區塊鏈學習（二）以太坊私有鏈搭建

通過一段時間關於以太坊的學習，博主也算是對區塊鏈以及以太坊有了一個初步的瞭解，整理一篇關於以太坊搭建私有鏈的方法。

若想以太坊節點之間可以相互鏈接須要知足必定的條件：

1. 相同的協議版本
2. 相同的network id

搭建私有鏈最簡單的方式就是使用geth裏的 --network 選項，設置一個與主網不一樣的network id （以太坊主網id是1）

1、創建創世區塊

打開終端輸入如下命令

1 mkdir privatechain #創建文件夾，名字自擬
2 cd privatechain    #終端進入創建的文件夾

創建創世區塊文件genesis.json

1 vim genesis.json  #注：沒有安裝vim 能夠用 vi 命令

在創世區塊的json文件中填入如下內容：

 1 {
 2     "config": {
 3         "chainId": 20,
 4         "homesteadBlock": 0,
 5         "eip155Block": 0,
 6         "eip158Block": 0
 7     },
 8     "coinbase" : "0x0000000000000000000000000000000000000000",
 9     "difficulty" : "0x100",    #爲方便挖礦，咱們這裏將難度值設置的很小
10     "extraData" : "",
11     "gasLimit" : "0xffffffff",
12     "nonce" : "0x0000000000000042",
13     "mixhash" : "0x0000000000000000000000000000000000000000000000000000000000000000",
14     "parentHash" : "0x0000000000000000000000000000000000000000000000000000000000000000",
15     "timestamp" : "0x00",
16     "alloc": { }
17 }

各個參數的介紹

參數名稱	參數詳解
chainId	指定了獨立的區塊鏈網絡id，網絡id在鏈接到其它節點的時候會用到，以太坊公網id是1，不一樣的id網絡的節點沒法相互鏈接
homesteadBlock	HomesteadBlock是以太坊的第二個主要版本，第一個是Frontier，這個值設置爲「0」表示目前正在使用Homestead版本
eip155Block	eip是ethereum improvement proposal的縮寫，咱們的鏈不會提議分叉，因此設置爲「0」便可
eip158Block	eip是ethereum improvement proposal的縮寫，咱們的鏈不會提議分叉，因此設置爲「0」便可
coinbase	礦工的帳號（隨便填）
difficulty	設置當前區塊的難度，若是難度過大，cpu挖礦就很難，這裏設置較小難度
extraData	能夠寫入32byte大小的任意數據，每一個block都會有，由挖出block的miner來決定要不要寫點什麼
gasLimit	該值設置對gas的消耗總量限制，用來限制區塊能包含的交易信息和，由於咱們是私有鏈，因此填最大
nonce	一個用於挖礦的64位隨機數
mixhash	與nonce配合用於挖礦，由上一個區塊的一部分生成的哈希，注意它和nonce的設置須要知足以太坊的yellow paper
parentHash	上一個區塊的哈希值，由於是創世區塊，因此這個值是0
timestamp	設置創世區塊的時間戳
alloc	給某個帳戶預分配以太幣

2、初始化創世節點，而且設置data目錄

在privatechain目錄終端下輸入以下命令

1 geth --datadir ./data/00 init genesis.json
2 
3 #--datadir data 中data是文件夾的名稱，私有鏈的數據會存儲在這個文件夾內。若存在其餘節點文件名要不一樣。能夠經過「--datadir 文件名」來區分不一樣的私有鏈節點，若沒有設置--datadir，則會讀取以太坊主網的數據，默認位置在/root/.ethereum

出現以日誌說明初始化成功

INFO [06-26|21:02:01.682] Maximum peer count                       ETH=25 LES=0 total=25
INFO [06-26|21:02:01.697] Allocated cache and file handles         database=/home/milo/private-geth/data/00/geth/chaindata cache=16 handles=16
INFO [06-26|21:02:01.866] Writing custom genesis block 
INFO [06-26|21:02:01.866] Persisted trie from memory database      nodes=0 size=0.00B time=4.212µs gcnodes=0 gcsize=0.00B gctime=0s livenodes=1 livesize=0.00B
INFO [06-26|21:02:01.867] Successfully wrote genesis state         database=chaindata                                      hash=696bed…1d07ed
INFO [06-26|21:02:01.867] Allocated cache and file handles         database=/home/milo/private-geth/data/00/geth/lightchaindata cache=16 handles=16
INFO [06-26|21:02:01.956] Writing custom genesis block 
INFO [06-26|21:02:01.956] Persisted trie from memory database      nodes=0 size=0.00B time=3.013µs gcnodes=0 gcsize=0.00B gctime=0s livenodes=1 livesize=0.00B
INFO [06-26|21:02:01.957] Successfully wrote genesis state         database=lightchaindata                                      hash=696bed…1d07ed

