Nginx rewrite non-www url to www

One of my project facing issue with non-www url. At Browser side we are calling multiple services from different domain and same time we are sharing same cookies for calling services from our website. But it was giving authentication failure for our services.

Issue:

We have embedded zimbra collaboration suite into our rails application. Once user logged into our application, he will automatically gets Single signed into zimbra collaboration suite. We ware showing zimbra UI in separate iframe on web page.

Zimbra has nice feature to extend their own functionality using zimlet.

Zimlet is simply JavaScript code which runs on client side(On Browser).

Using the power of zimlet we want to access the services of our own application, where we ware sharing cookies which already got created for portal on browser side when user signed in.

Every thing was working fine on production. But some time some users were facing issue of authentication failure for zimlet functionality, even though they have signed in into rails application.

After digging into issue, found that some users accessing the application using without www. i.e "https://abcrails.com", and zimlet was trying to access a rails application using "https://www.abcrails.com" where authentication is failing. As cookies ware created for "https://abcrails.com" and not for "https://www.abcrails.com"

For this I have only one solution depending on my requirements, is force non-www url to www.

So following nginx configuration is for:

1. Force http reuest to https

2. Force non-www url to www