0dns

This service is responsible for connecting to the network and fetching all the magic blocks from the network which are saved in the DB. There is a Network API which can be used to get latest set of miners and sharders for the network using the magic block.

Table of Contents

• Setup
• Buildding and starting the node
• Point to another blockchain
• Exposed APIs
• Config changes
• Cleanup
• Network issue

Setup

Clone the repo and run the following command inside the cloned directory

$ ./docker.local/bin/init.sh

Building and Starting the Node

If there is new code, do a git pull and run the following command

$ ./docker.local/bin/build.sh

Go to the bin directory (cd docker.local/bin) and run the container using

$ ./start.sh

Point to another blockchain

You can point the server to any instance of 0chain blockchain you like, Just go to config (docker.local/config) and update the magic_block.json.

By default they are pointing to local network with 4 miners and 1 sharder

You have to get the magic block from the chain you want to connect and update the magic_block.json file.

It will use that file to extract miners and sharders value and use that for further operations.

Exposed APIs

0dns exposes:

Network API

{BASEURL}/network

This API can be used to fetch the latest set of miners and sharder to connect. GoSDK will also uses this API to fetch miner/sharders value on runtime.

Details: https://0chain.net/page-documentation.html#tag/BlockWorker/paths/~1network/get

Magic Block API

{BASEURL}/magic_block

This API can be used to fetch the latest magic block data from network.

Details: https://0chain.net/page-documentation.html#tag/BlockWorker/paths/~1magic_block/get

Config Changes

You can do other config changes as well in 0dns.yaml file itself, Like

• Mongo DB connection URL, DB name and pool size

mongo:
  url: mongodb://mongodb:27017
  db_name: block-recorder
  pool_size: 2

• Server port

port: 9091

• Logging info level

logging:
  level: "info"
  console: false # printing log to console is only supported in development mode

• Worker related config

worker:
  magic_block_worker: 5 # in seconds, Frequency to update magic block

Cleanup

Get rid of old data when the blockchain is restarted or if you point to a different network:

$ ./docker.local/bin/clean.sh

Network issue

If there is no test network, run the following command

docker network create --driver=bridge --subnet=198.18.0.0/15 --gateway=198.18.0.255 testnet0

Troubleshooting

1. When running locally, if http://localhost:9091/network is returning below. Some commands might fail.

{
  "miners": [
    "https://198.18.0.71/",
    "https://198.18.0.72/",
    "https://198.18.0.74/",
    "https://198.18.0.73/"
  ],
  "sharders": [
    "https://198.18.0.81/"
  ]
}

To fix the miner and sharder URLs so it works locally, update docker.local/config/0dns.yaml to disable both use_https and use_path (set to false).