CCIP Starter Kit

Note

This repository represents an example of using a Chainlink product or service. It is provided to help you understand how to interact with Chainlink’s systems so that you can integrate them into your own. This template is provided "AS IS" without warranties of any kind, has not been audited, and may be missing key checks or error handling to make the usage of the product more clear. Take everything in this repository as an example and not something to be copy pasted into a production ready service.

This project demonstrates a couple of basic Chainlink CCIP use cases.

Prerequisites

• Git
• Current LTS Node.js version

Verify installation by typing:

node -v

and

npm -v

Getting Started

1. Install packages

npm install

2. Compile contracts

npm run compile

What is Chainlink CCIP?

Chainlink Cross-Chain Interoperability Protocol (CCIP) provides a single, simple, and elegant interface through which dApps and web3 entrepreneurs can securely meet all their cross-chain needs, including token transfers and arbitrary messaging.

With Chainlink CCIP, one can:

• Transfer supported tokens
• Send messages (any data)
• Send messages and tokens

CCIP receiver can be:

• Smart contract that implements CCIPReceiver.sol
• EOA

Note: If you send a message and token(s) to EOA, only tokens will arrive

To use this project, you can consider CCIP as a "black-box" component and be aware of the Router contract only. If you want to dive deep into it, check the Official Chainlink Documentation.

Usage

In the next section you can see a couple of basic Chainlink CCIP use case examples. But before that, you need to set up some environment variables.

We are going to use the @chainlink/env-enc package for extra security. It encrypts sensitive data instead of storing them as plain text in the .env file, by creating a new, .env.enc file. Although it's not recommended to push this file online, if that accidentally happens your secrets will still be encrypted.

1. Set a password for encrypting and decrypting the environment variable file. You can change it later by typing the same command.

npx env-enc set-pw

2. Now set the following environment variables: PRIVATE_KEY, Source Blockchain RPC URL, Destination Blockchain RPC URL. You can see available options in the .env.example file or check out the latest supported networks in the docs:

ETHEREUM_SEPOLIA_RPC_URL=""
OPTIMISM_SEPOLIA_RPC_URL=""
ARBITRUM_SEPOLIA_RPC_URL=""
AVALANCHE_FUJI_RPC_URL=""
POLYGON_AMOY_RPC_URL=""
BNB_CHAIN_TESTNET_RPC_URL=""
BASE_SEPOLIA_RPC_URL=""
KROMA_SEPOLIA_RPC_URL=""
WEMIX_TESTNET_RPC_URL=""
GNOSIS_CHIADO_RPC_URL=""
CELO_ALFAJORES_RPC_URL=""
METIS_SEPOLIA_RPC_URL=""
ZKSYNC_SEPOLIA_RPC_URL=""
SCROLL_SEPOLIA_RPC_URL=""

To set these variables, type the following command and follow the instructions in the terminal:

npx env-enc set

After you are done, the .env.enc file will be automatically generated.

If you want to validate your inputs you can always run the next command:

npx env-enc view

Test

There are two types of tests in this project:

• ./test/no-fork/: These tests run on your local hardhat node and do not require forking.
• ./test/fork/: These tests run on a forked mainnet network and require forking the source and destination blockchains.

No Fork

To run the tests that do not require forking, type:

npm run test:no-fork

Fork

The tests are forking Arbitrum Sepolia as source chain and Ethereum Sepolia as destination chain. Before you begin, make sure to set up the rpc urls in your .env.enc file.

To run the tests that require forking, type:

npm run test:fork

Faucet

You will need test tokens for some of the examples in this Starter Kit. Public faucets sometimes limit how many tokens a user can create and token pools might not have enough liquidity. To resolve these issues, CCIP supports two ERC20 tokens (CCIP-BnM and CCIP-LnM) that you can mint permissionlessly on each supported testnet so you don't run out of tokens while testing different scenarios. You can get the addresses for the test tokens, for each supported network, here. You can understand the architecture principles behind these two test tokens here.

