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Setting up a Local Chain

Overview​

In this tutorial, you will learn how to start a local Gno node (and chain!). Additionally, you will see the different options you can use to make your Gno instance unique.

Prerequisites​

Starting a node with a default configuration​

You can start a Gno blockchain node with the default configuration by navigating to the gno.land sub-folder and running the following command:

gnoland start

The command will trigger a chain initialization process (if you haven't run the node before), and start the Gno node, which is ready to accept transactions and interact with other Gno nodes.

gnoland start

To view the command defaults, simply run the help command:

gnoland start --help

Let's break down the most important default settings:

  • chainid - the ID of the Gno chain. This is used for Gno clients, and distinguishing the chain from other Gno chains (ex. through IBC)
  • config - the custom node configuration file for more details on utilizing this file
  • genesis-balances-file - the initial premine balances file, which contains initial native currency allocations for the chain. By default, the genesis balances file is located in gno.land/genesis/genesis_balances.txt, this is also the reason why we need to navigate to the gno.land sub-folder to run the command with default settings
  • data-dir - the working directory for the node configuration and node data (state DB)
Resetting the chain

As mentioned, the working directory for the node is located in data-dir. To reset the chain, you need to delete this directory and start the node up again. If you are using the default node configuration, you can run make fclean from the gno.land sub-folder to delete the tempdir working directory.

Changing the chain ID​

Changing the Gno chain ID has several implications
  • It affects how the Gno node communicates with other Gno nodes / chains
  • Gno clients that communicate through JSON-RPC need to match this value

It's important to configure your node properly before launching it in a distributed network. Keep in mind that changes may not be applicable once connected.

To change the Gno chain ID, run the following command:

gnoland start --chainid NewChainID

We can verify the chain ID has been changed, by fetching the status of the node and seeing the associated chain ID. By default, the node exposes the JSON-RPC API on http://127.0.0.1:26657:

curl -H "Content-type: application/json" -d '{
    "jsonrpc": "2.0",
    "method": "status",
    "params": [],
    "id": 1
}' 'http://127.0.0.1:26657'

We should get a response similar to this:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "node_info": {
      "version_set": [
        // ...
      ],
      "net_address": "g10g9r37g9xa54a6clttzmhk2gmdkzsntzty0cvr@0.0.0.0:26656",
      "network": "NewChainID"
      // ...
    }
  }
}
Chain ID can be set only once

Since the chain ID information is something bound to a chain, you can only change it once upon chain initialization, and further attempts to change it will have no effect.

Changing the node configuration​

You can specify a node configuration file using the --config flag.

gnoland start --config config.toml

Changing the premine list​

You do not need to use the gno.land/genesis/genesis_balances.txt file as the source of truth for initial network funds.

To specify a custom balance sheet for a fresh local chain, you can use the -genesis-balances-file:

gnoland start -genesis-balances-file custom-balances.txt

Make sure the balances file follows the following format:

<address>=<balance>ugnot

Following this pattern, potential entries into the genesis balances file would look like:

g1qpymzwx4l4cy6cerdyajp9ksvjsf20rk5y9rtt=10000000000ugnot
g1u7y667z64x2h7vc6fmpcprgey4ck233jaww9zq=10000000000ugnot