Check if sticky sessions are working between two Meteor apps

Hi I am using this Nginx config to load balance between two Meteor apps on two DigitalOcean servers:

Server 1: Nginx on port 80 with Meteor running on port 3000.
Server 2: Meteor running on port 3000.

upstream backend {
    ip_hash; # Is this enough for Sticky Session?
    server; # Server 1
    server; # Server 2

server {
    listen 80;

    location / {
        proxy_pass http://backend;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_set_header Host $host;
  1. Is ip_hash enough to enable Sticky Session?
  2. How can I test if Sticky Session is actually working?

Am I missing something?