To get 10**18 units of each of these tokens, use the faucet task. Keep in mind that the CCIP-BnM test token you can mint on all testnets, while CCIP-LnM you can mint only on Ethereum Sepolia. On other testnets, the CCIP-LnM token representation is a wrapped/synthetic asset called clCCIP-LnM.

npx hardhat faucet
--receiver <RECEIVER_ADDRESS>
--ccip-bnm <CCIP_BnM_ADDRESS> # Optional
--ccip-lnm <CCIP_LnM_ADDRESS> # Optional

For example, to mint tokens on ethereumSepolia run:

npx hardhat faucet --network ethereumSepolia --receiver <RECEIVER_ADDRESS>

Example 1 - Transfer CCIP Test Tokens from EOA to EOA

To transfer tokens from one EOA on one blockchain to another EOA on another blockchain you can use the ccip-token-transfer command:

npx hardhat ccip-token-transfer
--source-blockchain <sourceBlockchain>
--destination-blockchain <destinationBlockchain>
--receiver <receiverAddressOnDestinationBlockchain>
--token-address <tokenToSendAddressOnSourceBlockchain>
--amount <amountToSend>     # in units (eg wei)
--fee-token-address  <feeTokenAddress> # Optional
--router <sourceChainRouterAddress> # Optional
--gasLimit <gasLimit> # Optional

Where the list of supported chains consists of (case sensitive):

• ethereumSepolia
• polygonAmoy
• optimismSepolia
• arbitrumSepolia
• avalancheFuji
• bnbChainTestnet
• baseSepolia
• kromaSepolia
• wemixTestnet
• gnosisChiado
• celoAlfajores
• metisSepolia
• zksyncSepolia
• scrollSepolia

For example, if you want to send 100 units of CCIP-BnM token from Avalanche Fuji to Ethereum Sepolia, and you want to pay for CCIP fees in native coin (Avalanche Fuji AVAX in this case), run:

npx hardhat ccip-token-transfer --source-blockchain avalancheFuji --destination-blockchain ethereumSepolia --receiver <RECEIVER_ADDRESS> --token-address 0xD21341536c5cF5EB1bcb58f6723cE26e8D8E90e4 --amount 100 --gas-limit 0

If you want to pay for CCIP fees in Avalanche Fuji test LINK, expand the previous command with the additional --fee-token-address flag:

npx hardhat ccip-token-transfer --source-blockchain avalancheFuji --destination-blockchain ethereumSepolia --receiver <RECEIVER_ADDRESS> --token-address 0xD21341536c5cF5EB1bcb58f6723cE26e8D8E90e4 --amount 100 --gas-limit 0 --fee-token-address 0x0b9d5D9136855f6FEc3c0993feE6E9CE8a297846

The proposed CCIP best practice is to always verify the Router.sol address. If you want to pass the source blockchain Router.sol address you can use the optional --router flag:

npx hardhat ccip-token-transfer --source-blockchain avalancheFuji --destination-blockchain ethereumSepolia --receiver <RECEIVER_ADDRESS> --token-address 0xD21341536c5cF5EB1bcb58f6723cE26e8D8E90e4 --amount 100 --gas-limit 0 --fee-token-address 0x0b9d5D9136855f6FEc3c0993feE6E9CE8a297846 --router <ROUTER_ADDRESS>

⚠️ Note: The gas limit is set to 0 because the transaction is directed to an Externally Owned Account (EOA). Gas limits on destination chains are needed only when sending data or tokens to a smart contract.

Example 2 - Transfer Tokens from EOA to Smart Contract

To transfer tokens from EOA from the source blockchain to the smart contract on the destination blockchain, follow the next steps:

1. Deploy BasicMessageReceiver.sol to the destination blockchain, using the deploy-basic-message-receiver task:

npx hardhat deploy-basic-message-receiver
--router <routerAddress> # Optional

For example, if you want to send tokens from Avalanche Fuji to Ethereum Sepolia, you need to deploy this contract on Ethereum Sepolia, by running:

npx hardhat deploy-basic-message-receiver --network ethereumSepolia

Optionally, you can pass the address of the Chainlink CCIP Router.sol smart contract on the Ethereum Sepolia blockchain as a constructor argument. To do so, run the following command:

npx hardhat deploy-basic-message-receiver --network ethereumSepolia --router <ROUTER_ADDRESS>

