With the scale-down operation, you can remove the Replica and Client nodes from the existing VMware Blockchain topology when they are not needed.

The supported node configuration for scaling down is from n=10(f=3) to n=7(f=2) or n=4 (f=1). The Concord operator container must generate the new configuration for the selected nodes to scale down the number of nodes in a Replica Network. The new reconfiguration contains IP addresses, public keys, and certificates for the remaining Replica and Client nodes.

The scale down process is not successful under the following scenarios:

  • The TLS keys have changed

  • Replica node VMs have moved to a different VM



  1. SSH into the VMware Blockchain Orchestrator appliance.
  2. Enter the login credentials for the blockchain user account.
  3. Navigate to the /home/blockchain directory.
  4. Create a reconfigure scale down descriptor JSON file and set the parameter values in the descriptor directory.
  5. Validate your deployment descriptor file semantics against the deployment-descriptor-v1.schema.
  6. Validate that the credentials, network name, and folder name are correctly populated to avoid errors.
    docker-compose -f docker-compose-orchestrator.yml up
  7. Run the VMware Blockchain Orchestrator reconfigure script.
    docker-compose -f docker-compose-orchestrator.yml up

    The VMware Blockchain Orchestrator output file includes the session ID for the new node configuration.

  8. Stop all the applications that invoke the connection requests to the Daml Ledger in the original deployment.
  9. Stop the Client nodes.
    curl -X POST
  10. Identify the reconfiguration ID in the /home/blockchain/output directory.

    Reconfiguration Id: 626fdcfc-9c9c-4c25-b210-9e71c471e3cb

  11. Replace the old configuration ID with the reconfiguration ID in the /config/agent/config.json file.
  12. Instantiate the Concord operator container.

    You can only use one Client node, which is part of the original blockchain, as an Concord operator container.

    1. SSH into a Client node designated to host the operator Client node.

      Reboot the Concord container before using an operator container from a different Client node.

    2. Verify that the Client node has a Concord operator container image and identify the operator image ID.

      sudo docker images | grep "operator"

    3. Verify that the Concord operator container configuration file is available.
      sudo cat /config/daml-ledger-api/concord-operator/operator.config
    4. For deployments with unencrypted configuration, copy the private key content into the following location.
      sudo vi /config/daml-ledger-api/concord-operator/operator_priv.pem
    5. For deployments with encrypted configuration, deploy the encrypted operator private key content into the following location.

      The private key is encrypted and stored on disk because the deployment secure store configuration requires private keys not to be saved unprotected on disk.

      # Replace <OP_IMAGE_ID> and paste the operator private key when prompted
      sudo docker run -ti --network=blockchain-fabric --name=operator --entrypoint /operator/install_private_key.py --rm -v /config/daml-ledger-api/concord-operator:/operator/config-local -v /config/daml-ledger-api/concord-operator:/concord/config-public -v /config/clientservice/cert:/config/clientservice/cert -v /config/daml-ledger-api/config-public:/operator/config-public <Operator_IMAGE_ID>
    6. Launch the Concord operator container Client node.
      curl -X POST
    7. Access the Concord operator container Client node.
      sudo docker exec -it operator bash
  13. Log in to the scaled down blockchain configuration.

    The command stops the Replica nodes and downloads the new configuration on the Replica nodes.

    ./concop network-reconf addRemove-execute --configuration NEW_CONFIGURATION_ID \
                                              --auto \     #get the new configuration
                                              --restart \  #restart the replicas automatically
                                           #  --bft     \   # if you need n-f reconfiguration 
                                           #  --tokens   "{ \"node1_id\" : \"token\", \"node2_id\" : \"token\", ...}"
  14. Stop and shut down the Replica nodes removed from the blockchain topology.
    curl -X POST
    sudo docker stop agent
    sudo shutdown -h
  15. Shut down the agent on the Client nodes removed from the blockchain topology.
    sudo docker stop agent
    sudo shutdown -h
  16. Start the remaining Client nodes and agents.
    curl -X POST
    sudo docker restart agent
  17. Download the new configuration on the Client nodes.
    curl -ik -X POST http://localhost:8546/api/node/reconfigure/<new-config-ID>
  18. Start the Client node containers.
    curl -ik -X POST -H "content-type: application/json" --data '{ "containerNames" : ["all"] }' http://localhost:8546/api/node/restart

    If the containers do not start, use the start command curl -X POST