Adding peer to a running network
Hello Folks,
Recently I discussed with you guys about various certification options in Blockchain and we saw in detail what is the pattern for Hyperledger fabric certification exam.
One such topic that is part of the problem-solving questions in Hyperledger fabric exam is adding a new peer to an existing network, this is something that is very commonly required in day to day implementation of a Hyperledger fabric network and that’s why holds a place in the certification exam but the this topic doesn’t hold a place in Hyperledger fabric product documentation so here we are going to talk about how can we add an peer to an Organization which is already part of a network and detail out the required steps
So, before we start, I have already done the groundwork and the sample BYFN network is up and running
You can do the same by following the Hyperledger fabric documentation.
Now we will start the process to add a peer to an existing network.
Step 1: Updating the crypto-config file, if you are aware about the steps to set up network “crypto-config” plays an important role and is the first step to start with so it’s the same for adding peer
The count property of crypto-config file defines the number of peers for any org defined in the file so adding a new peer to org first expects the count to be increased by the number of new peers needed
Here in the sample byfn network folder for crypto-config file we will increase the count from 2 to 3 since we want to add a new peer
Steps 2: Generate certificates for new peer, now since the new peer would belong to an existing org and we are extending the org with one more peer, we will run cryptogen tool again on the same crypto-config file but this time instead of generate we would use the extend flag for cryptogen tool
This command would simply update the existing crypto-config folder of certificates that had identity certificates initially only for two peers, and now will carry the newly created certificates of our new peer
Here you can see the new peer folder been added
Step 3: Setting up container for new Peer.
In this next step we need to update the docker-compose file of our network to include the new peer container configuration
For the ease of inputting new peer configuration, we would just refer the existing peer container configuration and replicate the same changing the peer name
docker-compose-cli.yaml
Next file is: docker-compose-base.yaml
While replicating the configuration keep in mind to update the port, volume, container name exactly and not to update the CORE_PEER_GOSSIP_BOOTSTRAP
Step 4: Now the further steps are very similar to starting the network
We are going to run the same command as to start the network and this time the docker composer will read the configuration file but this time the new peer’s configuration is read and since it doesn’t exist composer will create the container for new peer, using the configuration we added.
“docker-compose -f docker-compose-cli.yaml up -d”
Now we can see the new peer container running
Step 5: Next we’ll connect this new peer to the channel
Let’s enter the CLI container, here we would find the genesis block of our channel that we created earlier for other peers to join, we will use the same block
Set the environment variable pointing to new peer
CORE_PEER_MSPCONFIGPATH=/opt/gopath/src/github.com/hyperledger/fabric/peer/crypto/peerOrganizations/org1.example.com/users/Admin@org1.example.com/mspCORE_PEER_ADDRESS=peer2.org1.example.com:8151CORE_PEER_LOCALMSPID="Org1MSP"CORE_PEER_TLS_ROOTCERT_FILE=/opt/gopath/src/github.com/hyperledger/fabric/peer/crypto/peerOrganizations/org1.example.com/peers/peer2.org1.example.com/tls/ca.crt
And then connect the new peer to existing channel with below command
“peer channel join -b mychannel.block”
If we try to query the chaincode already running on the channel through this peer, this will fail since we don’t have the chaincode installed on this peer
Step 6: Now we would set chaincode on this peer and complete our tutorial
We would install chaincode with below command,
“peer chaincode install -n mycc -v 1.0 -p github.com/chaincode/chaincode_example02/go/”
Step7: In the end we will invoke the chaincode installed on our new peer, this would create a new chaincode container for our peer and would take some time to process for the first ever call
So that’s it, we have a new peer for org1 added to an existing running network.