2. Transfer tokens to the deployed smart contract using the ccip-token-transfer task, by putting its address as a receiver flag. For example, if you want to send 100 units of CCIP-BnM from Avalanche Fuji run:

npx hardhat ccip-token-transfer --source-blockchain avalancheFuji --destination-blockchain ethereumSepolia --receiver <BASIC_MESSAGE_RECEIVER_ADDRESS> --token-address 0xD21341536c5cF5EB1bcb58f6723cE26e8D8E90e4 --amount 100 --fee-token-address 0x0b9d5D9136855f6FEc3c0993feE6E9CE8a297846

3. Once the CCIP message is finalized on the destination blockchain, you can always withdraw received tokens from the BasicMessageReceiver.sol smart contract using the withdraw task. Note that the --token-address flag is optional. If not provided, native coins will be withdrawn.

npx hardhat withdraw
--beneficiary <withdrawTo>
--blockchain <basicMessageReceiverBlockchain>
--from <basicMessageReceiverAddress>
--token-address <tokenToWithdraw> # Optional, if left empty native coins will be withdrawn

For example, to withdraw 100 units of CCIP-BnM previously sent, run:

npx hardhat withdraw --beneficiary <BENEFICIARY_ADDRESS> --blockchain ethereumSepolia --from <BASIC_MESSAGE_RECEIVER_ADDRESS> --token-address 0xFd57b4ddBf88a4e07fF4e34C487b99af2Fe82a05

Example 3 - Transfer Token(s) from Smart Contract to any destination

To transfer a token or batch of tokens from a single, universal, smart contract to any address on the destination blockchain follow the next steps:

1. Deploy BasicTokenSender.sol to the source blockchain, using the deploy-basic-token-sender task:

npx hardhat deploy-basic-token-sender
--router <routerAddress> # Optional
--link <linkTokenAddress> # Optional

For example, if you want to send tokens from avalancheFuji to ethereumSepolia, run:

npx hardhat deploy-basic-token-sender --network avalancheFuji

2. [OPTIONAL] If you want to send tokens to the smart contract, instead of EOA, you will need to deploy BasicMessageReceiver.sol to the destination blockchain, using the deploy-basic-message-receiver task, and then put the address of that smart contract as a receiver.

For example, if you want to send tokens from the BasicTokenSender.sol smart contract on the Avalanche Fuji blockchain to the BasicMessageReceiver.sol smart contract on the Ethereum Sepolia blockchain, run:

npx hardhat deploy-basic-message-receiver --network ethereumSepolia

3. Fill the BasicTokenSender.sol with tokens/coins for fees (you can always withdraw it later). You can do it manually from your wallet or by running the following task:

npx hardhat fill-sender
--sender-address <addressOfBasicTokenSenderContractWeDeployed>
--blockchain <blockchain>
--amount <amountToSend>
--pay-fees-in <Native | LINK>

For example, if you want to send tokens from Avalanche Fuji and fund it with 3 Avalanche Fuji LINK for Chainlink CCIP fees, run:

npx hardhat fill-sender --sender-address <BASIC_TOKEN_SENDER_ADDRESS> --blockchain avalancheFuji --amount 3000000000000000000 --pay-fees-in LINK

4. Finally, send tokens by providing the array of {token, amount} objects, using the ccip-token-transfer-batch task:

npx hardhat ccip-token-transfer-batch
--source-blockchain <sourceBlockchain>
--basic-token-sender-address <addressOfBasicTokenSenderContractWeDeployed>
--destination-blockchain <destinationBlockchain>
--receiver <receiverAddressOnDestinationBlockchain>
--token-amounts <tokenAmounts>
--pay-fees-in <Native | LINK>
--router <router> # Optional

The payFeesIn flag determines whether you are paying for CCIP fees with LINK tokens or native coins on the source blockchain (Pass "Native" or "LINK").

