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Premining Balances

Overview​

In this tutorial, you will gain an understanding on how to premine native currency on a local gno.land chain. Additionally, you will understand how to query the account balance after you premine it.

Premining balance is the process of making sure some accounts (addresses) have specific funds when the chain initially launches. In the context of local chain deployments, premine balances are used to ensure the user accounts (developers) have ample funds to interact with the chain and facilitate contract deployments.

Prerequisites​

1. Clean chain data​

In order for us to premine funds on a fresh chain, we need to make sure we do not have any leftover blockchain data from previous chain runs.

The blockchain node, when it runs, works with an embedded DB locally on disk to store execution data (such as configuration files, or the state DB). For Gno blockchain nodes, this working directory is labeled as gnoland-data by default.

To clean out old blockchain data, navigate to the gno.land folder and run the appropriate make command:

cd gno.land
make fclean

2. Change the genesis_balances.txt file​

When the Gno node boots up, among other things, it reads a file called genesis_balances.txt to generate the initial balance set for the blockchain.

An example of how this looks like in the initial genesis.json file after the chain starts:

  "app_state": {
    "@type": "/gno.GenesisState",
    "balances": [
      "g1jg8mtutu9khhfwc4nxmuhcpftf0pajdhfvsqf5=10000000000000ugnot",
      "g1us8428u2a5satrlxzagqqa5m6vmuze025anjlj=10000000000000ugnot",
      "g1f4v282mwyhu29afke4vq5r2xzcm6z3ftnugcnv=1000000000000ugnot",
      "g127jydsh6cms3lrtdenydxsckh23a8d6emqcvfa=1000000000000ugnot"
    ],

The genesis_balances.txt file is located at ./gno.land/genesis/genesis_balances.txt. To add a new entry to the premine table, simply append a line to the end of the file:

g1qpymzwx4l4cy6cerdyajp9ksvjsf20rk5y9rtt=10000000000ugnot # My address

Replace g1qpymzwx4l4cy6cerdyajp9ksvjsf20rk5y9rtt with the address you want balance on, and 10000000000ugnot with the desired ugnot balance.

3. Start the local chain​

Now that our address and the desired premine balance are located in the genesis_balances.txt file, we can start the local Gno node. To run the local Gno node, make sure you are in the gno.land sub-folder, and run the appropriate make command:

cd gno.land
gnoland start

This command will initialize the Gno node, generate the genesis.json with our newly added premine information, and start the chain. gnoland start

3. Check the account balance​

To check the balance of any account (or the account we just premined), we can use the following ABCI query:

gnokey query --remote localhost:26657 bank/balances/g1qpymzwx4l4cy6cerdyajp9ksvjsf20rk5y9rtt

Let's break down this command:

  • --remote - the JSON-RPC URL of the running Gno node. In the case of a local deployment, the default value is localhost:26657
  • bank/balances/g1qpymzwx4l4cy6cerdyajp9ksvjsf20rk5y9rtt - the ABCI query targets the bank module to find the balances for address g1qpymzwx4l4cy6cerdyajp9ksvjsf20rk5y9rtt. Replace the address with your desired address gnokey query

Conclusion​

That's it 🎉 You have successfully premined a native currency balance on a locally-running Gno chain! Additionally, you have also learned how to query the native currency balance for an address, using built-in ABCI queries and the gnokey tool.