Cynical block-chain implementation using Akka and Scala

The name is a bit on the pun, since I forked this project off my previous naivechain-scala project.

Where naivechain is meant to be a simple as possible, cynical-chain tries to actually be useful by adding proof-of-work. This also means the code is more elaborate and tries to follow Scala best-practises.

It uses Akka and Akka-http. Peer to peer communication between nodes is straight akka remoting, and akka-http is used for a simple rest interface.

Nodes spin up a peer-to-peer network: connecting a node to another node will cause it to connect to all the nodes in the network.

Building, running, etc

The app can be run using docker-compose.

Start by building the docker container

sbt docker:publishLocal

Then run

docker-compose up

This will start 4 nodes, which will first connect to node1 (the seed node) and then proceed to build a P2P network.

Then mine a block:

curl -X POST -d "My data for the block" http://localhost:9000/mineBlock

All nodes should show the block:

curl http://localhost:9000/blocks
curl http://localhost:9001/blocks
curl http://localhost:9002/blocks
curl http://localhost:9003/blocks

Visualisation:

Open

ui/index.html

in your browser to visualse the blockchains. It will connect to localhost:9000 - localhost:9003 and show the chains, with the blocks coloured based on who found it.

Testing and code coverage

Code coverage is done using scoverage.

Run

sbt coverage test

to measure, and then

sbt coverageReport

to generate a report.