Remove www subdomain in nginx and puma config - ruby-on-rails

Question

I'm using puma and nginx to run a rails 3.2 app on AWS. I terminate my HTTPS on the loadbalancer (ELB). How can I redirect www.mydomain.com to mydomain.com? My config below does not work.
user nginx;
worker_processes auto;
worker_rlimit_nofile 100000;
error_log /var/log/nginx/error.log;
pid /var/run/nginx.pid;
events {
use epoll;
worker_connections 1024;
multi_accept on;
}
http {
include /etc/nginx/mime.types;
default_type application/octet-stream;
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';
access_log /var/log/nginx/access.log main;
sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 65;
keepalive_requests 200;
reset_timedout_connection on;
types_hash_max_size 2048;
# Load modular configuration files from the /etc/nginx/conf.d directory.
# See http://nginx.org/en/docs/ngx_core_module.html#include
# for more information.
include /etc/nginx/conf.d/*.conf;
index index.html index.htm;
upstream myapp {
# Path to Puma SOCK file
server unix:/var/www/nginx-default/myapp/tmp/sockets/puma.sock fail_timeout=0;
}
server {
listen 80;
server_name www.my-app.com;
return 301 $scheme://my-app.com$request_uri;
}
server {
listen 80;
server_name my-app.com;
root /var/www/nginx-default/myapp/public;
#charset koi8-r;
# set client body size (upload size)
client_max_body_size 100M;
location / {
proxy_pass http://myapp; # match the name of upstream directive which is defined above
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
# We don't need .ht files with nginx.
location ~ /\.ht {
deny all;
}
open_file_cache max=1000 inactive=20s;
open_file_cache_valid 30s;
open_file_cache_min_uses 2;
open_file_cache_errors on;
}
}
If I remove
server {
listen 80;
server_name www.my-app.com;
return 301 $scheme://my-app.com$request_uri;
}
and use
server {
listen 80;
server_name localhost;
root /var/www/nginx-default/myapp/public;
#...
}
it works but does not handle the www subdomain.

Answer 1

This is a speculative answer, as I do not use AWS and ELB. However, using $scheme in your redirect will result in HTTPS being redirected to HTTP:
If you do not accept HTTP at the ELB, you should redirect to HTTPS only, with:
server {
listen 80;
server_name www.my-app.com;
return 301 https://my-app.com$request_uri;
}
However, if you accept either HTTP or HTTPS at the ELB, you should be able to use the X-Forwarded-Proto header inserted by the ELB. Try this:
server {
listen 80;
server_name www.my-app.com;
return 301 $http_x_forwarded_proto://my-app.com$request_uri;
}