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Ethereum: Up & Running

One of my recent jobs was to build a simple payment processor for Ethereum. The task was way simpler I thought it would be, but starting to work with Ethereum can be a little confusing. Unlike Bitcoin, there is not only one single monolithic component like Bitcoin Core to work with, but a few, like geth - the CLI for running a full Ethereum node, or mist, the wallet/browser for dapps.

Installing geth

geth is a golang app, and it is very simple to install:

$ cd /opt
$ git clone https://github.com/ethereum/go-ethereum.git
Cloning into 'go-ethereum'...
remote: Counting objects: 69307, done.
remote: Total 69307 (delta 0), reused 0 (delta 0), pack-reused 69307
Receiving objects: 100% (69307/69307), 95.20 MiB | 8.63 MiB/s, done.
Resolving deltas: 100% (46104/46104), done.
$ cd go-ethereum
$ make all
[...]
github.com/ethereum/go-ethereum/cmd/geth
github.com/ethereum/go-ethereum/cmd/swarm
github.com/ethereum/go-ethereum/cmd/wnode
$ ls -l build/bin/
total 270568
[...]
-rwxr-xr-x. 1 root root 37394152 Apr  1 09:09 geth
[...]
$

And you’re done. You can now launch geth to run a full Ethereum node on its main’s network, on testnet or even create your own private chain, because unlike Bitcoin, it is very easy to create your own private network.

Joining Ethereum main’s network

Nothing much to say, just run geth. That’s it.

$ /opt/go-ethereum/build/bin/geth 
INFO [04-01|09:17:02] Maximum peer count                       ETH=25 LES=0 total=25
INFO [04-01|09:17:02] Starting peer-to-peer node               instance=Geth/v1.8.4-unstable-a095b84e/linux-amd64/go1.10.1
INFO [04-01|09:17:02] Allocated cache and file handles         database=/home/mycroft/.ethereum/geth/chaindata cache=768 handles=512
INFO [04-01|09:17:02] Writing default main-net genesis block 
INFO [04-01|09:17:02] Persisted trie from memory database      nodes=12356 size=2.34mB time=37.468534ms gcnodes=0 gcsize=0.00B gctime=0s livenodes=1 livesize=0.00B
INFO [04-01|09:17:02] Initialised chain configuration          config="{ChainID: 1 Homestead: 1150000 DAO: 1920000 DAOSupport: true EIP150: 2463000 EIP155: 2675000 EIP158: 2675000 Byzantium: 4370000 Constantinople: <nil> Engine: ethash}"
INFO [04-01|09:17:02] Disk storage enabled for ethash caches   dir=/home/mycroft/.ethereum/geth/ethash count=3
INFO [04-01|09:17:02] Disk storage enabled for ethash DAGs     dir=/home/mycroft/.ethash               count=2
INFO [04-01|09:17:02] Initialising Ethereum protocol           versions="[63 62]" network=1
INFO [04-01|09:17:02] Loaded most recent local header          number=0 hash=d4e567…cb8fa3 td=17179869184
INFO [04-01|09:17:02] Loaded most recent local full block      number=0 hash=d4e567…cb8fa3 td=17179869184
INFO [04-01|09:17:02] Loaded most recent local fast block      number=0 hash=d4e567…cb8fa3 td=17179869184
INFO [04-01|09:17:02] Regenerated local transaction journal    transactions=0 accounts=0
INFO [04-01|09:17:02] Starting P2P networking 
INFO [04-01|09:17:04] UDP listener up                          self=enode://632f2cf51de6dafb0e1254177858069595706fde6b649fb7f4811f4a14066e8955a5407226a5f78463217527c40696846f6117e9297d3837882c823a11540e72@90.127.22.118:30303
INFO [04-01|09:17:04] RLPx listener up                         self=enode://632f2cf51de6dafb0e1254177858069595706fde6b649fb7f4811f4a14066e8955a5407226a5f78463217527c40696846f6117e9297d3837882c823a11540e72@90.127.22.118:30303
INFO [04-01|09:17:04] IPC endpoint opened                      url=/home/mycroft/.ethereum/geth.ipc
INFO [04-01|09:17:34] Block synchronisation started 
INFO [04-01|09:17:38] Imported new block headers               count=192 elapsed=894.468ms number=192 hash=723899…123390 ignored=0
INFO [04-01|09:17:38] Imported new block receipts              count=2   elapsed=127.337µs number=2   hash=b495a1…4698c9 size=8.00B  ignored=0
INFO [04-01|09:17:38] Imported new block headers               count=192 elapsed=17.487ms  number=384 hash=d3d5d5…c79cf3 ignored=0
INFO [04-01|09:17:38] Imported new state entries               count=523 elapsed=3.924µs   processed=523 pending=8366 retry=0 duplicate=0 unexpected=0
[...]

Now, you’ll have to wait. Also, Ethereum is very CPU and I/O consumming (you’ll need a SSD). If you don’t need it, I strongly advise not to run an full Ethereum node.

