Single Node

This guide will help you set up a single node network on LagomChain. Running a single node is ideal for developers testing applications, smart contracts, and blockchain functionality due to its speed and simplicity.

For multi-node deployments, refer to the Multi-Node Setup Guide.

Prerequisite Readings​

• Install Binary

Automated Script​

The simplest way to start a local LagomChain node is by using the provided helper script on the base level of the LagomChain repository, which will create a sensible default configuration for testing purposes:

tip

To avoid overwriting any data for a real node used in production, it was decided to store the automatically generated testing configuration at ~/.tmp-lagomd instead of the default ~/.lagomd.

When working with the local_node.sh script, it is necessary to extend all lagomd commands, that target the local test node, with the --home ~/.tmp-lagomd flag. This is mandatory, because the home directory cannot be stored in the lagomd configuration, which can be seen in the output below. For ease of use, it might be sensible to export this directory path as an environment variable:

$ export TMP=$HOME/.tmp-lagomd`
$ lagomd config --home $TMP
{
"chain-id": "lagom_986-1",
"keyring-backend": "test",
"output": "text",
"node": "tcp://localhost:26657",
"broadcast-mode": "sync"
}

You can customize the local node script by changing the configuration variables. See the following excerpt from the script for ideas on what can be adjusted:

# Customize the name of your keys, the chain-id, moniker of the node, keyring backend, and more
KEYS[0]="dev0"
KEYS[1]="dev1"
KEYS[2]="dev2"
CHAINID="lagom_986-1
MONIKER="localtestnet"
# Remember to change to other types of keyring like 'file' in-case exposing to outside world,
# otherwise your balance will be wiped quickly
# The keyring test does not require private key to steal tokens from you
KEYRING="test"
KEYALGO="eth_secp256k1"
LOGLEVEL="info"
# Set dedicated home directory for the lagomd instance
HOMEDIR="$HOME/.tmp-lagomd"
# to trace evm
#TRACE="--trace"
TRACE=""

[...]

  # Adjust this set a different maximum gas limit
  jq '.consensus_params["block"]["max_gas"]="10000000"' "$GENESIS" >"$TMP_GENESIS" && mv "$TMP_GENESIS" "$GENESIS"

[...]

Manual Deployment​

This guide helps you create a single validator node that runs a network locally for testing and other development related uses.

Initialize the chain​

Before actually running the node, we need to initialize the chain, and most importantly its genesis file. This is done with the init subcommand:

$MONIKER=testing
$KEY=dev0
$CHAINID="lagom_986-1"

# The argument $MONIKER is the custom username of your node, it should be human-readable.
lagomd init $MONIKER --chain-id=$CHAINID

tip

You can edit this moniker later by updating the config.toml file.

The command above creates all the configuration files needed for your node and validator to run, as well as a default genesis file, which defines the initial state of the network. All these configuration files are in ~/.lagomd by default, but you can overwrite the location of this folder by passing the --home flag.

Genesis Procedure​

Adding Genesis Accounts​

Before starting the chain, you need to populate the state with at least one account using the keyring:

lagomd keys add my_validator

Once you have created a local account, go ahead and grant it some alagom tokens in your chain's genesis file. Doing so will also make sure your chain is aware of this account's existence:

lagomd add-genesis-account my_validator 10000000000alagom

Now that your account has some tokens, you need to add a validator to your chain.

For this guide, you will add your local node (created via the init command above) as a validator of your chain. Validators can be declared before a chain is first started via a special transaction included in the genesis file called a gentx:

# Create a gentx
# NOTE: this command lets you set the number of coins.
# Make sure this account has some coins with the genesis.app_state.staking.params.bond_denom denom
lagomd add-genesis-account my_validator 1000000000stake,10000000000alagom

A gentx does three things:

1. Registers the validator account you created as a validator operator account (i.e. the account that controls the validator).

2. Self-delegates the provided amount of staking tokens.

3. Link the operator account with a Tendermint node pubkey that will be used for signing blocks. If no --pubkey flag is provided, it defaults to the local node pubkey created via the lagomd init command above.

