Force www. and https in nginx.conf (SSL)

The following solution seems to be clear and simple, everything defined in one server block. So with this setup I force everything to https://www.domain.tld, so both handlers are here non-HTTPS and non-WWW on HTTPS. There are two IF's but if you don't want to duplicate entire SSL block two times to handle it... this is the way to do it.

server {
    listen 80;
    listen 443 ssl;

    server_name domain.tld www.domain.tld;

    # global HTTP handler
    if ($scheme = http) {
        return 301 https://www.domain.tld$request_uri;
    }

    # global non-WWW HTTPS handler
    if ($http_host = domain.tld){
        return 303 https://www.domain.tld$request_uri;
    }
}

And even better solution to avoid IF's:

# Redirect all traffic from HTTP to HTTPS
server {
    listen 80;

    server_name example.com www.example.com;

    # Destination redirect base URI
    set $RURI https://www.example.com;

    location / {return 301 $RURI$request_uri;}
}

# Redirect non-WWW HTTPS traffic to WWW HTTPS
server {
    listen 443 ssl;
    # NOTE: SSL configuration is defined elsewhere
    server_name example.com;
    return 301 $scheme://www.$host$request_uri;
}

# MAIN SERVER BLOCK
server {
    listen 443 ssl;
    # NOTE: SSL configuration is defined elsewhere
    server_name www.example.com;
}

The best way to implement WWW and HTTPS redirection is to create a new server section in Nginx config:

server {
    listen      80;   #listen for all the HTTP requests
    server_name example.com www.example.com;
    return      301         https://www.example.com$request_uri;
}

You will also have to perform https://example.com to https://www.example.com redirection. This may be done with code similar to the following:

server {
    listen              443 ssl;
    server_name         example.com;

    ssl_certificate     ssl.crt; #you have to put here...
    ssl_certificate_key ssl.key; #   ...paths to your certificate files
    return      301     https://www.example.com$request_uri;
}

And of course, you must reload Nginx config after each change. Here are some useful commands:

check for errors in the configuration:

sudo service nginx configtest

reload configuration (this would be enough to make changes "work"):

sudo service nginx reload

restart the whole webserver:

sudo service nginx restart

Important note:

All your server sections must be inside http section (or in a file included in http section):

http {
    # some directives ...
    server {
        # ...
    }
    server {
        # ...
    }
    # ...
}