Create instructions

A new token

Now that our Client helper is ready, let's use it to build a new transaction. In this tutorial, we'll build a simple transaction that creates a new Solana token using the Token program.

More precisely, we will create a Mint account which is the main account that represents a Solana token. We will need at least two instructions to create a new Mint account:

• The CreateAccount instruction of the System program. This will allocate a new account on the Solana blockchain and assign it to the Token program.
• The InitializeMint instruction of the Token program. This will initialize the previously allocated account as a new Mint account.

The createMint helper

Before we start constructing these instructions, let's create a new create-mint.ts file under our src directory. We'll export a createMint function that will be responsible for building and sending the transaction that creates a new Mint account.

We'll accept our Client object as the first argument and some options as the second argument. To keep things simple, we'll only support customizing the number of decimals for the new Mint account.

import type { Client } from "./client";
 
export async function createMint(client: Client, options: { decimals?: number } = {}) {
  // ...
}

Next, let's start building our instructions inside that createMint helper.

The CreateAccount instruction

To allocate a new account on the Solana blockchain, we need to use the CreateAccount instruction of the System program. We can build this instruction using the getCreateAccountInstruction helper from the @solana-program/system library.

import { getCreateAccountInstruction } from "@solana-program/system";
 
import type { Client } from "./client";
 
export async function createMint(client: Client, options: { decimals?: number } = {}) {
  // Build instructions.
  const createAccountIx = getCreateAccountInstruction({
    payer,
    newAccount,
    space,
    lamports,
    programAddress,
  });
}

As you can see, the getCreateAccountInstruction helper requires a handful of inputs that we need to provide:

• The payer signer that will pay for the storage fees of the newly allocated account. In our case, we'll use the wallet signer of our Client object.

  const payer = client.wallet;

• The newAccount itself as a signer. Since this can be any address, we'll generate a new one and save it as a mint variable.

  import { generateKeyPairSigner } from "@solana/kit";
  const mint = await generateKeyPairSigner();

• The space we want to allocated for the new account. For this, we can use the getMintSize helper from the @solana-program/token library.

  import { getMintSize } from "@solana-program/token";
  const mintSize = getMintSize();

• The number of lamports to transfer to the new account in order to pay for the storage fees. This can be deduced from the size we want to allocate for the account by using getMinimumBalanceForRentExemption RPC method. This method returns the minimum lamports required for an account of the given size.

  const mintRent = await client.rpc.getMinimumBalanceForRentExemption(BigInt(mintSize)).send();

• The programAddress of the program that will own the new account. In our case, that's the Token program whose address is accessible via the TOKEN_PROGRAM_ADDRESS constant of the @solana-program/token library.

  import { TOKEN_PROGRAM_ADDRESS } from "@solana-program/token";
  const programAddress = TOKEN_PROGRAM_ADDRESS;

We end up with the following code. Notice how we wrapped a few promises that could be executed in parallel in a Promise.all to make the code more efficient.

import { generateKeyPairSigner } from "@solana/kit";
import { getCreateAccountInstruction } from "@solana-program/system";
import { getMintSize, TOKEN_PROGRAM_ADDRESS } from "@solana-program/token";
 
import type { Client } from "./client";
 
export async function createMint(client: Client, options: { decimals?: number } = {}) {
  // Prepare inputs.
  const mintSize = getMintSize();
  const [mint, mintRent] = await Promise.all([
    generateKeyPairSigner(),
    client.rpc.getMinimumBalanceForRentExemption(BigInt(mintSize)).send(),
  ]);
 
  // Build instructions.
  const createAccountIx = getCreateAccountInstruction({
    payer: client.wallet,
    newAccount: mint,
    space: mintSize,
    lamports: mintRent,
    programAddress: TOKEN_PROGRAM_ADDRESS,
  });
}

The InitializeMint instruction

Now that we have an empty account allocated on chain, let's initialize it as a Mint account. For that, we can use the getInitializeMintInstruction helper from the @solana-program/token library.

import { getInitializeMintInstruction } from "@solana-program/token";
 
const initializeMintIx = getInitializeMintInstruction({
  mint,
  decimals,
  mintAuthority,
  freezeAuthority,
});

This time, the instruction requires we provide the following inputs:

• The address of the mint account we just allocated. Since we already generated a new mint signer, we just need to provide mint.address.
• The number of decimals for the new Mint account. We'll use the options.decimals argument or default to 0.
• The authority that can mint new tokens. Here, we'll use the wallet signer of our Client object.
• The optional authority that can freeze tokens. Let's also use the wallet signer for this.

We end up with the following code:

import { generateKeyPairSigner } from "@solana/kit";
import { getCreateAccountInstruction } from "@solana-program/system";
import { getInitializeMintInstruction, getMintSize, TOKEN_PROGRAM_ADDRESS } from "@solana-program/token";
 
import type { Client } from "./client";
 
export async function createMint(client: Client, options: { decimals?: number } = {}) {
  // Prepare inputs.
  const mintSize = getMintSize();
  const [mint, mintRent] = await Promise.all([
    generateKeyPairSigner(),
    client.rpc.getMinimumBalanceForRentExemption(BigInt(mintSize)).send(),
  ]);
 
  // Build instructions.
  const createAccountIx = getCreateAccountInstruction({
    payer: client.wallet,
    newAccount: mint,
    space: mintSize,
    lamports: mintRent,
    programAddress: TOKEN_PROGRAM_ADDRESS,
  });
  const initializeMintIx = getInitializeMintInstruction({
    mint: mint.address,
    decimals: options.decimals ?? 0,
    mintAuthority: client.wallet.address,
    freezeAuthority: client.wallet.address,
  });
}

Compute budget instructions

On top of any instructions we might need in our transactions, we may also use instructions from the Compute Budget program to configure our transaction's compute allocation. For instance, we may use the SetComputeUnitLimit instruction to set the maximum number of compute units (CUs) that our transaction can consume. The lower that number is, the higher the chances that our transaction will be included in the next block. Additionally, the SetComputeUnitPrice instruction can be used to provide additional priority fees for our transactions in the form of micro-lamports per CU.

If we wanted to include these instructions explicitly in our transaction, we could use the getSetComputeUnitLimitInstruction and getSetComputeUnitPriceInstruction helpers from the @solana-program/compute-budget library.

import { getSetComputeUnitLimitInstruction, getSetComputeUnitPriceInstruction } from "@solana-program/compute-budget";
 
const setComputeLimitIx = getSetComputeUnitLimitInstruction({
  units: 50_000, // 50k CUs per transaction.
});
const setComputePriceIx = getSetComputeUnitPriceInstruction({
  microLamports: 10_000, // 10k micro-lamports per CU, as priority fees.
});

However, for this tutorial, we won't set up priority fees and we will use another helper to estimate the compute unit our transaction will consume by simulating it. We will tackle this — as well as the transaction message construction — in the next article.