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——————————————————————————————————————
*** Initial setup before Ambari setup ***
——————————————————————————————————————


OS checks:



yum install wget

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ambari-server stop
ambari-agent stop
pkill -9 java
#################################
# Remove Packages
################################

yum  -y remove ambari-\*
yum -y remove hcatalog\* 
yum -y remove hive\*

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How to Set up an Ethereum Dev Environment

So you want to be an Ethereum developer! Congrats, much treasure awaits you. Developing Ethereum dapps benefits from having a well-crafted development environment. This can often be daunting to beginners, so I'm giving you my favorite dev environment to help get you started.

Once your code fortress is constructed, you'll be able to

• Compile smart contracts written in Solidity

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Docker on WSL (Windows 10 Home / Docker Toolbox) (Virtualbox instead Hyper-V)

Docker on WSL communicates with Docker on Windows from Docker Toolbox.

Install VirtualBox and Docker Toolbox on Windows.

Docker on Windows uses VM for Linux based docker containers.

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pragma solidity ^0.4.16;

interface ERC20 {
    
 function totalSupply() public constant returns (uint);
 function balanceOf(address tokenOwner) public constant returns (uint balance);
 function allowance(address tokenOwner, address spender) public constant returns (uint remaining);
 function transfer(address to, uint tokens) public returns (bool success);
 function approve(address spender, uint tokens) public returns (bool success);
 function transferFrom(address from, address to, uint tokens) public returns (bool success);

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#!/bin/bash
#title           :wildfly-install.sh
#description     :The script to install Wildfly 10.x
#more            :http://sukharevd.net/wildfly-8-installation.html
#author	         :Dmitriy Sukharev
#date            :2016-06-18T02:45-0700
#usage           :/bin/bash wildfly-install.sh
#tested-version1 :10.0.0.CR3
#tested-distros1 :Ubuntu 15.10; Debian 7,8; CentOS 7; Fedora 22 
#tested-version2 :10.0.0.Final

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# Path to boto config file, needed by gsutils
BOTO_CONFIG="/etc/boto.cfg" 

# Path in which to create the backup (will get cleaned later)
BACKUP_PATH="/mnt/data/dump/"

# DB name
DB_NAME="mydatabase"

# Google Cloud Storage Bucket Name

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Here's all you have to do to add clustering to your node.js application.

• save this code as cluster.js, and run cluster.js instead of server.js (or /bin/www, or whatever it's called for your project)
• the only line you'll need to change is the last line - it needs to point to the location of your server.js file

var cluster = require('cluster');

if (cluster.isMaster) {
  // Count the machine's CPUs
 var cpuCount = require('os').cpus().length;

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Moved to git repository: https://github.com/denji/nginx-tuning

NGINX Tuning For Best Performance

For this configuration you can use web server you like, i decided, because i work mostly with it to use nginx.

Generally, properly configured nginx can handle up to 400K to 500K requests per second (clustered), most what i saw is 50K to 80K (non-clustered) requests per second and 30% CPU load, course, this was 2 x Intel Xeon with HyperThreading enabled, but it can work without problem on slower machines.

You must understand that this config is used in testing environment and not in production so you will need to find a way to implement most of those features best possible for your servers.

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proxy_cache_path /tmp/cacheapi levels=1:2 keys_zone=microcacheapi:100m max_size=1g inactive=1d use_temp_path=off;
server {
    listen 443 ssl http2 default_server;
    listen [::]:443 ssl http2 default_server;
    server_name example.com;

    location /api/ {
        # Rate Limiting
        limit_req zone=reqlimit burst=20; # Max burst of request