About Ethereum testnet

Contrary to Bitcoin, there is 3 Ethereum testnets: ropsten, kovan and rinkeby, and they are all differents from the others.

  • Ropsten:
    • Proof of work (you can mine coins);
    • Supported by geth and parity;
    • Reproduces the main net environment.
  • Rinkeby:
    • Proof of authority (can’t mine new coins);
    • Supported by geth only.
  • Kovan:
    • Proof of authority;
    • Not supported by geth.

Joining a testnet network is as simple as joining mainnet. Just start geth using the --testnet switch to join ropsten, or the --rinkeby switch to join rinkeby:

$ /opt/go-ethereum/build/bin/geth --rinkeby
INFO [04-01|09:27:53] Maximum peer count                       ETH=25 LES=0 total=25
INFO [04-01|09:27:53] Starting peer-to-peer node               instance=Geth/v1.8.4-unstable-a095b84e/linux-amd64/go1.10.1
INFO [04-01|09:27:53] Allocated cache and file handles         database=/home/mycroft/.ethereum/rinkeby/geth/chaindata cache=768 handles=512
INFO [04-01|09:27:53] Writing custom genesis block 
INFO [04-01|09:27:53] Persisted trie from memory database      nodes=355 size=65.27kB time=1.459688ms gcnodes=0 gcsize=0.00B gctime=0s livenodes=1 livesize=0.00B
INFO [04-01|09:27:53] Initialised chain configuration          config="{ChainID: 4 Homestead: 1 DAO: <nil> DAOSupport: true EIP150: 2 EIP155: 3 EIP158: 3 Byzantium: 1035301 Constantinople: <nil> Engine: clique}"
INFO [04-01|09:27:53] Initialising Ethereum protocol           versions="[63 62]" network=4                                           
[...]

If you need coins on testnet networks, you can grab a few on the existing faucets. There is one for ropsten and one for rinkeby.

And what’s up with private chains ?

With Ethereum, you can create your own chain without having to patch source code, like Bitcoin. You just need a genesis file, a JSON configuration file that describes your chain.

Lets take a look at my last genesis.json file:

{
    "config": {
        "chainId": 2283526326,
        "homesteadBlock": 0,
        "eip155Block": 0,
        "eip158Block": 0
    },
    "difficulty": "0x200",
    "gasLimit": "0x8000000",
    "alloc": {
        "c97ec1b4bf2b0106f951e113690b194289037d52": { "balance": "1000000000000000000000000" }
    }
}

Create your chain using geth init genesis.json

$ geth --datadir .ethereum/sweet-refrain init genesis.json 
INFO [04-01|09:39:08] Maximum peer count                       ETH=25 LES=0 total=25
INFO [04-01|09:39:08] Allocated cache and file handles         database=/home/mycroft/.ethereum/sweet-refrain/geth/chaindata cache=16 handles=16
INFO [04-01|09:39:08] Writing custom genesis block 
INFO [04-01|09:39:08] Persisted trie from memory database      nodes=1 size=202.00B time=33.404µs gcnodes=0 gcsize=0.00B gctime=0s livenodes=1 livesize=0.00B
INFO [04-01|09:39:08] Successfully wrote genesis state         database=chaindata                                            hash=e82409…14d6b1
INFO [04-01|09:39:08] Allocated cache and file handles         database=/home/mycroft/.ethereum/sweet-refrain/geth/lightchaindata cache=16 handles=16
INFO [04-01|09:39:08] Writing custom genesis block 
INFO [04-01|09:39:08] Persisted trie from memory database      nodes=1 size=202.00B time=24.128µs gcnodes=0 gcsize=0.00B gctime=0s livenodes=1 livesize=0.00B
INFO [04-01|09:39:08] Successfully wrote genesis state         database=lightchaindata                                            hash=e82409…14d6b1

And launch your daemon:

