server-setup.md

sudo apt-get update

supervisord

sudo apt install nginx -y
sudo service supervisor start
sudo service supervisor status

sudo supervisorctl   # Launch interactive supervisord controller

Edit:

/etc/supervisor/supervisord.conf

[include]
files = /var/www/ineedempathy/supervisord.conf

Nginx

sudo apt install supervisor

/etc/nginx/sites-available/ineedempathy

upstream empathyserver {
    hash $request_uri;
    server 127.0.0.1:8000;
    server 127.0.0.1:8001;
    server 127.0.0.1:8002;
    server 127.0.0.1:8003;
    server 127.0.0.1:8004;
}
server {
        listen 80;
        listen [::]:80;
        server_name ineedempathy.com;

        location / {
                include proxy_params;
                proxy_pass http://empathyserver;
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection "Upgrade";
        }

        location ~ \.(ico|png|json|txt) {
                index /var/www/ineedempathy/templates;
                root /var/www/ineedempathy/templates;
        }
}

ln -s /etc/nginx/sites-available/ineedempathy /etc/nginx/sites-enabled/ineedempathy

Horizontal Scaling

Run nginx on the leader droplet. Proxy the incoming requests to multiple follower droplets using the hashing.

upstream empathyserver {
    hash $request_uri;
    server droplet1:8000;
    server droplet1:8001;
    server droplet2:8000;
    server droplet2:8001;
    server droplet3:8000;
    server droplet3:8001;
}

In the future we might look into the digitalocean load balancer instead of using nginx.

Scaling Nginx

Single Core Limits

We usually can handle around ~500 connections. That's around ~100 rooms/~5 people per room.

4 Core Limits

If we go into Digital Ocean we can scale the application up, but it will shut down the server, losing all current connections. If we scale this up to 4 core (vs 1 we are at now) and change this nginx config, we can handle around ~2.6k connections on the single droplet.

Scaling Configuration

systemctl edit --full nginx.service

• Change 1048576 to ulimit -Hn

[Service]
LimitNOFILE=1048576

/etc/nginx/nginx.conf

• Change 1024 to ulimit -n * CORE_COUNT
• Change 1048576 to ulimit -Hn

worker_rlimit_nofile 1048576;

events {
    worker_connections 1024;
}

Python

Install from source

sudo apt install wget build-essential checkinstall -y
sudo apt install libncursesw5-dev libssl-dev libsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev libffi-dev zlib1g-dev -y
cd /opt
sudo wget https://www.python.org/ftp/python/3.9.6/Python-3.9.6.tgz
tar xzf Python-3.9.6.tgz
cd Python-3.9.6
sudo ./configure --enable-optimizations 
sudo make altinstall
python3.9 -V
sudo ln -s /usr/local/bin/pip3.9 /usr/bin/pip
sudo ln -s /usr/local/bin/python3.9 /usr/bin/python
python -V

Server Users

Enable no sudo for our users

# add users
sudo adduser amjith
sudo adduser baylee
sudo adduser web-runner

ln -s /var/www/ineedempathy ~/ineedempathy
runuser -l amjith -c 'ln -s /var/www/ineedempathy ~/ineedempathy'
runuser -l baylee -c 'ln -s /var/www/ineedempathy ~/ineedempathy'
runuser -l web-runner -c 'ln -s /var/www/ineedempathy ~/ineedempathy'

# add group
groupadd -g 10000 webteam
usermod -a -G webteam root
usermod -a -G webteam amjith
usermod -a -G webteam baylee
usermod -a -G webteam web-runner

# don't require passwords on sudo
sudo update-alternatives --config editor
sudo visudo

baylee ALL=(ALL) NOPASSWD: ALL
amjith ALL=(ALL) NOPASSWD: ALL
web-runner ALL=(ALL) NOPASSWD: ALL

Permissions

As root, ensure each user has the right authorized keys.

Repeat for every user amjith, baylee and web-runner.

cd /home/web-runner
mkdir -m 700 .ssh
chown web-runner:web-runner .ssh
cp ~/.ssh/authorized_keys ./.ssh
chown web-runner:web-runner ./.ssh/authorized_keys

Project Files

cd /var/www
mkdir ineedempathy
chown root:webteam /var/www/ineedempathy
chmod 775 /var/www/ineedempathy