# Deploying Smart Contracts

The agoric deploy command in the Agoric command line tool supports deploying contracts and off-chain web applications that talk to those contracts. The command has two primary uses:

  • Deploy smart contract source code onto the blockchain.
  • Deploy and set up an application program on a local server running an Agoric process.

Use the agoric deploy command to run your dapp's contract/deploy.js and api/deploy.js scripts. You can use the deploy scripts copied from an existing Dapp as they are, or you can modify them as suggested later in this document.

Remember, your Dapp has three primary subdirectories:

  • contract/ contains files defining your on-chain smart contract.
  • api/ contains files enabling the UI frontend to communicate via HTTP/WebSocket to an on-chain backend contract instance and start your Dapp contract instance and backend.
  • ui/ contains files relating to your contract's browser user interface.

# How It Works

All deployment happens via the local running Agoric process. This is usually the ag-solo process, sometimes described as an Agoric VM or a local server.

ag-solo communicates with either a locally running or remote chain. The local process has a home object, which contains references to services on-chain that can be used to call associated API commands. Such references include zoe, the board for sharing objects, and the application user's wallet.

Each deploy.js runs in its own temporary process connected to ag-solo, through which it can reach the chain. It first uploads bundled contract source code to ag-solo, then goes through the home object to access zoe and uses that to install the code on-chain.

All on-chain commands that deployment scripts use to deploy contracts and Dapps are also available to developers via the REPL associated with their wallet.

# Contract Deployment

First, let's look at contract deployment. contract/deploy.js bundles up a contract's source code (which may consist of multiple files and modules) and "installs" it on the blockchain as source code, using Zoe. This does not execute contract code; it just makes the code available on-chain.

The contract deployment process uses zoe.install() to install the contract source code on-chain. This returns an installation associated with the source code. In a typical contract deployment, the deploy script adds the installation to the default shared board so it is broadly accessible on the chain. The script then writes the board id to a config file in the Dapp's ui directory as shown below.

By default, when you run agoric init, your dapp gets the dapp-fungible-faucet contract/deploy.js file (opens new window), which is our example of a typical contract deploy script.

Deploying the dapp-fungible-faucet contract (e.g., with agoric deploy contract/deploy.js after agoric init copied it into a local directory) installs it on chain, and generates the file ui/public/conf/installationConstants.js with contents like:

// GENERATED FROM dapp-fungible-faucet/contract/deploy.js
export default {
    "CONTRACT_NAME": "fungibleFaucet",
    "INSTALLATION_BOARD_ID": "1456154132"

The board provides a unique ID per object, in this case "1456154132", so it is different for each contract deployment.

# Application Service Deployment and Setup

Next, let's look at application deployment and setup. As compared to contract deployment, you need to customize the Agoric API server deployment and setup much more for your particular application and contract. Some Dapps use a singleton contract instance which presumes that it will be installed once and serve all customers (as opposed to an auction or swap contract, which is installed once, but instantiated separately for each sale it manages). A singleton may need to:

  • Be instantiated
  • Find and connect to on-chain resources such as issuers for specific currencies
  • Create new on-chain resources like new currencies or NFTs
  • Create new Purses for the application to use
  • Seed the on-chain contract instance with initial orders or configuration.

These example contract api/deploy.js scripts show some of the range of the above custom setup actions:

Application deployment steps may include:

  • Bundle the api/ code and deploy it to the running local ag-solo
  • Include the contract installation configuration information in the bundle
  • Create new currencies and add them to the application's wallet

Steps for contracts that use a singleton instance for all clients may further include:

  • Instantiate a contract instance using the installation created by contract deployment
  • Use the invitation from that instance creation to configure the new instance
  • Register the contract instance's instance with the Board
  • Record the contract instance's Board ID in a configuration file