For example, to send 100 units of CCIP-BnM tokens from avalancheFuji to ethereumSepolia and pay fees in Avalanche Fuji LINK, run:

npx hardhat ccip-token-transfer-batch --source-blockchain avalancheFuji --basic-token-sender-address <BASIC_TOKEN_SENDER_ADDRESS> --destination-blockchain ethereumSepolia --receiver <RECEIVER_ADDRESS> --token-amounts '[{"token":"0xD21341536c5cF5EB1bcb58f6723cE26e8D8E90e4","amount":"100"}]' --pay-fees-in LINK

5. You can always withdraw tokens for Chainlink CCIP fees from the BasicTokenSender.sol smart contract using the withdraw task. Note that the --token-address flag is optional. If not provided, native coins will be withdrawn.

npx hardhat withdraw
--beneficiary <withdrawTo>
--blockchain <basicTokenSenderBlockchain>
--from <basicTokenSenderAddress>
--token-address <tokensToWithdraw> # Optional, if left empty native coins will be withdrawn

For example, to withdraw the Avalanche Fuji LINK you previously sent for Chainlink CCIP fees, run:

npx hardhat withdraw --beneficiary <BENEFICIARY_ADDRESS> --blockchain avalancheFuji --from <BASIC_TOKEN_SENDER_ADDRESS> --token-address 0x0b9d5D9136855f6FEc3c0993feE6E9CE8a297846

Example 4 - Send & Receive Tokens and Data

To transfer tokens and data across multiple chains, follow the next steps:

1. Deploy the ProgrammableTokenTransfers.sol smart contract to the source blockchain, using the deploy-programmable-token-transfers task:

npx hardhat deploy-programmable-token-transfers
--router <router> # Optional

For example, if you want to send a message from Ethereum Sepolia to Polygon Amoy type:

npx hardhat deploy-programmable-token-transfers --network ethereumSepolia

2. Open Metamask and fund your contract with Native tokens. For example, if you want to send a message from Ethereum Sepolia to Polygon Amoy, you can send 0.1 Sepolia ETH to your contract.

3. Open Metamask and fund your contract with Sepolia CCIP-BnM tokens. For example, if you want to send a message from Ethereum Sepolia to Polygon Amoy, you can send 0.0000000000000001 Sepolia CCIP-BnM to your contract.

4. Deploy the ProgrammableTokenTransfers.sol smart contract to the destination blockchain:

For example, if you want to receive a message from Ethereum Sepolia on Polygon Amoy type:

npx hardhat deploy-programmable-token-transfers --network polygonAmoy

At this point, you have one sender contract on the source blockchain, and one receiver contract on the destination blockchain. Please note that ProgrammableTokenTransfers.sol can both send & receive tokens and data, hence we have two identical instances on both source and destination blockchains.

5. Send a message, by running:

npx hardhat send-token-and-data
--source-blockchain <sourceBlockchain>
--sender <addressOfProgrammableTokenTransfersOnSourceBlockchain>
--destination-blockchain <destinationBlockchain>
--receiver <ddressOfProgrammableTokenTransfersOnDestinationBlockchain>
--message <messageToSend>
--token-address <tokenToSendAddressOnSourceBlockchain>
--amount <amountToSend>
--router <router> # Optional

For example, if you want to send a "Hello World" message alongside 100 Sepolia CCIP-BnM from Ethereum Sepolia to Polygon Amoy type:

npx hardhat send-token-and-data --source-blockchain ethereumSepolia --sender <CONTRACT_ADDRESS_ON_SOURCE_BLOCKCHAIN> --destination-blockchain polygonAmoy --receiver <CONTRACT_ADDRESS_ON_DESTINATION_BLOCKCHAIN> --message "Hello World" --token-address 0xFd57b4ddBf88a4e07fF4e34C487b99af2Fe82a05 --amount 100

6. Once the CCIP message is finalized on the destination blockchain, you can see the details of the latest CCIP message received, by running the get-received-message-details task:

npx hardhat get-received-message-details
--blockchain <destinationBlockchain>
--contract-address <programmableTokenTransfersAddressOnDestinationBlockchain>

For example,

npx hardhat get-received-message-details --blockchain polygonAmoy --contract-address <PROGRAMMABLE_TOKEN_TRANSFERS_ADDRESS_ON_DESTINATION_BLOCKCHAIN>

Example 5 - Send & Receive Cross-Chain Messages and Pay with Native Coins

To send simple Text Cross-Chain Messages and pay for CCIP fees in Native Tokens, follow the next steps:

1. Deploy the BasicMessageSender.sol smart contract on the source blockchain, using the deploy-basic-message-sender task:

npx hardhat deploy-basic-message-sender
--router <routerAddress> # Optional
--link <linkTokenAddress> # Optional

For example, if you want to send a simple cross-chain message from Ethereum Sepolia, run

npx hardhat deploy-basic-message-sender --network ethereumSepolia

2. Fund the BasicMessageSender.sol smart contract with Native Coins, either manually using your wallet or by using the fill-sender task.

