Building a Private Ethereum Network with Geth and BlockScout Explorer

Introduction

When stepping into blockchain development, deploying a private Ethereum network is often the most efficient way to conduct testing and development. A private chain offers security, convenience, and unlimited access to test Ether once mining is enabled.

This guide walks you through setting up a private Ethereum network using Geth (Go Ethereum) and exploring it via the open-source BlockScout blockchain explorer—all deployed via Docker for cross-platform compatibility.

Prerequisites

Docker: Ensure Docker is installed (Get Docker).

Setting Up the Private Chain

1. Launching the Geth Node

We’ll use an ubuntu:20.04 Docker container to run the Geth client:

docker run -d -it --name ethereum --hostname ethereum --network host ubuntu:20.04

Access the container:

docker exec -it ethereum bash

2. Installing Geth

Install Geth inside the container:

apt update && apt upgrade -y
apt install software-properties-common vim -y
add-apt-repository -y ppa:ethereum/ethereum
apt update && apt install ethereum -y

3. Configuring the Private Chain

Create a Data Directory:

mkdir /data

Generate a New Account (for mining rewards):

geth --datadir /data account new

Note the generated public address (e.g., 0x01461FB75c23ca5a061758120cb085C5100AB122).

Genesis File Setup:

Create /data/genesis.json with the following content:

{
  "config": {
    "chainId": 9,
    "homesteadBlock": 0,
    "eip150Block": 0,
    "eip155Block": 0,
    "eip158Block": 0,
    "byzantiumBlock": 0,
    "constantinopleBlock": 0,
    "petersburgBlock": 0,
    "istanbulBlock": 0
  },
  "alloc": {},
  "coinbase": "0x0000000000000000000000000000000000000000",
  "difficulty": "0x20000",
  "extraData": "",
  "gasLimit": "0x2fefd8",
  "nonce": "0x0000000000000042",
  "mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000",
  "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
  "timestamp": "0x00"
}

Initialize the chain:

geth --nousb --datadir /data init /data/genesis.json

Run Geth with Mining Enabled:

Create /data/run.sh:

geth --snapshot=false \
  --identity "localdevnet" \
  --networkid 9 \
  --datadir /data \
  --cache 2048 \
  --allow-insecure-unlock \
  --gcmode=archive \
  --syncmode=full \
  --mine \
  --miner.threads=1 \
  --miner.etherbase=0x01461FB75c23ca5a061758120cb085C5100AB122 \
  --http \
  --http.addr 0.0.0.0 \
  --http.port 24236 \
  --http.corsdomain "*" \
  --ws \
  --ws.addr 0.0.0.0 \
  --ws.port 12412 \
  --ws.api txpool,web3,eth,debug,ethash,net \
  --http.api txpool,web3,eth,debug,ethash,net \
  --ws.origins "*" >> /data/geth.log 2>&1

Start Geth in the background:

nohup /bin/bash /data/run.sh &

Monitor logs:

tail -f /data/geth.log

Look for mined potential block to confirm mining is active.

Interact via Geth Console:

geth attach /data/geth.ipc
> eth.accounts
> eth.getBalance(eth.accounts[0])

Alternative: Docker-Compose Setup

For a streamlined deployment, use this docker-compose.yml:

version: "3.9"
services:
  ethereum:
    image: ethereum/client-go:stable
    container_name: ethereum
    restart: always
    network_mode: host
    volumes: [ "./data:/data" ]
    entrypoint: /bin/sh
    command: /data/scripts/docker-entrypoint.sh

Deploying BlockScout Explorer

1. Clone the Repository:

mkdir ~/deploy && cd ~/deploy
git clone https://github.com/blockscout/blockscout

2. Start BlockScout:

cd blockscout/docker
COIN=ETH \
ETHEREUM_JSONRPC_VARIANT=geth \
ETHEREUM_JSONRPC_HTTP_URL=http://localhost:24236 \
ETHEREUM_JSONRPC_WS_URL=ws://localhost:12412 \
BLOCK_TRANSFORMER=base \
NETWORK=Ethereum \
SUBNETWORK=ETH \
make start

Note: For PoA chains (e.g., Clique), set BLOCK_TRANSFORMER=clique.

Access the explorer at http://localhost:4000.

FAQs

1. How do I troubleshoot Geth sync issues?

Ensure ports 24236 (HTTP) and 12412 (WS) are open. Check logs with tail -f /data/geth.log.

2. Can I change the mining reward address?

Yes. Update --miner.etherbase in /data/run.sh with a new address.

3. Why is BlockScout slow to load blocks?

The initial sync may take time. Ensure your node is fully synced (eth.syncing returns false in the Geth console).

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References


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