Octane-Sunu

Decentralized Voting Dapp running on the ethereum (Rinkeby) testnet blockchain.

Demo

1. Install MetaMask extension for your browser.
2. Click on MetaMask icon, Select Rinkeby Test Network from upper right options dropdown.
3. Create your wallet.
4. Get some ethers from here
5. Demo

Developing

Prerequisites

node ^9.11
npm ^6.0.1
Homebrew 1.6.0

Blockchain Setup

1. Install geth:

brew tap ethereum/ethereum
brew install ethereum

2. Connect to the Ethereum testnet and sync your node:

geth --rinkeby --fast --rpc --rpcapi personal,db,web3,eth,miner,net,txpool --cache 1024 --rpcport 8545 --rpcaddr 127.0.0.1 --rpccorsdomain 'http://localhost:4200'

3. Wait while your node is being synced.

Local Development Setup

1. Install Truffle Framework:

npm install -g truffle

2. Install dependencies in package.json by running npm install.

3. Open truffle console to create a new account:

web3.personal.createAccount('passphrase')

4. Unlock your account:

web3.personal.unlockAccount('Your_wallet_addess', 'passphrase', gas_limit)

5. Check weather node is synced, type web3.eth.syncing, it should return 'false' once it's done syncing.

6. Compile the *.sol files using this command: truffle compile

We can also use solc to compile solidity files, Solc is node.js library and command-line-tool used to compile solidity files. It requires loading solidity code into string variable then call solc.compile(<stringified code>) method to compile into artifacts. If compilation is successful then we can get Application Binary Interface (ABI) and Bytecode from its contents.

7. Deploy the compiled artifacts to the rinkeby network:

truffle migrate --network rinkeby

In migration phase. Migrations are javascript files under ~/migrations directory. These files are used by truffle to stage deployment tasks onto Ethereum blockchain. Deployed code onto blockchain is immutable. This immutability is one of the big advantages of blockchains such as Ethereum i.e, If we update any change and deploy again, the old code will still be in the blockchain untouched along with all the data stored in it.

At the beginning of migration, Truffle runs 1_initial_migration scirpt from '~/migrations' directory. The filename is prefixed with a number to indicate whether the migration ran successfully. However truffle migrate command requires Migrations.sol. Which has a specific interface that get deployed onto blockchain initially and won't be changed in future. There is a function setCompleted in the following that triggers every time as a migration step is completed successfully.

pragma solidity ^0.4.22;

contract Migrations {
  address public owner;
  uint public last_completed_migration;

  constructor() public {
    owner = msg.sender;
  }

  modifier restricted() {
    if (msg.sender == owner) _;
  }

  function setCompleted(uint completed) public restricted {
    last_completed_migration = completed;
  }

  function upgrade(address new_address) public restricted {
    Migrations upgraded = Migrations(new_address);
    upgraded.setCompleted(last_completed_migration);
  }
}

For the current migration 1_initial_migration has exposed a function with parameters of which deployer object is in first place. This deployer object is the main interface to stage current deployment task onto blockchain. It is used to call its deploy method deployer.deploy(Migrations) which truffle gets to deploy the sourcefile.

The subsequent step is to executes is 2_deploy migration script file. This migration starts with requiring 'Voting.sol', This Voting.sol is developed using Remix IDE and added functionality initializing proposals and vote count for each candidate and more. However it also needs deployer object to call deploy method to stage current deployment task with additional parameters in the following syntax.

const Voting = artifacts.require("./Voting.sol");

module.exports = function(deployer) {
  deployer.deploy(Voting, <constructor parameters>, { gas: 6700000 });
}

Besides passing Voting as first parameter followed by its constructor parameters. gas limit is also passed that tells how much max gas would consumed to execute this transaction onto blockchain. However its value should be in between low and high end configured by the network. Furthermore we can use Remix IDE to estimate the transaction cost.

Now if we change any thing in our 'Voting.sol' we need to create another migration script alongside with incrementing prefix in order to intact immutablity of code deployed.

8. Start the app server: ng serve

9. Navigate to localhost:4200

Unit Tests / E2E

1. Install ganache (in memory blockchain) to execute tests locally:

ganache-cli is written in Javascript and distributed as a Node package via npm.

npm install -g ganache-cli

2. To run the ganache-cli execute ganache-cli in terminal.

3. To Unit test Solidity files, run the following:

truffle test

Output:

4. For Unit tests, run the following:

ng test --watch false

Output:

5. For E2E testing, run the following

ng e2e

Output:

Code Coverage

With the Angular CLI we can create code coverage reports. This allow us to see any parts of our code base that may not be properly tested by our unit tests. The output of code coverage reports are created with coverage inside the root directory project. To see the code-coverage run the following:

ng test --watch=false --code-coverage

Output:

Travis CI

This application has a default build environment with the steps for testing, building and deploying in the following:

script:
  - ganache-cli 1> /dev/null &
  - sleep 5
  - truffle compile
  - truffle migrate
  - truffle test
  - ng lint
  - ng test --watch false
  - npm run e2e
  - ng build --base-href --prod

Deploy the application online with IPFS

0. Build the project, run the following:

ng build --base-href --prod

ng build compiles the application into an ~/dist directory.

1. Install IPFS from https://ipfs.io/docs/install/.

2. After installing start IPFS daemon in new terminal to start a node, run the following:

ipfs daemon

3. Add dist/ directory to the network, run ipfs add -r dist/ in separate terminal:

4. To publish the content, run ipfs name publish <hash-of-dist-directory>

5. Navigate