$ /opt/go-ethereum/build/bin/geth --datadir .ethereum/sweet-refrain
INFO [04-01|09:40:25] Maximum peer count                       ETH=25 LES=0 total=25
INFO [04-01|09:40:25] Starting peer-to-peer node               instance=Geth/v1.8.4-unstable-a095b84e/linux-amd64/go1.10.1
INFO [04-01|09:40:25] Allocated cache and file handles         database=/home/mycroft/.ethereum/sweet-refrain/geth/chaindata cache=768 handles=512
INFO [04-01|09:40:25] Initialised chain configuration          config="{ChainID: 2283526326 Homestead: 0 DAO: <nil> DAOSupport: false EIP150: <nil> EIP155: 0 EIP158: 0 Byzantium: <nil> Constantinople: <nil> Engine: unknown}"
INFO [04-01|09:40:25] Disk storage enabled for ethash caches   dir=/home/mycroft/.ethereum/sweet-refrain/geth/ethash count=3
INFO [04-01|09:40:25] Disk storage enabled for ethash DAGs     dir=/home/mycroft/.ethash                             count=2
INFO [04-01|09:40:25] Initialising Ethereum protocol           versions="[63 62]" network=1
INFO [04-01|09:40:25] Loaded most recent local header          number=0 hash=e82409…14d6b1 td=512
INFO [04-01|09:40:25] Loaded most recent local full block      number=0 hash=e82409…14d6b1 td=512
INFO [04-01|09:40:25] Loaded most recent local fast block      number=0 hash=e82409…14d6b1 td=512
INFO [04-01|09:40:25] Loaded local transaction journal         transactions=0 dropped=0
INFO [04-01|09:40:25] Regenerated local transaction journal    transactions=0 accounts=0
INFO [04-01|09:40:25] Starting P2P networking
INFO [04-01|09:40:27] UDP listener up                          self=enode://bac80bb4ca615dfbfbf8a738169ac72b47c7917a53941458981c4f09f3e1c0c98e940091acd12d66bff1927d4d44a26ee07814faf27c3f63b628ebc83e44e0ec@[::]:30303
INFO [04-01|09:40:27] RLPx listener up                         self=enode://bac80bb4ca615dfbfbf8a738169ac72b47c7917a53941458981c4f09f3e1c0c98e940091acd12d66bff1927d4d44a26ee07814faf27c3f63b628ebc83e44e0ec@[::]:30303
INFO [04-01|09:40:27] IPC endpoint opened                      url=/home/mycroft/.ethereum/sweet-refrain/geth.ipc

Your private chain is running !

You can attach the console and retrieve the coins allocated in the genesis block (in the alloc section), using our private key:

$ geth --datadir .ethereum/sweet-refrain attach
Welcome to the Geth JavaScript console!

instance: Geth/v1.8.4-unstable-a095b84e/linux-amd64/go1.10.1
 modules: admin:1.0 debug:1.0 eth:1.0 miner:1.0 net:1.0 personal:1.0 rpc:1.0 txpool:1.0 web3:1.0

> personal.importRawKey('f0abab15e15b43826a746c89ceb740ad28b0fc683475d696f5c17d924cdd9294', '');
"0xc97ec1b4bf2b0106f951e113690b194289037d52"
> eth.accounts
["0xc97ec1b4bf2b0106f951e113690b194289037d52"]
> web3.fromWei(eth.getBalance(eth.accounts[0]))
1000000
>

We can also mine new blocks. We need to set the Ether base before:

> miner.setEtherbase('c97ec1b4bf2b0106f951e113690b194289037d52')
true
> miner.start(1)
null
>

On first start, geth will generate the DAG (which will take a few seconds) and then will mien blocks:

INFO [04-01|09:58:32] Successfully sealed new block            number=1 hash=65c64d…60aa82          
INFO [04-01|09:58:32] 🔨 mined potential block                  number=1 hash=65c64d…60aa82         
INFO [04-01|09:58:32] Commit new mining work                   number=2 txs=0 uncles=0 elapsed=123.754µs

You’ll receive new coins in just a few seconds:

> web3.fromWei(eth.getBalance('c97ec1b4bf2b0106f951e113690b194289037d52'), 'ether');
1000035
>

The reference of APIs can be found on the Javascript API and Management APIs pages.

Bonus: sending & receiving coins

Let’s say now we want to send coins to another account. I’ll create for this another address, bob’s address, and I’ll send him 5000 coins.

Creating bob’s account

Use personal.newAccount to create a new account.

> personal.newAccount()
Passphrase: 
Repeat passphrase: 
"0x956dd1ec7e345ec5aed5d07938a239328e275b37"
> var bob = "0x956dd1ec7e345ec5aed5d07938a239328e275b37";
undefined
> web3.fromWei(eth.getBalance(bob))
0

Then, eth.sendTransaction to send coins.

> var me = eth.accounts[0];
undefined
> web3.fromWei(eth.getBalance(me))
1000035
> var amount = web3.toWei(5000, "ether");
undefined
> web3.personal.unlockAccount(me, '', 600)
true
> eth.sendTransaction({from: me, to: bob, value: amount});
"0xddc5f0120fd3642eef7ef8fb7e76339f002b97160911a926193d0ccf2bc44f98"

At this time, the transaction is created and in the network, but miner is off. We need to mine at least a block for bob to be able to retrieve its coins.

> miner.start(1)
null
INFO [04-01|10:19:23] Starting mining operation 
INFO [04-01|10:19:23] Commit new mining work                   number=8 txs=1 uncles=0 elapsed=454.946µs
INFO [04-01|10:19:25] Successfully sealed new block            number=8 hash=c43d9b…69d055
INFO [04-01|10:19:25] 🔨 mined potential block                  number=8 hash=c43d9b…69d055
INFO [04-01|10:19:25] Commit new mining work                   number=9 txs=0 uncles=0 elapsed=179.498µs
> miner.stop()
true

We mined a block, with one tx in it ! Let’s check balances:

> web3.fromWei(eth.getBalance(me))
995040
> web3.fromWei(eth.getBalance(bob))
5000
>

Bob correctly got the coins!

2018-04-01
https://mkz.me/weblog/posts/ethereum-up-and-running/ Patrick MARIE