3、啓動節點

1 geth --datadir ./data/00 --networkid 100 console
2 #100爲network id，1爲主網id，能夠選擇除1之外的隨機數 

milo@milo-K46CB:~/private-geth$ tree
終端輸入tree，查看生成的目錄
.
├── data
│   └── 00
│       ├── geth
│       │   ├── chaindata
│       │   │   ├── 000002.ldb
│       │   │   ├── 000003.log
│       │   │   ├── CURRENT
│       │   │   ├── CURRENT.bak
│       │   │   ├── LOCK
│       │   │   ├── LOG
│       │   │   └── MANIFEST-000004
│       │   ├── lightchaindata
│       │   │   ├── 000001.log
│       │   │   ├── CURRENT
│       │   │   ├── LOCK
│       │   │   ├── LOG
│       │   │   └── MANIFEST-000000
│       │   ├── LOCK
│       │   ├── nodekey
│       │   ├── nodes
│       │   │   ├── 000001.log
│       │   │   ├── CURRENT
│       │   │   ├── LOCK
│       │   │   ├── LOG
│       │   │   └── MANIFEST-000000
│       │   └── transactions.rlp
│       ├── geth.ipc
│       └── keystore
│           └── UTC--2019-06-26T13-02-31.335901324Z--8830397771710ade101f0080f0da076181bad374
└── genesis.json

INFO [06-26|21:02:06.602] Maximum peer count                       ETH=25 LES=0 total=25
INFO [06-26|21:02:06.604] Starting peer-to-peer node               instance=Geth/v1.8.27-stable-4bcc0a37/linux-amd64/go1.10.4
INFO [06-26|21:02:06.604] Allocated cache and file handles         database=/home/milo/private-geth/data/00/geth/chaindata cache=512 handles=2048
INFO [06-26|21:02:06.792] Initialised chain configuration          config="{ChainID: 15 Homestead: 0 DAO: <nil> DAOSupport: false EIP150: <nil> EIP155: 0 EIP158: 0 Byzantium: <nil> Constantinople: <nil>  ConstantinopleFix: <nil> Engine: unknown}"
INFO [06-26|21:02:06.792] Disk storage enabled for ethash caches   dir=/home/milo/private-geth/data/00/geth/ethash count=3
INFO [06-26|21:02:06.792] Disk storage enabled for ethash DAGs     dir=/home/milo/.ethash                          count=2
INFO [06-26|21:02:06.792] Initialising Ethereum protocol           versions="[63 62]" network=100
INFO [06-26|21:02:06.863] Loaded most recent local header          number=0 hash=696bed…1d07ed td=256 age=50y2mo1w
INFO [06-26|21:02:06.863] Loaded most recent local full block      number=0 hash=696bed…1d07ed td=256 age=50y2mo1w
INFO [06-26|21:02:06.863] Loaded most recent local fast block      number=0 hash=696bed…1d07ed td=256 age=50y2mo1w
INFO [06-26|21:02:06.863] Regenerated local transaction journal    transactions=0 accounts=0
INFO [06-26|21:02:07.009] New local node record                    seq=1 id=1b933112e1333f9a ip=127.0.0.1 udp=30303 tcp=30303
INFO [06-26|21:02:07.015] Started P2P networking                   self=enode://bfad31051f4ba04bf5bbb2fdd455bfcbf924479991b029a8604ab5abb386431b7c7f7d1edbba0bf6db66ad172b632ca45518239979634f190a0c26c0a9b9864b@127.0.0.1:30303
INFO [06-26|21:02:07.016] IPC endpoint opened                      url=/home/milo/private-geth/data/00/geth.ipc
Welcome to the Geth JavaScript console!

instance: Geth/v1.8.27-stable-4bcc0a37/linux-amd64/go1.10.4
 modules: admin:1.0 debug:1.0 eth:1.0 ethash:1.0 miner:1.0 net:1.0 personal:1.0 rpc:1.0 txpool:1.0 web3:1.0

>

出現這樣的日誌說明私有網絡就搭建成功了，下一步咱們來在這個私有網絡挖礦。

4、挖礦

要挖礦首先必需要有一個帳戶，根據如下命令。

> eth.accounts     #查看node中的全部帳戶
[]
##輸出了一個「[]」，說明沒有帳戶
> personal.newAccount("123456")      
##建立新帳戶，123456是帳戶密碼，通常會輸出如下結果
"0x8830397771710ade101f0080f0da076181bad374"
> eth.accounts
["0x8830397771710ade101f0080f0da076181bad374"]
此時帳戶已經有了，咱們能夠進行挖礦了，輸入以ixa命令
> miner.start(3)    
##miner.start()是啓動挖礦，3是啓動線程數，爲避免影響電腦性能，這裏咱們就用3線程