For example, if you want to send 0.01 Sepolia ether, run:

npx hardhat fill-sender --sender-address <BASIC_MESSAGE_SENDER_ADDRESS> --blockchain ethereumSepolia --amount 10000000000000000 --pay-fees-in Native

3. Deploy the BasicMessageReceiver.sol smart contract to the destination blockchain, using the deploy-basic-message-receiver task.

For example, if you want to receive a simple cross-chain message on the Avalanche Fuji blockchain, run:

npx hardhat deploy-basic-message-receiver --network avalancheFuji

4. Finally, send a cross-chain message using the send-message task:

npx hardhat send-message
--source-blockchain <sourceBlockchain>
--sender <addressOfBasicMessageSenderOnSourceBlockchain>
--destination-blockchain <destinationBlockchain>
--receiver <addressOfBasicMessageReceiverOnDestinationBlockchain>
--message <messageToSend>
--pay-fees-in <Native>

For example, if you want to send a "Hello, World!" message type:

npx hardhat send-message --source-blockchain ethereumSepolia --sender <BASIC_MESSAGE_SENDER_ADDRESS> --destination-blockchain avalancheFuji --receiver <BASIC_MESSAGE_RECEIVER_ADDRESS> --message 'Hello, World!' --pay-fees-in Native

5. Once the CCIP message is finalized on the destination blockchain, you can query the latest received message details, using the get-message task:

npx hardhat get-message
--blockchain <destinationBlockchain>
--receiver-address <basicMessageReceiverAddress>

For example, to get the message details sent in the previous step, type:

npx hardhat get-message --blockchain avalancheFuji --receiver-address <BASIC_MESSAGE_RECEIVER_ADDRESS>

6. You can always withdraw tokens for Chainlink CCIP fees from the BasicMessageSender.sol smart contract using the withdraw task. Note that the --token-address flag is optional. If not provided, native coins will be withdrawn.

npx hardhat withdraw
--beneficiary <withdrawTo>
--blockchain <basicMessageSenderBlockchain>
--from <basicMessageSenderAddress>
--token-address <tokensToWithdraw> # Optional, if left empty native coins will be withdrawn

For example, to withdraw Sepolia ether previously sent for Chainlink CCIP fees, run:

npx hardhat withdraw --beneficiary <BENEFICIARY_ADDRESS> --blockchain ethereumSepolia --from <BASIC_MESSAGE_SENDER_ADDRESS>

Example 6 - Send & Receive Cross-Chain Messages and Pay with LINK Tokens

To send simple Text Cross-Chain Messages and pay for CCIP fees in LINK Tokens, follow the next steps:

1. Deploy the BasicMessageSender.sol smart contract on the source blockchain, using the deploy-basic-message-sender task:

npx hardhat deploy-basic-message-sender
--router <routerAddress> # Optional
--link <linkTokenAddress> # Optional

For example, if you want to send a simple cross-chain message from Ethereum Sepolia, run

npx hardhat deploy-basic-message-sender --network ethereumSepolia

2. Fund the BasicMessageSender.sol smart contract with Testnet LINKs, either manually using your wallet or by using the fill-sender task.

For example, if you want to send 1 Sepolia LINK, run:

npx hardhat fill-sender --sender-address <BASIC_MESSAGE_SENDER_ADDRESS> --blockchain ethereumSepolia --amount 1000000000000000000 --pay-fees-in LINK

3. Deploy the BasicMessageReceiver.sol smart contract to the destination blockchain, using the deploy-basic-message-receiver task.

