---
title: 'Centrality Test Harness'
---

Perses
===

## Table of Contents

[TOC]

## Overview

To exercise Centrality's blockchain behaviors under certain loads or networking conditions, we introduce Perses to effortlessly reproduce a blockchain deployment and simulate/emulate various conditions when a chain running on your localhost.

>Why it named `Perses` ?
The name came from Greek Titan `God of Destruction` - exactly what it means to be: breaking our blockchain in different ways

## Getting started

1. Clone the [Centrality test harness repo](https://bitbucket.org/centralitydev/blockchain-test-harness/src/master/)
3. In the project root, run the file `install.sh` to setup `perses`
4. Open terminal in the same project root path, execute `perses -h` you should see the following output

Usage: perses [options] [command]

Test harness for Centrality blockchain

Options:
  -v, --version   output the version number
  -h, --help      display help for command

Commands:
  send [options]  send multiple Generic-Asset transactions to blockchain
  blockchain      Manage blockchain network on local
  netem           Manage containers' networking emulations using linux tc core
  monitor         Metrics collections and monitoring setup for localhost
  help [command]  display help for command

## Setup a local blockchain network with Perses
> The default genesis block holding following accounts as endowed and validators: Alice, Bob, Charlie, Dave, Eve, Melissa, James, Dustin, Bonnie, Christine. For Perses's blockchain commands to work, if you specified your own genesis block please make sure keep these accounts' data

$ perses blockchain init -h                                          
Usage: perses blockchain init [options]

Initialise blockchain network on local

Options:
  --image <image>                  The centrality blockchain image to run (default: "cennznet/cennznet:1.0.1")
  --genesis <genesis>              The genesis block file name for this blockchain (default: "cennznet_dev")
  --validators <validators>        Number of initialised validators for this blockchain (default: "5")
  --log <log>                      Log level permodule (default: "info")
  -h, --help                       display help for command

Run

perses blockchain init --validators 10 

Will be the same as

perses blockchain 
        --image cennznet/cennznet:1.0.1 \
        --genesis cennznet_dev \
        --validators 10 \
        --log info

Which initialized a `cennznet` blockchain with 10 validators, using the genesis json file name `cennznet_dev` located at `/chain-spec` folder.

### Partitioning network mode

perses net-config -p

Default `networking` will connect all validators to a default `blockchain` virtual network.

If the `-p` flag was set to `partition`, the blockchain will thereafter need at least `--validator` set to `10` and then it will create 2 separate virtual networks called `blockchain-1` and `blockchain-2`.

After that it would connect 5 validators to each networking group forming 2 partitioned network clusters doesn't know about eachother.

### Teardown local blockchain

Run

perses blockchain teardown --image cennznet/cennznet:1.0.1

Will do the following tasks:
* Stop and remove all running containers matches the image ancestor
* Delete the local data storage `node_data` folder
* Remove all `blockchain` virtual network

## Monitoring
Perses has built in a Grafana dashboard config and Prometheus server to collect and populate the chain's status as well as its functions when running transactions on chain.

### Setup monitor servers
#### Configure Prometheus setup

In the prometheus yaml

/prometheus/prometheus.yml

>This change is required to populate the metrics from app's server to Prometheus server

Change the target's ip with your computer/host ip

- targets: ['192.168.10.112:8080']

#### Run the servers containers

perses monitor init

You should see following containers up and running on port `9090` and `3000` for `prometheus` and `grafana` servers respectively.

Both containers (prometheus and grafana) running on a virtual network with addresses `10.10.1.3` and `10.10.1.2` respectively


1. Login Grafana dashboard
Url: http://localhost:3000
Grafana default credential:
>admin/admin
2. Configure datasource

http://localhost:3000/datasources

Save & test
3. Import dashboard


Upload the `dashboard.json` file in `<project root path>/grafana`

Test harness dashboard should show up


4. Run command `perses send` and watch the monitor dashboard


## Network emulation

Use perses's `netem` subcommand

## Examples
TBC