For more information on gentx, use the following command:

Collecting gentx​

By default, the genesis file do not contain any gentxs. A gentx is a transaction that bonds staking token present in the genesis file under accounts to a validator, essentially creating a validator at genesis. The chain will start as soon as more than 2/3rds of the validators (weighted by voting power) that are the recipient of a valid gentx come online after genesis_time.

A gentx can be added manually to the genesis file, or via the following command:

# Add the gentx to the genesis file
lagomd collect-gentxs

This command will add all the gentxs stored in ~/.lagomd/config/gentx to the genesis file.

Run Single Node​

Finally, check the correctness of the genesis.json file:

Now that everything is set up, you can finally start your node:

tip

To check all the available customizable options when running the node, use the --help flag.

You should see blocks come in.

The previous command allow you to run a single node. This is enough for the next section on interacting with this node, but you may wish to run multiple nodes at the same time, and see how consensus happens between them.

You can then stop the node using Ctrl+C.

Further Configuration​

Key Management​

To use the same key every time, replace:

lagomd keys add $KEY

With:

shCopyEditecho "your mnemonic here" | lagomd keys add $KEY --recover

LagomChain only supports 24-word mnemonics.

Export a Private Key for MetaMask

lagomd keys unsafe-export-eth-key $KEY

For more key management options:

lagomd keys --help

Keyring backend options​

The instructions above include commands to use test as the keyring-backend. This is an unsecured keyring that doesn't require entering a password and should not be used in production. Otherwise, LagomChain supports using a file or OS keyring backend for key storage. To create and use a file stored key instead of defaulting to the OS keyring, add the flag --keyring-backend file to any relevant command and the password prompt will occur through the command line. This can also be saved as a CLI config option with:

lagomd config keyring-backend file

tip

For more information about the Keyring and its backend options, click here.

Enable Tracing​

To enable tracing when running the node, modify the last line of the local_node.sh script to be the following command, where:

• $TRACER is the EVM tracer type to collect execution traces from the EVM transaction execution (eg. json|struct|access_list|markdown)

• $TRACESTORE is the output file which contains KVStore tracing (eg. store.txt)

lagomd start --evm.tracer $TRACER --tracestore $TRACESTORE --pruning=nothing $TRACE --log_level $LOGLEVEL --minimum-gas-prices=0.0001alagom --json-rpc.api eth,txpool,personal,net,debug,web3

Clearing data from chain​

Reset Data​

Alternatively, you can reset the blockchain database, remove the node's address book files, and reset the priv_validator.json to the genesis state.

danger

If you are running a validator node, always be careful when doing lagomd unsafe-reset-all. You should never use this command if you are not switching chain-id.

danger

IMPORTANT: Make sure that every node has a unique priv_validator.json. Do not copy the priv_validator.json from an old node to multiple new nodes. Running two nodes with the same priv_validator.json will cause you to double sign!

First, remove the outdated files and reset the data.

rm $HOME/.lagomd/config/addrbook.json $HOME/.lagomd/config/genesis.json
lagomd tendermint unsafe-reset-all --home $HOME/.lagomd

Your node is now in a pristine state while keeping the original priv_validator.json and config.toml. If you had any sentry nodes or full nodes setup before, your node will still try to connect to them, but may fail if they haven't also been upgraded.

Delete Data​

Data for the lagomd binary should be stored at ~/.lagomd, respectively by default. To delete the existing binaries and configuration, run:

To clear all data except key storage (if keyring backend chosen) and then you can rerun the full node installation commands from above to start the node again.

Recording Transactions Per Second (TPS)​

In order to get a progressive value of the transactions per second, we use Prometheus to return the values. The Prometheus exporter runs at address http://localhost:8877 so please add this section to your Prometheus installation config.yaml file like this

global:
scrape_interval: 10s

external_labels:
  monitor: 'lagom'

scrape_configs:
- job_name: 'lagom'

  scrape_interval: 10s

  static_configs:
    - targets: ['localhost:8877']

and then run Prometheus like this

prometheus --config.file=prom_config.yaml

and then visit the Prometheus dashboard at http://localhost:9090/ then navigate to the expression area and enter the following expression

rate(lagomd_transactions_processed[1m])

which will show the rate of transactions processed.