For example, if you want to receive a simple cross-chain message on the Avalanche Fuji blockchain, run:

npx hardhat deploy-basic-message-receiver --network avalancheFuji

4. Finally, send a cross-chain message using the send-message task:

npx hardhat send-message
--source-blockchain <sourceBlockchain>
--sender <addressOfBasicMessageSenderOnSourceBlockchain>
--destination-blockchain <destinationBlockchain>
--receiver <ddressOfBasicMessageReceiverOnDestinationBlockchain>
--message <messageToSend>
--pay-fees-in <LINK>

For example, if you want to send a "Hello, World!" message type:

npx hardhat send-message --source-blockchain ethereumSepolia --sender <BASIC_MESSAGE_SENDER_ADDRESS> --destination-blockchain avalancheFuji --receiver <BASIC_MESSAGE_RECEIVER_ADDRESS> --message 'Hello, World!' --pay-fees-in LINK

5. Once the CCIP message is finalized on the destination blockchain, you can query the latest received message details, using the get-message task:

npx hardhat get-message
--blockchain <destinationBlockchain>
--receiver-address <basicMessageReceiverAddress>

For example, to get the message details sent in the previous step, type:

npx hardhat get-message --blockchain avalancheFuji --receiver-address <BASIC_MESSAGE_RECEIVER_ADDRESS>

6. You can always withdraw tokens for Chainlink CCIP fees from the BasicMessageSender.sol smart contract using the withdraw task. Note that the --token-address flag is optional. If not provided, native coins will be withdrawn.

npx hardhat withdraw
--beneficiary <withdrawTo>
--blockchain <basicMessageSenderBlockchain>
--from <basicMessageSenderAddress>
--token-address <tokensToWithdraw> # Optional, if left empty native coins will be withdrawn

For example, to withdraw Sepolia LINK previously sent for Chainlink CCIP fees, run:

npx hardhat withdraw --beneficiary <BENEFICIARY_ADDRESS> --blockchain ethereumSepolia --from <BASIC_MESSAGE_SENDER_ADDRESS> --token-address 0x779877A7B0D9E8603169DdbD7836e478b4624789

Example 7 - Execute Received Message as a Function Call

Our goal for this example is to mint an NFT on the destination blockchain by sending the to address from the source blockchain. It is extremely simple so we can understand the basic concepts, but you can expand it to accept payment for minting on the source blockchain, grant minter role to CCIP receiver contract on the destination blockchain, etc.

The basic architecture diagram of what we want to accomplish looks like this:

flowchart LR
subgraph "Source Blockchain"
a("SourceMinter.sol") -- "`send abi.encodeWithSignature('mint(address)', msg.sender);`" --> b("Source Router")
end

b("Source Router") --> c("CCIP")

c("CCIP") --> d("Destination Router")

subgraph "Destination Blockchain"
d("Destination Router") -- "`receive abi.encodeWithSignature('mint(address)', msg.sender);`" --> e("DestinationMinter.sol")
e("DestinationMinter.sol") -- "`call mint(to)`" --> f("MyNFT.sol")
end

Loading

1. Deploy the MyNFT.sol and DestinationMinter.sol smart contracts from the ./contracts/cross-chain-nft-minter folder on the destination blockchain, by running the deploy-destination-cross-chain-nft-minter task:

npx hardhat deploy-destination-cross-chain-nft-minter
--router <routerAddress> # Optional

For example, if you want to mint NFTs on Ethereum Sepolia, run:

npx hardhat deploy-destination-cross-chain-nft-minter --network ethereumSepolia

2. Deploy the SourceMinter.sol smart contract on the source blockchain, by running the deploy-source-cross-chain-nft-minter task:

npx hardhat deploy-source-cross-chain-nft-minter
--router <routerAddress> # Optional
--link <linkTokenAddress> # Optional

For example, if you want to mint NFTs on avalancheFuji by sending requests from Avalanche Fuji, run:

npx hardhat deploy-source-cross-chain-nft-minter --network avalancheFuji

3. Fund the SourceMinter.sol smart contract with tokens for CCIP fees.

• If you want to pay for CCIP fees in Native tokens:

  Open Metamask and fund your contract with Native tokens. For example, if you want to mint from Avalanche Fuji to Ethereum Sepolia, you can send 1 AVAX to the SourceMinter.sol smart contract.

