nginx load balancing nodejs

check_rpm.sh

#!/bin/bash

start_new_node() {
  BASE=8080
  INCREMENT=1
  port=$BASE
  isfree=$(netstat -tapln | grep $port)

  while [[ -n "$isfree"]]; do
   port = $[port+INCREMENT]
   isfree=$(netstat -tapln | grep $port)
  done
  PORT=$isfree forever start /var/www/hello-world-node/main.js
  echo "server 127.0.0.1:$isfree max_fails=0 fail_timeout=10s weight=1" >> /etc/nginx/upstream.conf
  sed -i -e '/##START_SERVERS/,/##END_SERVERS/{//!d;/##START_SERVERS/r /etc/nginx/upstream.conf' -e '}' /etc/nginx/nginx.conf
 service nginx reload
}

stop_new_node() {
  lastserver=sed -n '$p' /etc/nginx/upstream.conf
  #lastserver=grep -B1 '##END_SERVERS' /etc/nginx/upstream.conf | grep -v '##END_SERVERS'
  lastport=${lastserver##*:} | head -n1 | awk '{print $1;}' 
  
  #Condition to be handled: Ensure that all servers aren't killed.
  if [ "$lastport" -ne 8080]
  then
    PORT=$lastport forever stop /var/www/hello-world-node/main.js
  fi
  sed "/$PORT/d" /etc/nginx/upstream.conf
  sed "/$PORT/d" /etc/nginx/conf.d/nodejs.conf
  service nginx reload
}

output1=`wget -O -q -t 3 -T 3 http://test.com/basic_status`
sleep 60
output2=`wget -O -q -t 3 T 3 http://test.com/basic_status`

tmp1_reqpmin=`echo ${out1}|awk '{print $10}'`
tmp2_reqpmin=`echo ${out2}|awk '{print $10}'`
reqpmin=`expr $tmp2_reqmin - $tmp1_reqmin`
if [ "$reqpmin" gt 100]
then
   start_new_node();
fi

if [ "$reqpmin" lt 100]
then
   stop_new_node();
fi

Instructions.md

Download Repo in /var/www/ folder.

nginx_install.sh

#!/bin/bash
sudo apt-get update
sudo apt-get install -y openssh-server libssl-dev git g++ make python-software-properties
sudo apt-get install nginx nginx-extras

nodejs.conf

upstream node_cluster {  
    #START_SERVERS
    server 127.0.0.1:8080 max_fails=0 fail_timeout=10s weight=1;
    #END_SERVERS
    ip_hash;
    keep_alive 512;
}

server {  
    listen 80;
    server_name test.com www.test.com;

    location / {
        proxy_next_upstream error timeout http_500 http_502 http_503 http_504;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_set_header X-NginX-Proxy true;

        proxy_pass http://node_cluster/;
        proxy_redirect off;
    }
    location /basic_status {
        stub_status on;
    }
    
}

nodejs_install.sh

#!/bin/bash
# This script installs node in ' $HOME/local/node ' directory without sudo

# Store script's filename in $SELF_NAME
SELF_NAME=$(basename $0)

# Prints warning/error $MESSAGE in red foreground color (for [E]rror messages)
red_echo() {
    echo -e "\e[1;31m[E] $SELF_NAME: $MESSAGE\e[0m"
}

# Prints success $MESSAGE in green foreground color (for [S]uccess messages)
green_echo() {
    echo -e "\e[1;32m[S] $SELF_NAME: $MESSAGE\e[0m"
}

# Prints $MESSAGE in blue foreground color (for [I]nfo messages)
blue_echo() {
    echo -e "\e[1;34m[I] $SELF_NAME: $MESSAGE\e[0m"
}

# Function to ensure success of previous command.
# This causes the script to exit if previous command exited with non-zero status
function ensure_success {
    return_status="$1"
    error_message="$2"
    success_message="$3"
    if [ "$return_status" -ne 0  ];then
        MESSAGE=$error_message ; red_echo
        exit
    else
        MESSAGE=$success_message ; green_echo
    fi
}

# Creating local directories
MESSAGE="Creating directory $HOME/local/node\n"; blue_echo
mkdir -p $HOME/local/node
MESSAGE="Directory created\n";blue_echo

# creating an cd-ing to Downolads directory
MESSAGE="Creating a Node directory and entering  in to it \n"; blue_echo
mkdir -p $HOME/Node/
cd $HOME/Node
MESSAGE="Now in Node directory\n";blue_echo

#Downloading the linux tar.gz node package from http://nodejs.org/download/
MESSAGE="Downloading the node package for linux\n"; blue_echo
wget https://nodejs.org/dist/v5.0.0/node-v5.0.0-linux-x64.tar.gz
ensure_success "$?" "Downloading error " " Successfully downloaded "

NODE_PACKAGE=`ls *.tar.gz`

# Extracting the node package
MESSAGE="Extracting the node package \n";blue_echo
tar xzf $NODE_PACKAGE -C $HOME/local/node --strip-components=1

MESSAGE="nodejs Enviroment Setup\n"; blue_echo
echo '#nodejs Enviroment Setup' >> $HOME/.bashrc

MESSAGE="exporting PATH ==> PATH=$HOME/local/node/bin:$PATH\n";blue_echo
echo 'export PATH=$HOME/local/node/bin:$PATH' >> $HOME/.bashrc

MESSAGE="exporting NODE_PATH ==> NODE_PATH=$HOME/local/node/lib/node_modules\n";blue_echo
echo 'export NODE_PATH=$HOME/local/node/lib/node_modules' >> $HOME/.bashrc

MESSAGE="Removing Node directory packages\n"; blue_echo
rm -rf $HOME/Node
ensure_success "$?" "Error removing Downloads directory" "Removed Downloads directory"

MESSAGE="Loading node and npm \n";green_echo
echo 'source $HOME/.bashrc'

MESSAGE="After sourcing bashrc : You can verify the versions as below  \n"; blue_echo
echo 'node -v '
echo 'npm -v '

echo 'npm install -g forever'

reqpmin.conf

description "Make sure reqmin is running"

start on local-filesystem
stop on shutdown

respawn 
exec /etc/check_rpm start

Run.sh

#!/bin/bash
sudo nginx_install.sh
sudo nodejs_install.sh
sudo touch /etc/nginx/upstream.conf
mkdir -p /var/www/
cd /var/www/
git clone git@github.com:chetandhembre/hello-world-node.git
cd /var/www/hello-world-node/
forever start main.js
PORT=8081 forever start main.js
chmod +x check_rpm.sh
cp check_rpm.sh /etc/check_rpm
sudo service reqpmin start