Connect to Ethereum IPC using Ruby

To make things easier, I’m using the same ethereum-rb docker image as my node. It is configured to run Ruby developments environment too. So I don’t need to do any configurations in my personal computer to start Ethereum node. This is the docker-compose file I am using with the configurations.

docker-compose.yml

version: '2'

services:
  app:
    build: ./app
    command: --rinkeby --rpcapi "db,personal,eth,net,web3" --rpccorsdomain='*' --rpc --rpcaddr="0.0.0.0"
    volumes:
      - $HOME/.rinkeby:/root
      - ./app:/app

So you can have a folder app which contains my Dockerfile & pass command parameters to the ethereum node. By passing --rinkeby you can connect to the ethereum rinkeby test network & skip the main network for testing. And also you should have a volume to store the blockchain in local otherwise all the syncronized blocks will be gone after you stop the docker container.

And my Dockerfile is inside app folder.

Dockerfile

FROM dilumn/ethereum-rb
MAINTAINER Dilum Navanjana <dilumn@bbytes.sg>

You don’t need to do any configuration in the Dockerfile because all the configurations are done in docker-compose.yml.

Then you can build & run your ethereum node which is connecting to rinkeby network in my example.

docker-compose build
docker-compose -f docker-compose.yml up

By running these two commands you can see the ethereum node start syncronizing the blocks & at first it will take few hours to finish the syncronization.

There are two ways to connect to a ethereum node from outside. One is IPC & other one is using HTTP. I will write a separate blog post about the HTTP connection.

Because the Ethereum node is running inside a docker container, to connect using IPC you have to bash into the container first.

docker exec -it CONTAINERNAME bash

I created a Ruby gem elchapo which makes everyone easy to connect to Ethereum nodes using IPC.

To connect to the Ethereum node,

require 'elchapo'

client = Ethereum::Connection.new("/root/.ethereum/rinkeby/geth.ipc")

You have to make sure the .ipc file path is correct, otherwise you will not be able to connect to Ethereum node. Inside the docker container /root/.ethereum/rinkeby/geth.ipc is the file path for the ipc. If you are using any other configuration find the ipc file first of all.

After you create the connection client, you can use all these Ethereum eth commands & call those methods.

https://github.com/ethereum/wiki/wiki/JSON-RPC

https://github.com/ethereum/go-ethereum/wiki/Management-APIs

client.eth_accounts

Make sure you are using underscore instead of capitals. Eg: getBalance => get_balance

client.get_balance("ACCOUNT NUMBER")

That’s how you can connect to Ethereum node using IPC & execute geth commands in Ruby.

Cheers,

DilumN

Dilum Navanjana

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