neo-go/docs/consensus.md

NeoGo consensus node

NeoGo node can act as a consensus node. A consensus node differs from a regular one in that it participates in block acceptance process using dBFT protocol. Any committee node can also be elected as a CN; therefore, they're expected to follow the same setup process as CNs (to be ready to become CNs if/when they're elected).

While regular nodes on Neo network don't need any special keys, CNs always have one used to sign dBFT messages and blocks. So, the main difference between a regular node and a consensus/committee node is that it should be configured to use some key from some wallet.

Running a CN on public networks

Hardware requirements

While NeoGo can be very conservative with its resource consumption, public network CN provides some service to the general audience and thus should have enough hardware resources to do its job reliably. We recommend amd64 machine with at least two cores, 8+ GB of memory and 64 GB SSD (disk space requirements depend on actual chain height and KeepOnlyLatestState/RemoveUntraceableBlocks settings, 64 GB is considered to be enough for the first year of blockchain).

OS requirements

NeoGo is a single binary that can be run on any modern GNU/Linux distribution. We recommend using major well-supported OSes like CentOS, Debian or Ubuntu. Make sure they're updated with the latest security patches.

No additional packages are needed for NeoGo CN.

Installation

Download NeoGo binary from Github or use Docker image. It has everything included, no additional plugins needed.

Take an appropriate (mainnet/testnet) configuration from the repository and save it in some directory (we'll assume that it's available in the same directory as neo-go binary).

Configuration and execution

Add the following subsection to ApplicationConfiguration section of your configuration file (protocol.mainnet.yml or protocol.testnet.yml):

  Consensus:
    Enabled: true
    UnlockWallet:
      Path: "wallet.json"
      Password: "welcometotherealworld"

where wallet.json is a path to your NEP-6 wallet and welcometotherealworld is a password to your CN key. Run the node in a regular way after that:

$ neo-go node --mainnet --config-path ./

where --mainnet is your network (can be --testnet for testnet) and --config-path is a path to the configuration file directory. If the node starts fine, it'll be logging events like synchronized blocks. The node doesn't have any interactive CLI, it only outputs logs so you can wrap this command in a systemd service file to run automatically on system startup.

Notice that the default configuration has RPC and Prometheus services enabled. You can turn them off for security purposes or restrict access to them with a firewall. Carefully review all other configuration options to see if they meet your expectations. Details on various configuration options are provided in the node configuration documentation, CLI commands are provided in the CLI documentation.

Consensus service can also run in watch-only mode when the node will receive/process/log dBFT messages generated by other nodes, but won't be able to generate any. It's mostly useful for debugging/monitoring. To enable this mode just drop the UnlockWallet section from the configuration like this:

  Consensus:
    Enabled: true

Registration

To register as a candidate, use neo-go as CLI command with an external RPC server for it to connect to (for chain data and transaction submission). You can use any public RPC server or an RPC server of your own like the node started at the previous step. We'll assume that you run the next command on the same node in default configuration with RPC interface available at port 10332.

Candidate registration is performed via NEO contract invocation that costs 1000 GAS, so your account must have enough of it to pay. You need to provide your wallet and address to neo-go command:

$ neo-go wallet candidate register -a NiKEkwz6i9q6gqfCizztDoHQh9r9BtdCNa -w wallet.json -r http://localhost:10332

where NiKEkwz6i9q6gqfCizztDoHQh9r9BtdCNa is your address, wallet.json is a path to NEP-6 wallet file and http://localhost:10332 is an RPC node to use.

This command will create and send appropriate transaction to the network and you should then wait for it to settle in a block. If all goes well, it'll end with "HALT" state and your registration will be completed. You can use query tx command to see transaction status or query candidates to see if your candidate has been added.

Voting

After registration is completed, if you own some NEO, you can also vote for your candidate to help it become a CN and receive additional voter GAS. To do that, you need to know the public key of your candidate, which can either be seen in query candidates command output or extracted from wallet wallet dump-keys command:

$ neo-go wallet dump-keys -w wallet.json
NiKEkwz6i9q6gqfCizztDoHQh9r9BtdCNa (simple signature contract):
0363f6678ea4c59e292175c67e2b75c9ba7bb73e47cd97cdf5abaf45de157133f5

0363f6678ea4c59e292175c67e2b75c9ba7bb73e47cd97cdf5abaf45de157133f5 is a public key for NiKEkwz6i9q6gqfCizztDoHQh9r9BtdCNa address. To vote for it use:

$ neo-go wallet candidate vote -a NiKEkwz6i9q6gqfCizztDoHQh9r9BtdCNa -w wallet.json -r http://localhost:10332 -c 0363f6678ea4c59e292175c67e2b75c9ba7bb73e47cd97cdf5abaf45de157133f5

where NiKEkwz6i9q6gqfCizztDoHQh9r9BtdCNa is the voter's address, wallet.json is the NEP-6 wallet file path, http://localhost:10332 is the RPC node address and 0363f6678ea4c59e292175c67e2b75c9ba7bb73e47cd97cdf5abaf45de157133f5 is the public key the voter votes for. This command also returns transaction hash and you need to wait for this transaction to be accepted into one of subsequent blocks.

Private NeoGo network

Using existing Dockerfile

neo-go comes with two preconfigured private network setups, the first one has four consensus nodes and the second one uses single node. Nodes are packed into Docker containers and four-node setup shares a volume for chain data.

Four-node setup uses ports 20333-20336 for P2P communication and ports 30333-30336 for RPC (Prometheus monitoring is also available at ports 20001-20004). Single-node is on ports 20333/30333/20001 for P2P/RPC/Prometheus.

NeoGo default privnet configuration is made to work with four-node consensus, you have to modify it if you're to use single consensus node.

Node wallets are located in the .docker/wallets directory where wallet1_solo.json is used for single-node setup and all others for four-node setup.

Prerequisites

• docker of version >= 20.10.0
• docker compose V2
• go compiler

Instructions

You can use an existing docker-compose file located in .docker/docker-compose.yml:

make env_image # build image
make env_up    # start containers, use "make env_single" for single CN

To monitor logs:

docker compose -f .docker/docker-compose.yml logs -f

To stop:

make env_down

To remove old blockchain state:

make env_clean

Start nodes manually

1. Create a separate config directory for every node and place the corresponding config named protocol.privnet.yml there.

2. Edit configuration file for every node. Examples can be found at config/protocol.privnet.docker.one.yml (two, three etc.).

   1. Add Consensus section with Enabled: true field and an UnlockWallet subsection with Path and Password strings for NEP-6 wallet path and the password for the account to be used for the consensus node.
   2. Make sure that your MinPeers setting is no more than the number of nodes participating in consensus minus one. The recommended setting is 2F in terms of BFT, that's the minimum number the network can operate with (0 for a single node, 2 for 4 CNs, 4 for 7 CNs).
   3. Set Address, Port and RPC.Port to the appropriate values. They must differ between nodes.
   4. If you start binary from the same directory, you will probably want to change DataDirectoryPath from the LevelDBOptions.

3. Start all nodes with neo-go node --config-path <dir-from-step-2>.