Building Hyperledger Fabric Network for Blockchain Applications

1. Hyperledger Fabric Overview

   Hyperledger Fabric is an open source enterprise-grade platform that leverages a highly-modular and configurable architecture. Hyperledger Fabric is optimized for a broad range of industry use cases, including the finance, banking, healthcare, insurance, and public sectors, as well as supply chains and digital asset management. Here is a good article on why choosing Hyperledger Fabric over other blockchain development platforms. 

   For those who are not familiar with Hyperledger project Intro to Hyperledger Family and Hyperledger Blockchain Ecosystem, Hyperledger Design Philosophy and Framework Architecture, The Survey of Hyperledger Fabric Architecture and Components for Blockchain Developers and Overview of Building Blockchain Smart Contracts in Hyperledger articles are strongly recommended.
   Hyperledger Fabric supports Smart Contact development in general-purpose programming languages, such as JavaScript, Java, Go, and Node.js. Hyperledger Fabric is also operating under a governance model to build trust between participants on a shared network.
   In our previous recipe, we have successfully installed Hyperledger Fabric on an AWS EC2 virtual machine, in this recipe, we will set up the first Hyperledger Fabric network. To run this recipe, you need to complete the installation of Hyperledger Fabric with samples and binaries on the AWS EC2 instance. In this recipe, we cover the following:

   • Generating the crypto/certificate using cryptogen
   • Generating the configuration transaction using configtxgen
   • Bring up the nodes based on what is defined in the docker-compose file

   In our next recipe, we will work with Hyperledger Fabric CLI to set up network and manage chaincode. Specifically, we cover the following:

   • Using the CLI to set up the first network
   • Using the CLI to install and instantiate the chaincode
   • Using the CLI to invoke and query the chaincode

2. Build Hyperledger Fabric Network

   There is a Build your first network (BYFN) sample installed with Hyperledger Fabric. We will use that to provision a sample Hyperledger Fabric network that consists of two organizations, each maintaining two peer nodes, and a solo ordering service. To do this, follow these steps:

   1. Log in as a default user and execute the byfn.sh script to generate certificates and keys for the network:

   $ cd ~

   sudo chmod 777 -R fabric-samples

    cd fabric-samples/first-network

   sudo ./byfn.sh generate

    

   2. Bring up the Fabric network by executing the byfn.sh script using the up option:

   $ cd ~

   cd fabric-samples/first-network

    sudo ./byfn.sh up

   You should see the following output, which states that the network has started successfully:

    

    

   3. Bring down the Fabric network by executing the byfn.sh script using the down option to shut down and clean up the network. This kills the containers, removes the crypto material and artifacts, and deletes the chaincode images. The following code shows how to do this:

   $ cd ~

   cd fabric-samples/first-network 

   sudo ./byfn.sh down

   Let’s review the byfn.sh script, shown as follows. This script is well documented, and you should read about it in detail to understand each execution step during the network startup process:
   

    

   We will review and exam the Hyperledger Fabric byfn.sh script using the command-line interface.

   4. Use the tool for crypto and certificate generation, called cryptogen, which uses a YAML configuration file as the base to generate the certificates:

   OrdererOrgs:

   Name: Orderer

   Domain: example.com Specs:

   Hostname: orderer PeerOrgs:

   Name: Org1

   Domain: org1.example.com

   EnableNodeOUs: true Template:

   Count: 2 Users:

   Count: 1

   – Name: Org2

   Domain: org2.example.com

   EnableNodeOUs: true

   Template:

   Count: 2

   Users:

   Count: 1

   The following command will generate the YAML file:

   $ cd ~

   $ cd fabric-samples/first-network

   $ sudo ../bin/cryptogen generate –config=./crypto-config.yaml

   On execution of the previous command, you will find a new directory crypto-config is created, and inside there are directories that correspond to ordererOrganizations and peerOrganizations. We have two organizations,Org1.example.com and Org2.example.com ) network artifacts.

   5. Let’s generate the configuration transaction. The tool to generate the configuration transaction is called configtxgen. The artifacts generated in this step are the orderer genesis block, the channel configuration transaction, and one anchor peer transaction for each peer organization. There will also be a configtx.yaml file that is broken into several sections: profiles (describe the organizational structure of the network), organizations (the details regarding individual organizations), orderer (the details regarding the orderer parameters), and application (application defaults—not needed for this recipe).

   The profiles that are needed for this recipe are shown as follows:

   Profiles:

   TwoOrgsOrdererGenesis:

   <<: *ChannelDefaults

   Orderer:

   <<: *OrdererDefaults

   Organizations:

   *OrdererOrg

    

   Capabilities:

   <<: *OrdererCapabilities

   Consortiums:

   SampleConsortium:

   Organizations:

   *Org1

   *Org2

   TwoOrgsChannel:

   Consortium: SampleConsortium

   Application:
   <<: *ApplicationDefaults

   Organizations:

   *Org1

   *Org2

   Capabilities:

   <<: *ApplicationCapabilities

   Let’s go with the detailed command-line steps to understand what is happening:

   $ export FABRIC_CFG_PATH=$PWD

   sudo ../bin/configtxgen -profile TwoOrgsOrdererGenesis – outputBlock ./channel-artifacts/genesis.block

    export CHANNEL_NAME=mychannel

   sudo ../bin/configtxgen -profile TwoOrgsChannel

    

   -outputCreateChannelTx ./channel-artifacts/channel.tx -channelID $CHANNEL_NAME

   sudo ../bin/configtxgen -profile TwoOrgsChannel

    

   -outputAnchorPeersUpdate ./channel-artifacts/Org1MSPanchors.tx -channelID $CHANNEL_NAME -asOrg Org1MSP

   sudo ../bin/configtxgen -profile TwoOrgsChannel 

   -outputAnchorPeersUpdate ./channel-artifacts/Org2MSPanchors.tx -channelID $CHANNEL_NAME -asOrg Org2MSP

   Here, we write the blockchain genesis block, create the first channel transaction, and write anchor peer updates. You may not care how exactly it is done, but this is how Fabric is built from the bottom up. You can see that four new files are generated and stored in the channel-artifacts directory:

   • genesis.block
   • channel.tx
   • Org1MSPanchors.tx
   • Org2MSPanchors.tx

   6. The Docker Compose tool is used to bring up Docker containers. We use docker-compose-cli.yaml to keep track of all Docker containers that we bring up:

   $ cd ~

   $ cd fabric-samples/first-network

   $ sudo docker-compose -f docker-compose-cli.yaml up -d

   7. We have brought up six nodes: cli, orderer.example.com, peer0.org1.example.com, peer0.org2.example.com, peer1.org1.example.com, and peer1.org2.example.com:
   

   To recap, in this recipe, we learned the following:

   • Generating the crypto/certificate using cryptogen
   • Generating the configuration transaction using configtxgen
   • Bring up the nodes based on what is defined in the docker-compose file

   In our next recipe, we will work with Hyperledger Fabric CLI to set up network and manage chaincode. Specifically, we cover the following:

   • Using the CLI to set up the first network
   • Using the CLI to install and instantiate the chaincode
   • Using the CLI to invoke and query the chaincode

   It is good to know that after we set up our first network on Hyperledger Fabric, we move on to the following 3 steps or recipes:

   • Adding Organization to Channel in Hyperledger Fabric
   • Use CouchDB as a State Database for Hyperledger Fabric
   • Writing First Blockchain Application in Hyperledger Fabric

   This recipe is written in collaboration with Brian Wu who is a senior Hyperledger instructor at Coding Bootcamps school in Washington DC.

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