Not sure what I'm doing wrong, but I'm trying to get gunicorn/django through nginx using only https. Here is my nginx configuration:

upstream app_server {
    server unix:/srv/django/app/run/gunicorn.sock fail_timeout=0;
}

server {
    listen 80;
    return 301 https://$host$request_uri;
}

server {
    listen 443;
    server_name app.mydomain.com;

    ssl on;
    ssl_certificate /etc/nginx/ssl/nginx.crt;
    ssl_certificate_key /etc/nginx/ssl/nginx.key;

    client_max_body_size 4G;
    access_log /srv/django/app/logs/nginx-access.log;
    error_log /srv/django/app/logs/nginx-error.log;

    location /static/ {
        alias /srv/django/app/data/static/;
    }
    location /media/ {
        alias /wrv/django/app/data/media/;
    }

    location / {
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto https;
        proxy_set_header Host $http_host;
        proxy_pass http://app_server;
    }
}

I get a 400 error on app.mydomain.com, but the app is published on mydomain.com. Is there an error in my configuration?