到這裏時會出現一些問題，通常來講，第一次啓動挖礦，應當會出現如下日誌

INFO [05-16|00:07:25] Updated mining threads                   threads=0
INFO [05-16|00:07:25] Starting mining operation
null
INFO [05-16|00:07:25] Commit new mining work                   number=1 txs=0 uncles=0 elapsed=38.053ms
INFO [05-16|00:07:28] Generating DAG in progress               epoch=0 percentage=0 elapsed=1.715
INFO [05-16|00:07:30] Generating DAG in progress               epoch=0 percentage=1 elapsed=3.448s
INFO [05-16|00:07:31] Generating DAG in progress               epoch=0 percentage=2 elapsed=5.059s
INFO [05-16|00:07:33] Generating DAG in progress               epoch=0 percentage=3 elapsed=6.799s
INFO [05-16|00:07:35] Generating DAG in progress               epoch=0 percentage=4 elapsed=8.373s
##當percentage=100時，也就是加載到100%時，會開始挖礦，這個過程可能會比較慢，要耐心等待。
INFO [06-26|21:10:53.002] Successfully sealed new block            number=1 sealhash=dac366…ad5c8d hash=3cb840…442e46 elapsed=8m9.375s
INFO [06-26|21:10:53.042] 🔨 mined potential block                  number=1 hash=3cb840…442e46
INFO [06-26|21:10:53.103] Commit new mining work                   number=2 sealhash=088254…66c59d uncles=0 txs=0 gas=0 fees=0 elapsed=60.592ms
INFO [06-26|21:10:53.906] Successfully sealed new block            number=2 sealhash=088254…66c59d hash=446602…93d76b elapsed=803.002ms
INFO [06-26|21:10:53.906] 🔨 mined potential block                  number=2 hash=446602…93d76b
INFO [06-26|21:10:53.906] Commit new mining work                   number=3 sealhash=6c39db…66d2bf uncles=0 txs=0 gas=0 fees=0 elapsed=178.137µs
INFO [06-26|21:10:54.406] Successfully sealed new block            number=3 sealhash=6c39db…66d2bf hash=fa550b…95d423 elapsed=500.446ms
INFO [06-26|21:10:54.407] 🔨 mined potential block                  number=3 hash=fa550b…95d423
##這個就是表明挖到礦了

正常來說，第一次搭建私有鏈到這裏都沒什麼問題，而當我第二次開啓節點挖礦時出現了問題

> miner.start(3)
INFO [06-26|21:02:43.616] Updated mining threads                   threads=3
INFO [06-26|21:02:43.626] Transaction pool price threshold updated price=1000000000
INFO [06-26|21:02:43.627] Etherbase automatically configured       address=0x8830397771710ADE101f0080f0da076181Bad374
null
> INFO [06-26|21:02:43.627] Commit new mining work                   number=1 sealhash=dac366…ad5c8d uncles=0 txs=0 gas=0 fees=0 elapsed=373.028µs
##當我再次輸入挖礦命令時，狀況陷入了僵局，此時會一直停留在Commit new mining work
##我在網上搜索過許多，大多沒有解決辦法，也沒有指出問題的緣由，反反覆覆試過不少次，自第一次搭建私有鏈後，後續的都一直是這樣。
##因此我打算在另外一臺電腦上安裝虛擬機，從新再來一遍試試，而這個我也一直放着一直加載。
##當我在通過一系列猛如虎的操做下，裝虛擬機，裝ethereum開發環境，終於也到了加載DGA的那一步
##這時再看一直僵在Commit new mining work的電腦時，它忽然開始挖礦了。。。。。
##因此到這個步驟時，並非什麼錯誤，咱們應當耐心等待

> INFO [06-26|21:02:43.627] Commit new mining work                   number=1 sealhash=dac366…ad5c8d uncles=0 txs=0 gas=0 fees=0 elapsed=373.028µs
INFO [06-26|21:10:53.002] Successfully sealed new block            number=1 sealhash=dac366…ad5c8d hash=3cb840…442e46 elapsed=8m9.375s
INFO [06-26|21:10:53.042] 🔨 mined potential block                  number=1 hash=3cb840…442e46
INFO [06-26|21:10:53.103] Commit new mining work                   number=2 sealhash=088254…66c59d uncles=0 txs=0 gas=0 fees=0 elapsed=60.592ms
INFO [06-26|21:10:53.906] Successfully sealed new block            number=2 sealhash=088254…66c59d hash=446602…93d76b elapsed=803.002ms
INFO [06-26|21:10:53.906] 🔨 mined potential block                  number=2 hash=446602…93d76b
INFO [06-26|21:10:53.906] Commit new mining work                   number=3 sealhash=6c39db…66d2bf uncles=0 txs=0 gas=0 fees=0 elapsed=178.137µs
INFO [06-26|21:10:54.406] Successfully sealed new block            number=3 sealhash=6c39db…66d2bf hash=fa550b…95d423 elapsed=500.446ms
INFO [06-26|21:10:54.407] 🔨 mined potential block                  number=3 hash=fa550b…95d423
INFO [06-26|21:10:54.457] Commit new mining work                   number=4 sealhash=f170b2…be929e uncles=0 txs=0 gas=0 fees=0 elapsed=50.737ms
INFO [06-26|21:10:54.946] Successfully sealed new block            number=4 sealhash=f170b2…be929e hash=190e69…4fbc8b elapsed=488.870ms

查看挖到的區塊

1 > miner.stop()
2 null
3 > eth.getBalance(eth.accounts[0])
4 155000000000000000000
5 > eth.blockNumber
6 31

到這裏，一個基於以太坊的私有鏈就搭建完成了