Deploying Alpen smart contracts

In this walkthrough we will go through creating a very simple Counter contract, deploying it, and doing some simple contract calls.

Deploying a counter contract

This assumes that you have your local git configured.

1. Follow the official steps to install Foundry.

2. Initialize a project with init

forge init Counter
cd Counter

Forge will automatically add its standard counter at src/Counter.sol with the code below

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.13;

contract Counter {
    uint256 public number;

    function setNumber(uint256 newNumber) public {
        number = newNumber;
    }

    function increment() public {
        number++;
    }
}

1. Compile the contract

Test and build the Counter using Forge

forge test --evm-version "prague" ## runs the tests under Prague specs
forge build

1. Setup the environment

Before we deploy the contract, we need to make sure we can connect to the Alpen public RPC.

Add the following line to a new .env file in your Counter project folder:

ETH_RPC_URL=https://rpc.testnet.alpenlabs.io ## by declaring it as ETH_RPC_URL we don't need to add --rpc-url to all subsequent forge and cast commands

Run source .env to load these parameters in the active shell session and query the endpoint to verify we're on the correct network

curl -X POST $ETH_RPC_URL \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_chainId","params":[],"id":1}'

The expected result is 8150 in hex format: {"jsonrpc":"2.0","id":1,"result":"0x1fd6"}

You can also run a full node! See Alpen full node operator guide to host your own Alpen RPC endpoints.

1. Generate a deployer testnet wallet

From now on, you'll need a wallet with an active balance to deploy your contracts. Creating a dedicated deployer is a best practice to keep its private key separated from a standard user account.

Create a new mnemonic with

cast wallet new-mnemonic ## Backup or transcribe the Phrase and save the Address for later

You'll get an output similar to the following:

Generating mnemonic from provided entropy...
Successfully generated a new mnemonic.
Phrase:
pull pipe diagram aerobic horror child orange height blast true source tray

Accounts:
- Account 0:
Address:     0x2eAB7b2Cf9950621C05329Da3dE34c35B1c69108
Private key: 0x590fe557738fd3611527eb8303591aefd022a7842dc19f5209acd3cec493fee2

Backup or transcribe the 12-word Phrase, and save the Address for later.

Use import command with your mnemonic passphrase to add deployer to the Foundry keystore

cast wallet import deployer --mnemonic "pull pipe diagram ..." ## Copy/paste the 12-word passphrase you generated in the previous step inside the double quotes

Setup a wallet password (or keep it blank) to proceed. See the official Foundry cast documentation for more information on this step.

Foundry keeps all imported wallets in the common directory at ~/.foundry/keystores. If you already created and funded a deployer account, you can skip step 6.

1. Add balance to the deployer wallet

To get a few testnet coins, open the Alpen faucet at https://faucet.testnet.alpenlabs.io, click enter address, and copy/paste the deployer Address we saved before.

Alternatively, you can receive more coins by Using the Alpen CLI, but the time to bridge funds from Alpen signet is approximately 3 hours.

1. Deploy the contract

(Optional) Test the Counter using Alpen testnet RPC

forge test --fork-url $ETH_RPC_URL

Perform a dry run of the contract deployment with forge create

forge create Counter --account deployer ## the --account parameter instructs forge to take the private key from the keystore instead of adding it in clear-text

In the result, check that "chainId": "0x1fd6" is pointing at the right network. Issue the command echo $((0x1fd6)) to verify that the resulting chain ID number is 8150 :

Warning: Dry run enabled, not broadcasting transaction

Contract: Counter
Transaction: {
  "from": "0xef0a426c941722b9da46f6c54e78664a8ab154f8",
  "to": null,
  "maxFeePerGas": "0xf",
  "maxPriorityFeePerGas": "0x1",
  "gas": "0x26942",
  "input": "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",
  "nonce": "0x2",
  "chainId": "0x1fd6"
}
ABI: [
  {
    "type": "function",
    "name": "increment",
    "inputs": [],
    "outputs": [],
    "stateMutability": "nonpayable"
  },
  {
    "type": "function",
    "name": "number",
    "inputs": [],
    "outputs": [
      {
        "name": "",
        "type": "uint256",
        "internalType": "uint256"
      }
    ],
    "stateMutability": "view"
  },
  {
    "type": "function",
    "name": "setNumber",
    "inputs": [
      {
        "name": "newNumber",
        "type": "uint256",
        "internalType": "uint256"
      }
    ],
    "outputs": [],
    "stateMutability": "nonpayable"
  }
]

Warning: To broadcast this transaction, add --broadcast to the previous command. See forge create --help for more.

