Simple Blockchain Service

Web service for a simple private Blockchain implemented using Node.js and Sails framework -- project @ Udacity's Blockchain Developer Nanodegree

Blockchain has the potential to change the way that the world approaches data. Develop Blockchain skills by understanding the data model behind Blockchain by developing your own simplified private blockchain.

                                                                                          (Getty Images)

Project Files

api/controllers/BlockController.js handles REST API endpoint. It includes as-is the implementation of simple private Blockchain from the previous project (https://github.com/NLKNguyen/simple-blockchain/blob/master/simpleChain.js)
config/routes.js connects the endpoints to the actions in the above controller.
The rest is scaffolding from Sails framework's new command with --no-frontend argument.

QuickStart with Docker

An example Docker container is created for easy deployment. This is only for not having to configure the development environment to test the code. The chain data, however, stays in the container; therefore, it will be lost when the container restart or shutdown. It is possible to set up the mount point for persisting the chain data outside of the container life cycle, but it is not the current focus of the project.

Require Docker to be installed on your system (prefer version 18.06.1 or later)

A pre-built Docker image is located at https://hub.docker.com/r/nlknguyen/simple-blockchain-service/

Run the container

$ docker run -p 8000:8000 --rm -it nlknguyen/simple-blockchain-service

The web service should be available at your localhost:8000

Shell login

Should you need to poke around the project environment inside the container, you can login to the shell:

$ docker run -p 8000:8000 --rm -it nlknguyen/simple-blockchain-service ash

When in there, you can start the web service manually:

$ node app

Rebuild

In case you need to modify the source code, after doing so, you can rebuild the image locally using the provided Dockerfile in the project tree. For sanity, only the source code is copied over to the image and npm install happens inside the image to provide a clean build every time.

$ docker build -t myblockchain .

Run your modified project:

$ docker run -p 8000:8000 --rm -it myblockchain

Manual Setup

This requires your system to have Node.js installed and be able to build (if needed) the libraries used in the project, e.g. leveldb

Install

$ npm install

Run

$ node app

Default port: 8000 (i.e. localhost:8000)

RESTful API Endpoint

Get Block

Get a block in the Blockchain at a given height

Method: GET

URL: /block/:blockHeight

Example:

localhost:1337/block/0

Success Response

Code: 200 OK
Content: JSON object of the block

Example

{
  "hash": "bcd909fe7d5a53ed7fe482606639cccc4c918b876d91a58733bf0a9db7bb502a",
  "height": 0,
  "body": "First block in the chain - Genesis block",
  "time": "1538884710",
  "previousBlockHash": ""
}

Error Response

Code: 404 Not Found

Add Block

Add a new block with string data to the Blockchain

Method: POST

URL: /block

Data:

key: body
value: string