Deploy a contract from installed Wasm bytecode using a deployer contract

Overview

This guide walks through the process of deploying a smart contract from installed Wasm bytecode using a deployer contract. We will cover setting up your environment, uploading Wasm bytecode, and deploying and initializing a contract atomically.

Prerequisites:

Basic understanding of Rust programming language. To brush up on Rust, check out Rustlings or The Rust book.
Familiarity with Stellar smart contracts
Installed Cargo, Stellar CLI and Soroban SDK

Setup environment

The deployer example demonstrates how to deploy contracts using a contract.

Clone the Soroban Examples Repository:

git clone -b main https://github.com/stellar/soroban-examples

Navigate to the Deployer Example:

cd soroban-examples/deployer/deployer

For this example to work, you should navigate to deployer/contract and deployer/deployer and run the command stellar contract build in each directory to generate the target files.

Run tests:

In the deployer/deployer, run the following command:

cargo test

You should see the output indicating the tests passed:

running 1 test
test test::test ... ok

Code overview

deployer/deployer/src/lib.rs

#[contract]
pub struct Deployer;

const ADMIN: Symbol = symbol_short!("admin");

#[contractimpl]
impl Deployer {
    /// Construct the deployer with a provided administrator.
    pub fn __constructor(env: Env, admin: Address) {
        env.storage().instance().set(&ADMIN, &admin);
    }

    /// Deploys the contract on behalf of the `Deployer` contract.
    ///
    /// This has to be authorized by the `Deployer`s administrator.
    pub fn deploy(
        env: Env,
        wasm_hash: BytesN<32>,
        salt: BytesN<32>,
        constructor_args: Vec<Val>,
    ) -> Address {
        let admin: Address = env.storage().instance().get(&ADMIN).unwrap();
        admin.require_auth();

        // Deploy the contract using the uploaded Wasm with given hash on behalf
        // of the current contract.
        // Note, that not deploying on behalf of the admin provides more
        // consistent address space for the deployer contracts - the admin could
        // change or it could be a completely separate contract with complex
        // authorization rules, but all the contracts will still be deployed
        // by the same `Deployer` contract address.
        let deployed_address = env
            .deployer()
            .with_address(env.current_contract_address(), salt)
            .deploy_contract(ContractExecutable::Wasm(wasm_hash), constructor_args);

        deployed_address
    }
}

How it works

The deployer contract provides a mechanism to deploy other contracts in a secure and deterministic manner. It stores an administrator address at construction time and requires that administrator’s authorization for every deployment. It also supports atomic initialization of the newly deployed contract via constructor arguments. This guarantees that the contract is properly initialized immediately after deployment, preventing any potential issues with uninitialized contracts.

Function breakdown

env: Env: The Env object represents the current contract execution environment. It provides methods to interact with the blockchain and other contracts, as well as perform various operations.
admin: Address: The Address of the administrator, provided to the __constructor function and stored for later use. Only this address can authorize deployments.
wasm_hash: BytesN<32>: The hash of the Wasm bytecode of the contract to be deployed and must already be installed and on the ledger. This hash is used to uniquely identify the contract’s code.
salt: BytesN<32>: A unique value used to derive the address of the deployed contract. The same combination of the Deployer contract’s address and salt will always produce the same deployed contract address, ensuring deterministic contract addresses.
constructor_args: Vec<Val>: A vector of arguments, specified as {type: value} objects, to be passed to the constructor of the deployed contract.

Function steps

let admin: Address = env.storage().instance().get(&ADMIN).unwrap();
admin.require_auth();

The function loads the administrator address that was stored during construction and requires its authorization, ensuring that only the administrator can trigger a deployment.

let deployed_address = env
   .deployer()
   .with_address(env.current_contract_address(), salt)
   .deploy_contract(ContractExecutable::Wasm(wasm_hash), constructor_args);

Uses the env.deployer() method to create a deployer object.
with_address(env.current_contract_address(), salt) specifies that the deployed contract’s address is derived from the Deployer contract’s own address and the given salt.
deploy_contract(ContractExecutable::Wasm(wasm_hash), constructor_args) deploys the contract using the provided Wasm bytecode hash, invokes its constructor with constructor_args, and returns the address of the newly deployed contract.

deployed_address

Returns the address of the newly deployed contract.

Build the contracts

To build the contract into a .wasm file, use the stellar contract build command. This command builds both the deployer contract and the test contract.

stellar contract build

Both .wasm files should be found in both contract target directories after building both contracts:

target/wasm32v1-none/release/soroban_deployer_contract.wasm

target/wasm32v1-none/release/soroban_deployer_test_contract.wasm

Run the contract

Before deploying the test contract with the deployer, install the test contract Wasm using the upload command. The upload command will print out the hash derived from the Wasm file which should be used by the deployer.

stellar contract upload \
--wasm  contract/target/wasm32v1-none/release/soroban_deployer_test_contract.wasm \
--source-account alice \
--network testnet

When deploying a smart contract to the network, you must specify an identity that will be used to sign the transactions. Change the alice identity to your own. The command prints out the hash as hex. It will look something like 6bc6d975ef99c057231481c40f69f4c2a8a89ac56e8826ef0378f8e5c6abc4be. We also need to deploy the Deployer contract. Since the Deployer contract’s __constructor function requires an administrator address, we provide the alice identity as the --admin argument. Create and provide your own identity, where necessary.

stellar contract deploy \
  --wasm deployer/target/wasm32v1-none/release/soroban_deployer_contract.wasm \
  --source-account alice  \
  --network testnet \
  -- --admin alice

This will return the deployer address. For example: CDKYZMA3OXR54YAHOQ5D4EWDFDT3ZNKKRYKQT7MGPWH22ZVD2DX2BJID. Then the deployer contract may be invoked with the Wasm hash value above. The constructor_args are passed through to the constructor of the deployed contract, so they are used here to set the initial value to 8.

stellar contract invoke \
  --id CDKYZMA3OXR54YAHOQ5D4EWDFDT3ZNKKRYKQT7MGPWH22ZVD2DX2BJID \
  --source-account alice \
  --network testnet \
  -- \
  deploy \
  --salt 123 \
  --wasm_hash 6bc6d975ef99c057231481c40f69f4c2a8a89ac56e8826ef0378f8e5c6abc4be \
  --constructor_args '[{"u32":8}]'

The deployer contract invocation will return the Contract address (For example: CCTVFX6BFTQHTGAHA5TY4YZQJRUKRE2RRNUTGVBNKE3PJF5C7CI53APY) of the newly deployed test contract. Invoke the deployed test contract using the address returned from the previous command.

stellar contract invoke \
  --id CCTVFX6BFTQHTGAHA5TY4YZQJRUKRE2RRNUTGVBNKE3PJF5C7CI53APY \
  --source-account alice \
  --network testnet \
  -- \
  value

You should receive something like the following output:

​Overview

​Prerequisites:

​Setup environment

​Code overview

​How it works

​Function breakdown

​Function steps

​Build the contracts

​Run the contract

Overview

Prerequisites:

Setup environment

Code overview

How it works

Function breakdown

Function steps

Build the contracts

Run the contract