Finally, broadcast the transaction with the command

forge create Counter --account deployer --broadcast

1. Test the deployed contract

When the deployment is complete, Forge should return the following result. Note the Deployed to address, which will be our contract address

Deployer: 0xef0a426C941722B9da46F6C54E78664a8ab154F8
Deployed to: 0x0aF93a258c394d32483664d2EB90d4565087f2c2 ## This is our smart contract address
Transaction hash: 0x3d7df43291f46acec94ad60f0ad93ec86bb1f7f399f6d85d786a3598b4856b83

Append the contract address to the .env file to get a result similar to this one:

ETH_RPC_URL=https://rpc.testnet.alpenlabs.io
COUNTER_CONTRACT_ADDRESS="0x0aF93a25..." ## copy/paste the value from Deployed to inside double quotes to avoid parsing errors 

And issue the command source .env to have the smart contract address handy for the next steps.

Smoke-test the current state of our Counter with

cast call $COUNTER_CONTRACT_ADDRESS "number()(uint256)" ## It should return 0

Congratulations! We have now successfully deployed the Counter contract on Alpen Testnet.

Interacting with the Counter using cast

In this section, you will interact with the Counter contract using a separate account that we'll call user.

1. Create a user account and fund it with the faucet.

Follow the same steps used for the deployer

cast wallet nm ## Backup or transcribe the Phrase and save the Address for later

Generating mnemonic from provided entropy...
Successfully generated a new mnemonic.
Phrase:
urban shop knife please glide question canyon dust unusual initial lyrics taxi

Accounts:
- Account 0:
Address:     0xF4922E4C3193E58ADE54D2BC50A84F38C596E890
Private key: 0x4521e9dc4921233eb42d0a23b66a5d828b293d89f990f6b47bc93d1929cc77b6

And, similarly to the deployer, import the passphrase to the keystore:

cast wallet import user --mnemonic "urban shop knife ..." ## Copy/paste the 12-word passphrase inside the double quotes.

1. Fund the user account using the faucet

Open the Alpen testnet faucet at https://faucet.testnet.alpenlabs.io, click enter address, and copy/paste the user wallet address to receive a few testnet coins.

We can avoid the faucet entirely by sending coins from our deployer using Cast. First, make sure we have enough balance with the commands

cast wallet address --account deployer ## Returns the deployer wallet address
cast balance -e 0xef0a42... ## Copy/paste the deployer address to know its balance in sBTC

Then use the send command to transfer funds

cast wallet address --account user ## Returns the user wallet address
cast send 0xF4922E4C... --value 0.042ether --account deployer ## Sends 0.042 sBTC from deployer account to the user address generated above. 

Note that we use ether to instruct cast that it has to send the chain's native currency (on Alpen's testnet it is sBTC)

1. Interact with the Counter contract

First, view the current state of our Counter contract

cast call $COUNTER_CONTRACT_ADDRESS "number()(uint256)"

Then, increase it by one unit with the command

cast send $COUNTER_CONTRACT_ADDRESS "increment()" --account user

You should get a full execution report similar to the one below, with the line status 1(success) confirming that our contract call was successful

blockHash            0x50bc277f1257257fa1450c8a3f6b662fb9822c3fffb7d6cf3fe249f65a10171f
blockNumber          601598
contractAddress      
cumulativeGasUsed    26382
effectiveGasPrice    8
from                 0xd7a6B29B1d24389Ee2da9575fFbFB406f2B17c12
gasUsed              26382
logs                 []
logsBloom            0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
root                 
status               1 (success)
transactionHash      0xb4e6f08236da18dde29d02620818fea4e42c94c2e1f5276f86ed2b22c1236d3a
transactionIndex     0
type                 2
blobGasPrice         
blobGasUsed          
to                   0x0aF93a258c394d32483664d2EB90d4565087f2c2

Call again number() to see the new state of the Counter contract

cast call $COUNTER_CONTRACT_ADDRESS "number()(uint256)"

Optional: verify the contract on Alpen's Blockscout explorer

Alpen's Blockscout explorer supports forge verify-contract to publish a contract source code and show a Verified contract icon next to its address.

Issue the following command to send a verification request

forge verify-contract \
  --guess-constructor-args \
  --verifier blockscout \
  --verifier-url 'https://explorer.testnet.alpenlabs.io/api/' \
  --rpc-url 'https://explorer.testnet.alpenlabs.io/api/eth-rpc' \
  $COUNTER_CONTRACT_ADDRESS \
  src/Counter.sol:Counter \
  --watch

Right after it finished, open Alpen explorer at the verified contracts page to see our Counter listed at the top of the list.