Multi Node

Following this page, you can run a localnet setup with docker that consists of a 4-node local chain. This setup can be useful for developers to test their applications and protocol features on a multi-node setup.

A similar setup is used by the LagomChain team to get insights about the impact of new features and testing different user flows. This testing setup can be found on the LagomChain testing repository.

Build & Start​

To build start a 4 node testnet using docker, run:

This command creates a 4-node network using the lagomdnode Docker image. The ports for each node are found in this table:

Node ID	P2P Port	Tendermint RPC Port	REST/ Ethereum JSON-RPC Port	WebSocket Port
lagomnode0	26656	26657	8545	8546
lagomnode1	26659	26660	8547	8548
lagomnode2	26661	26662	8549	8550
lagomnode3	26663	26664	8551	8552

To update the binary, just rebuild it and restart the nodes

The command above command will run containers in the background using Docker compose. You will see the network being created:

...
Creating network "lagom_localnet" with driver "bridge"
Creating lagomdnode0 ... done
Creating lagomdnode2 ... done
Creating lagomdnode1 ... done
Creating lagomdnode3 ... done

Stop Localnet​

Once you are done, execute:

Configuration​

The make localnet-start creates files for a 4-node testnet in ./build by calling the lagomd testnet command. This outputs a handful of files in the ./build directory:

tree -L 3 build/

build/
├── lagomd
├── lagomd
├── gentxs
│   ├── node0.json
│   ├── node1.json
│   ├── node2.json
│   └── node3.json
├── node0
│   ├── lagomd
│   │   ├── key_seed.json
│   │   └── keyring-test-cosmos
│   └── lagomd
│       ├── config
│       ├── data
│       └── lagomd.log
├── node1
│   ├── lagomd
│   │   ├── key_seed.json
│   │   └── keyring-test-cosmos
│   └── lagomd
│       ├── config
│       ├── data
│       └── lagomd.log
├── node2
│   ├── lagomd
│   │   ├── key_seed.json
│   │   └── keyring-test-cosmos
│   └── lagomd
│       ├── config
│       ├── data
│       └── lagomd.log
└── node3
├── lagomd
│   ├── key_seed.json
│   └── keyring-test-cosmos
└── lagomd
    ├── config
    ├── data
    └── lagomd.log

Each ./build/nodeN directory is mounted to the /lagomd directory in each container.

Logging​

In order to see the logs of a particular node you can use the following command:

# node 0: daemon logs
docker exec lagomdnode0 tail lagomd.log

# node 0: REST & RPC logs
docker exec lagomdnode0 tail lagomd.log

The logs for the daemon will look like:

I[2020-07-29|17:33:52.452] starting ABCI with Tendermint                module=main
E[2020-07-29|17:33:53.394] Can't add peer's address to addrbook         module=p2p err="Cannot add non-routable address [email protected]:26656"
E[2020-07-29|17:33:53.394] Can't add peer's address to addrbook         module=p2p err="Cannot add non-routable address [email protected]:26656"
E[2020-07-29|17:33:53.394] Can't add peer's address to addrbook         module=p2p err="Cannot add non-routable address [email protected]:26656"
I[2020-07-29|17:33:58.828] Executed block                               module=state height=88 validTxs=0 invalidTxs=0
I[2020-07-29|17:33:58.830] Committed state                              module=state height=88 txs=0 appHash=90CC5FA53CF8B5EC49653A14DA20888AD81C92FCF646F04D501453FD89FCC791
I[2020-07-29|17:34:04.032] Executed block                               module=state height=89 validTxs=0 invalidTxs=0
I[2020-07-29|17:34:04.034] Committed state                              module=state height=89 txs=0 appHash=0B54C4DB1A0DACB1EEDCD662B221C048C826D309FD2A2F31FF26BAE8D2D7D8D7
I[2020-07-29|17:34:09.381] Executed block                               module=state height=90 validTxs=0 invalidTxs=0
I[2020-07-29|17:34:09.383] Committed state                              module=state height=90 txs=0 appHash=75FD1EE834F0669D5E717C812F36B21D5F20B3CCBB45E8B8D415CB9C4513DE51
I[2020-07-29|17:34:14.700] Executed block                               module=state height=91 validTxs=0 invalidTxs=0

tip

You can disregard the Can't add peer's address to addrbook warning. As long as the blocks are being produced and the app hashes are the same for each node, there should not be any issues.

Whereas the logs for the REST & RPC server would look like:

I[2020-07-30|09:39:17.488] Starting application REST service (chain-id: "7305661614933169792")... module=rest-server
I[2020-07-30|09:39:17.488] Starting RPC HTTP server on 127.0.0.1:8545   module=rest-server
...

Follow Logs​

You can also watch logs as they are produced via Docker with the --follow (-f) flag, for example:

docker logs -f lagomdnode0

Interact with the Localnet​

Ethereum JSON-RPC & Websocket Ports​

To interact with the testnet via WebSockets or RPC/API, you will send your request to the corresponding ports:

EVM JSON-RPC	Eth Websocket
8545	8546

You can send a curl command such as:

curl -X POST --data '{"jsonrpc":"2.0","method":"eth_accounts","params":[],"id":1}' -H "Content-Type: application/json" 192.162.10.1:8545

tip

The IP address will be the public IP of the docker container.

Additional instructions on how to interact with the WebSocket can be found on the events documentation.

Keys & Accounts​

To interact with lagomd and start querying state or creating txs, you use the lagomd directory of any given node as your home, for example:

lagomd keys list --home ./build/node0/lagomd

Now that accounts exists, you may create new accounts and send those accounts funds!

tip

Note: Each node's seed is located at ./build/nodeN/lagomd/key_seed.json and can be restored to the CLI using the lagomd keys add --restore command

Special Binaries​

If you have multiple binaries with different names, you can specify which one to run with the BINARY environment variable. The path of the binary is relative to the attached volume. For example:

# Run with custom binary
BINARY=lagom make localnet-start