 and nginx?

I am not able redirect my example.com request to www.example.com and they are now both different websites, pointing to the same application.

Background:

I have installed php 7 with nginx on Openshift ver. 2 using this. I have added 2 aliases for the application deployed, as follows:

1. Application URL: myapp.rhcloud.com;
   
   Domain Name: www.example.com


2. Application URL: myapp.rhcloud.com;
   Domain Name: example.com

I have also added the following DNS detailes in CNAME:

1. Name: www.example.com; Value: myapp.rhcloud.com


2. Name: @; Value: www.example.com

My nginx config file (erb) is as follows:

server {
    root              <%= ENV['OPENSHIFT_REPO_DIR'] %>/www;
    listen            <%= ENV['OPENSHIFT_PHP_IP'] %>:<%= ENV['OPENSHIFT_PHP_PORT'] %>;
    server_name       <%= ENV['OPENSHIFT_APP_DNS'] %>;
    index             index.php index.html index.htm <%= ENV['NGINX_EXTRA_INDEX'] %>;
    set_real_ip_from  <%= ENV['OPENSHIFT_PHP_IP'] %>;

    real_ip_header    X-Forwarded-For;

which becomes:

server {
    root              /path/to/my/app-root/folder/;
    listen            127.11.2.1:8080;
    server_name       myapp.rhcloud.com;
    index             index.php index.html index.htm ;

    set_real_ip_from  127.11.2.1;
    real_ip_header    X-Forwarded-For;

I have tried to add another server block in my nginx config file like the following:

server {
    server_name example.com;
    return 301 https://www.example.com$request_uri;
}

However I am not sure what should I use in place of example.com.