Ethereum: Deploy on a Private Blockchain

 

 07 Mar 2017, 19:20 by CodeOoze

• truffle, geth, and private blockchains
  • Previously…
  • Install geth
  • Initialise the private blockchain with the genesis block
  • Start a node with geth
  • Prepare to deploy a contract using truffle
• Troubleshooting
  • Problem: No default account
  • Problem: Account is locked
  • Problem: RPC not started on node correctly
  • Problem: truffle migrate seems to hang at “Deploying Migrations…”

truffle, geth, and private blockchains

A brief introduction to deploying smart contracts on a private blockchain with truffle and geth.

Previously we went through setting up an Ethereum development environment with truffle and testrpc, and deploying a simple smart contract written in Solidity. Now we will take it a step further using truffle and geth to deploy a smart contract on a private blockchain. First, we will use geth to start a single node running locally on Ubuntu, then we’ll use truffle to deploy our smart contract.

For these steps I’m running Ubuntu 16 in VirtualBox on Windows 10, as described here.

Previously…

Check out these previous articles which describe setting up the dev environment and other tools I’ll be using:

• Windows 10: Install Ubuntu 16 in VirtualBox
• Ethereum: Setting up a development environment
• Ethereum: Intro to Smart Contracts with Solidity and Truffle

If you’re using Atom on Windows 10, the following articles may be useful for editing files on a remote Ubuntu server:

• Atom: Using remote-atom in Windows 10 - great for editing individual files
• Atom: Using remote-sync in Windows 10 - great for working with projects or directories with many files

Install geth

First we need to install geth on our Ubuntu machine. These steps are from the documentation: https://github.com/ethereum/go-ethereum/wiki/Installation-Instructions-for-Ubuntu

sudo apt-get install software-properties-common
sudo add-apt-repository -y ppa:ethereum/ethereum
sudo apt-get update
sudo apt-get install ethereum

That’s the basic geth install done.

Initialise the private blockchain with the genesis block

Next we need to initialise the private blockchain with a genesis block.

The article article at the link below has a good explanation of this process. The geth steps are a bit out of date, but the surrounding explanations are still valuable.

https://souptacular.gitbooks.io/ethereum-tutorials-and-tips-by-hudson/content/private-chain.html

Let’s go through it quickly:

1. Create a new directory to work from, then create the genesis.json file.

   mkdir geth && cd geth
   mkdir privchain
   touch genesis.json
   

2. Edit the genesis.json file and type or paste the following:

   {
       "nonce": "0x0000000000220042",
       "timestamp": "0x0",
       "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
       "extraData": "0x0",
       "gasLimit": "0x8000000",
       "difficulty": "0x400",
       "mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000",
       "coinbase": "0x3333333333333333333333333333333333333333",
       "alloc": {
       }
   }
   

   Now we’re ready to initialise the blockchain. Note that some of the tools we’re using are bleeding edge, and evolving quickly. As a result, information quickly goes out of date. I found this guide very useful and it seems current at the time of writing: http://mlgblockchain.com/ethereum-private-network.html

3. To initialise the blockchain. open a new terminal and enter

   geth --datadir privchain init genesis.json
   

   Output:

   ...WARNING: No etherbase set and no accounts found as default
   ...Allotted 128MB cache and 1024 file handles to /home/someone/privchain/geth/chaindata
   ...closed db:/home/someone/privchain/geth/chaindata
   ...Allotted 128MB cache and 1024 file handles to /home/someone/privchain/geth/chaindata
   ...successfully wrote genesis block and/or chain rule set: 6650a0ac6c5e805475...
   

   This should generate a new folder privchain with stuff inside it.

Start a node with geth

Next we use geth to start the first node on our private network. Since this is a private blockchain, it will be the only node for now.

1. Type the following to start the node using the initialised genesis block:

   geth --port 3000 --networkid 58342 --nodiscover --datadir="privchain" --maxpeers=0 --autodag \
        --rpc --rpcport 8545 --rpcaddr 127.0.0.1 --rpccorsdomain "*" --rpcapi "eth,net,web3" \
        --ipcapi "eth,net,web3"
   

   --rpcapi "eth,net,web3" is required for geth attach to work (we’ll use this shortly)

   --rpcport 8545 is to be consistent with ethereumjs-testrpc, and make integration with truffleeasier

   --rpcapi "eth,net,web3" is required for web3 to work in truffle

   Read more about the geth command line options here: https://github.com/ethereum/go-ethereum/wiki/Command-Line-Options

   After starting the geth node you should see something like IPC endpoint opened: /home/someone/privchain/geth.ipc

2. Next we attach to the geth console. Open a new terminal window and type:

   geth attach ipc://home/someone/privchain/geth.ipc
   

3. Then create an account to use

   > personal.newAccount('password')
   

4. Lastly, verify the new account is your default.

   > personal.listAccounts
   > web3.eth.coinbase
   

   These two commands should both return the same address, which should match the account created in the previous step.

Prepare to deploy a contract using truffle

For this step I’ll assume you already have a truffle project with a contract you’d like to deploy (if not, check out my earlier article). Before we can actually deploy the contract, there are a few things we need to do first (these are the sorts of things testrpc usally takes care of for us).

1. If we were to open a new terminal, cd to our truffle project, and run truffle migrate, we’d probably get an error:

   Deploying Migrations...
   Error encountered, bailing. Network state unknown. Review successful transactions manually.
   Error: authentication needed: password or unlock
   

   We need to unlock the account so truffle can deploy the contract. Refer also http://ethereum.stackexchange.com/questions/11908/account-is-locked-after-running-truffle-migrate-command

2. In the geth console, enter the following to unlock the default account, ensuring to replace password with the value entered when the account was created previously.

   > personal.unlockAccount(web3.eth.coinbase, "password", 15000)
   

   But still, if we were to run truffle compile again, we’d probably get another error:

   Deploying Migrations...
   Error encountered, bailing. Network state unknown. Review successful transactions manually.
   Error: Insufficient funds for gas * price + value
   

3. We seem to be making progress, and this error indicates we don’t have any ether at our default address. We can start mining briefly on our private network to create some Ether. Type the following into the geth console.

   > miner.start()
   

   Now back in the first terminal, where we started the geth node, you should start to see output like:

   Generating DAG for epoch 0 (size 1073739904) (000000000000000000000000000000000000000...)
   ...Generating DAG: 0%
   ...Generating DAG: 1%
   ...Generating DAG: 2%
   

   This could take a while to run, but you can pass the time by reading about the DAG:

   • https://github.com/ethereum/wiki/wiki/Mining
   • https://github.com/ethereum/wiki/wiki/Ethash-DAG

   Also note that if you’re running your geth node for extended periods of time, i.e longer than 30000 blocks, using --autodag to enable automatic DAG pregeneration can help speed things up.

4. Eventually you’ll see the mining start:

   ...Generating DAG: 100%
   ...Done generating DAG for epoch 0, it took 8m16.297777249s
   ...