Casper NCTL - Docker Container

NCTL is a CLI application to control one or multiple Casper networks locally. Many developers wish to spin up relatively small test networks to localize their testing before deploying to the blockchain.

How to use this image

Start a network with five nodes

To create a container with the NCTL image write:

docker run --rm -it --name mynctl -d -p 11101:11101 -p 14101:14101 -p 18101:18101 makesoftware/casper-nctl

where mynctl is the name of the container. The ports for the first node in the network are published to the host.

Alternatively, you can use docker-compose to start and stop the container. Download the file docker-compose.yml in this repository and write:

docker-compose up

Activate nctl-* commands

To activate nctl-* commands in your local host, run the following command in a bash console:

source nctl-activate.sh mynctl

In a Powershell terminal, run:

. .\nctl-activate.ps1 mynctl

where mynctl is the name of the container.

Now you can write in the host machine commands like nctl-view-faucet-account, nctl-transfer-native, etc. For a complete list of commands, visit this page.

Sometimes you may need the secret key of the faucet, a node or one of the predefined users. After activating nctl-* commands you can execute the following commands:

nctl-view-faucet-secret-key

nctl-view-node-secret-key node=1

nctl-view-user-secret-key user=3

Run the container with predefined account keys

Each time the container is started, nctl runs with a set of randomly generated account keys. To use a set of predefined and pregenerated account keys, run the container with the environment variable PREDEFINED_ACCOUNTS set to true:

docker run --rm -it --name mynctl -d -p 11101:11101 --env PREDEFINED_ACCOUNTS=true makesoftware/casper-nctl

If you're using the docker-compose command, add the environment variable to the nctl service.

Change the settings using environment variables

Using environment variables you can tweak few parameters to change the frequency of blocks and the deploys processing speed.

Environment variable	Default value	Description
MINIMUM_ROUND_EXPONENT	12	Integer between 0 and 255 (0 included). The power of two that is the number of milliseconds in the minimum round length, and therefore the minimum delay between a block and its child. E.g. 12 means 2^12 milliseconds, i.e. about 4 seconds.
MAXIMUM_ROUND_EXPONENT	19	Integer between 0 and 255 (255 included). Must be greater than minimum_round_exponent. The power of two that is the number of milliseconds in the maximum round length, and therefore the maximum delay between a block and its child. E.g. 19 means 2^19 milliseconds, i.e. about 8.7 minutes.
DEPLOY_DELAY	1min	Deploys are only proposed in a new block if they have been received at least this long ago.

⚠️ Change these values carefully. Too low or too high minimum/maximum round exponent values will make the nodes malfunction.

You can also use your custom chainspec.toml and config.toml files:

Environment variable	Description
PATH_TO_CHAINSPEC	Absolute path to your custom chainspec.toml file. Usually you'll need to mount a volume connected to your host to make the file available in the container.
PATH_TO_CONFIG_TOML	Absolute path to your custom config.toml configuration file for the nodes.

Usually you'll need to mount a volume connected to your host to make the file available in the container.

Stop the container

To stop the container write:

docker stop mynctl

Or, if you're using docker-compose write:

docker-compose stop

Container shell access

The docker exec command allows you to run commands inside a Docker container. The following command line will give you a bash shell inside your nctl container:

docker exec -it mynctl bash

In the container shell you can use the casper-client tool as well as the nctl-* set of commands.

Use cors-anywhere to interact with the nodes from a browser

Browsers block direct RPC calls to Casper nodes due to CORS. If you're developing a web app you may use cors-anywhere to overcome this situation.

The cors folder in this repository contains a Docker Compose configuration to start a node.js server running cors-anywhere in addition to the NCTL container. To start both containers run the following command:

docker-compose --profile cors-anywhere up

Next, change your web app configuration to send the RPC calls to the node.js server indicating the casper node it has to redirect the traffic to:

http://127.0.0.1:11100/http://mynctl:11101/rpc

Use the Docker image in a GitHub action

An example of a GitHub Action running NCTL as a service container to execute integration tests.

name: CI

on:
  # Allows you to run this workflow manually from the Actions tab
  workflow_dispatch:

jobs:
  integration-test:
    # The type of runner that the job will run on
    runs-on: ubuntu-latest
    
    # Service containers to run with `runner-job`
    services:
      # Label used to access the service container
      casper-nctl:
        # Docker Hub image
        image: makesoftware/casper-nctl:latest
        options: --name casper-nctl
        env:
          PREDEFINED_ACCOUNTS: 'true'
          MINIMUM_ROUND_EXPONENT: '12'
          MAXIMUM_ROUND_EXPONENT: '14'
          DEPLOY_DELAY: '12sec'        
        ports:
          # Opens RPC, REST and events ports on the host and service container
          - 11101:11101
          - 14101:14101
          - 18101:18101
          
    steps:
      - uses: actions/checkout@v2
      - name: Setup .NET
        uses: actions/setup-dotnet@v1
        with:
          dotnet-version: 5.0.x
      - name: Obtain faucet secret key from container
        run: docker exec -t casper-nctl cat /home/casper/casper-node/utils/nctl/assets/net-1/faucet/secret_key.pem > Casper.Network.SDK.Test/TestData/faucetact.pem
      - name: Restore dependencies
        run: dotnet restore
      - name: Build
        run: dotnet build --no-restore
      - name: Test
        run: dotnet test --no-build --verbosity normal --settings Casper.Network.SDK.Test/test.runsettings --filter="TestCategory=NCTL" 

Build the Docker image from sources

To build the NCTL Docker image from the casper-node sources, follow the instructions in BUILD page.