  Or, you can execute the fill-sender task, by running:

npx hardhat fill-sender
--sender-address <sourceMinterAddress>
--blockchain <blockchain>
--amount <amountToSend>
--pay-fees-in <Native>

For example, if you want to fund it with 1 Avalanche Fuji AVAX, run:

npx hardhat fill-sender --sender-address <SOURCE_MINTER_ADDRESS> --blockchain avalancheFuji --amount 1000000000000000000 --pay-fees-in Native

• If you want to pay for CCIP fees in LINK tokens:

  Open Metamask and fund your contract with LINK tokens. For example, if you want to mint from Avalanche Fuji to Ethereum Sepolia, you can send 1 Avalanche Fuji LINK to the SourceMinter.sol smart contract.

  Or, you can execute the fill-sender task, by running:

npx hardhat fill-sender
--sender-address <sourceMinterAddress>
--blockchain <blockchain>
--amount <amountToSend>
--pay-fees-in <LINK>

For example, if you want to fund it with 1 Avalanche Fuji LINK, run:

npx hardhat fill-sender --sender-address <SOURCE_MINTER_ADDRESS> --blockchain avalancheFuji --amount 1000000000000000000 --pay-fees-in LINK

4. Mint NFTs by calling the mint() function of the SourceMinter.sol smart contract on the source blockchain. It will send the CCIP Cross-Chain Message with the ABI-encoded mint function signature from the MyNFT.sol smart contract. The DestinationMinter.sol smart contracts will receive the CCIP Cross-Chain Message with the ABI-encoded mint function signature as a payload and call the MyNFT.sol smart contract using it. The MyNFT.sol smart contract will then mint the new NFT to the msg.sender account from the mint() function of the SourceMinter.sol smart contract, a.k.a to the account from which you will call the following command:

npx hardhat cross-chain-mint
--source-minter <sourceMinterAddress>
--source-blockchain <sourceBlockchain>
--destination-blockchain <destinationBlockchain>
--destination-minter <destinationMinterAddress>
--pay-fees-in <Native | LINK>

For example, if you want to mint NFTs on Ethereum Sepolia by sending requests from Avalanche Fuji and pay fees in LINK, run:

npx hardhat cross-chain-mint --source-minter <SOURCE_MINTER_ADDRESS> --source-blockchain avalancheFuji --destination-blockchain ethereumSepolia --destination-minter <DESTNATION_MINTER_ADDRESS> --pay-fees-in LINK

5. Once the CCIP message is finalized on the destination blockchain, you can query the MyNFTs balance of your account, using the cross-chain-mint-balance-of task:

npx hardhat cross-chain-mint-balance-of
--my-nft <myNftContractAddress>
--blockchain <destinationBlockchain>
--owner <theAccountToCheckBalanceOf>

For example, to verify that the new MyNFT was minted, type:

npx hardhat cross-chain-mint-balance-of --my-nft <MY_NFT_CONTRACT_ADDRESS> --blockchain ethereumSepolia --owner <PUT_YOUR_EOA_ADDRESS_HERE>

Of course, you can see your newly minted NFT on popular NFT Marketplaces, like OpenSea for instance:

6. You can always withdraw tokens for Chainlink CCIP fees from the SourceMinter.sol smart contract using the withdraw task. Note that the --token-address flag is optional. If not provided, native coins will be withdrawn.

npx hardhat withdraw
--beneficiary <withdrawTo>
--blockchain <sourceMinterBlockchain>
--from <sourceMinterAddress>
--token-address <tokensToWithdraw> # Optional, if left empty native coins will be withdrawn

For example, to withdraw tokens previously sent for Chainlink CCIP fees, run:

npx hardhat withdraw --beneficiary <BENEFICIARY_ADDRESS> --blockchain avalancheFuji --from <SOURCE_MINTER_ADDRESS>

or

npx hardhat withdraw --beneficiary <BENEFICIARY_ADDRESS> --blockchain avalancheFuji --from <SOURCE_MINTER_ADDRESS> --token-address 0x0b9d5D9136855f6FEc3c0993feE6E9CE8a297846

depending on whether you filled the SourceMinter.sol contract with Native or LINK in step number 3.