fabric的test-network

fabric原始碼包提供1個測驗案例目錄test-network，見下圖，

在該目錄中，執行./network.sh createChannel -c mychannel，將啟動1個網路，創建名為mychannel的通道，

在這個網路中，存在peer0.org1.example.com、peer0.org2.example.com、orderer.example.com共3個節點，

配置/etc/hosts

配置/etc/hosts的目的，是讓另1個終端SDK程式能夠訪問到3個節點：peer0.org1.example.com、peer0.org2.example.com、orderer.example.com，
使用docker exec -it peer0.org1.example.com /bin/ash進入其中1個節點，

在peer0.org1的節點中執行ping peer0.org1.example.com，獲得該節點的IP地址，類似地，獲得其他2個節點的IP地址，

另開1個終端，修改/etc/hosts檔案如下，并確認，這個終端，與上述3個節點的網路是相通的，

用Go撰寫SDK案例，訪問上面的網路

新建1個目錄queryChannel，這個案例用來查詢網路中已經創建的通道名稱，在這個目錄中，新建2個檔案e2e.yaml和queryChannel.go，
組態檔e2e.yaml內容如下，

version: 1.0.0
client:
  organization: Org1
  logging:
    level: info
  cryptoconfig:
    path: /root/go/src/github.com/hyperledger/fabric/scripts/fabric-samples/test-network/organizations
  credentialStore:
    path: "/tmp/state-store"
    cryptoStore:
      path: /tmp/msp
  tlsCerts:
    client:
      key:
        path: /root/go/src/github.com/hyperledger/fabric/scripts/fabric-samples/test-network/organizations/peerOrganizations/org1.example.com/users/User1@org1.example.com/tls/client.key
      cert:
        path: /root/go/src/github.com/hyperledger/fabric/scripts/fabric-samples/test-network/organizations/peerOrganizations/org1.example.com/users/User1@org1.example.com/tls/client.crt
        
organizations:
  Org1:
    mspid: Org1MSP
    cryptoPath:  peerOrganizations/org1.example.com/users/{username}@org1.example.com/msp
    peers:
      - peer0.org1.example.com

peers:
  peer0.org1.example.com:
    url: peer0.org1.example.com:7051
    tlsCACerts:
      path: /root/go/src/github.com/hyperledger/fabric/scripts/fabric-samples/test-network/organizations/peerOrganizations/org1.example.com/tlsca/tlsca.org1.example.com-cert.pem

SDK程式queryChannel.go的內容如下，

package main

import (
	"log"
	"strings"

	"github.com/hyperledger/fabric-sdk-go/pkg/client/resmgmt"
	"github.com/hyperledger/fabric-sdk-go/pkg/common/errors/retry"
	"github.com/hyperledger/fabric-sdk-go/pkg/common/providers/core"
	"github.com/hyperledger/fabric-sdk-go/pkg/common/providers/fab"
	"github.com/hyperledger/fabric-sdk-go/pkg/core/config"
	"github.com/hyperledger/fabric-sdk-go/pkg/core/config/lookup"
	"github.com/hyperledger/fabric-sdk-go/pkg/fabsdk"
	"github.com/pkg/errors"
)

const (
	orgName  = "Org1"
	orgAdmin = "Admin"
)

func main() {
	configPath := "./e2e.yaml"
	configProvider := config.FromFile(configPath)
	sdk, err := fabsdk.New(configProvider)
	if err != nil {
		log.Fatalf("Failed to create new SDK: %s", err)
	}
	defer sdk.Close()
	queryChannel(sdk)
}

func queryChannel(sdk *fabsdk.FabricSDK) {
	configBackend, err := sdk.Config()
	if err != nil {
		log.Fatalf("Failed to get config backend from SDK: %s", err)
	}
	targets, err := orgTargetPeers([]string{orgName}, configBackend)
	if err != nil {
		log.Fatalf("creating peers failed: %s", err)
	}

	clientContext := sdk.Context(fabsdk.WithUser("User1"), fabsdk.WithOrg("Org1"))
	resMgmtClient, err := resmgmt.New(clientContext)
	if err != nil {
		log.Fatalf("failed to query channel management client:%s", err)
	}
	channelQueryResponse, err := resMgmtClient.QueryChannels(
		resmgmt.WithTargetEndpoints(targets[0]), resmgmt.WithRetry(retry.DefaultResMgmtOpts))
	if err != nil {
		log.Fatalf("QueryChannels return error: %s", err)
	}
	for _, channel := range channelQueryResponse.Channels {
		log.Printf("***  Channel :%s\n", channel.ChannelId)
	}
}

func orgTargetPeers(orgs []string, configBackend ...core.ConfigBackend) ([]string, error) {
	networkConfig := fab.NetworkConfig{}
	err := lookup.New(configBackend...).UnmarshalKey("organizations", &networkConfig.Organizations)
	if err != nil {
		return nil, errors.WithMessage(err, "failed to get organizations from config ")
	}

	var peers []string
	for _, org := range orgs {
		orgConfig, ok := networkConfig.Organizations[strings.ToLower(org)]
		if !ok {
			continue
		}
		peers = append(peers, orgConfig.Peers...)
	}
	return peers, nil
}

執行go mod init .初始化該案例，會下載一些依賴包，

執行go run . ，運行這個SDK案例程式，在指定網路中查詢并輸出已經安裝的通道名稱，