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Deploying Tezos Contracts¶

If you're familiar with Truffle, then you already know about Truffle's deployment framework, called Migrations, used to manage deployment changes over time.

Overview¶

To deploy Tezos contracts, you'll first need to write migration scripts to tell Truffle how to deploy those contracts.

For the rest of this document, we'll be referring to deployment scripts as "migrations" to keep in line with Truffle's normal lingo. Keep in mind that a "migration" is synonymous with "deployment script".

Migrations¶

Migrations are JavaScript files that help you deploy contracts to a Tezos network. These files are responsible for staging and running your deployment tasks, and they're written under the assumption that your deployment needs will change over time (e.g., you'll add new scripts as time progresses, and your product matures).

Command¶

To run your migrations, run the following:

$ truffle migrate

This will run all migrations located within your project's migrations directory. At their simplest, migrations are simply a set of managed deployment scripts.

Migration files¶

A simple migration file looks like this:

Filename: 4_example_migration.js

var MyContract = artifacts.require("MyContract");

module.exports = (deployer) => {
  // deployment steps
  deployer.deploy(MyContract);
};

Note that the filename is prefixed with a number and is suffixed by a description. The numbered prefix is required to tell Truffle which order to run the scripts. The suffix is purely for human readability and comprehension.

artifacts.require()¶

At the beginning of the migration, we tell Truffle which contracts we'd like to interact with via the artifacts.require() method. This method is similar to Node's require, but in our case it specifically returns a contract abstraction that we can use within the rest of our deployment script. The name specified should match the naem of the source file, without the .ligo extension.

Consider this example where two contracts are specified within the same source file:

Filename: ./contracts/SimpleStorage.ligo

function main (const newValue : int;  const storedValue : int) : (list(operation) * int) is
  block { storedValue := newValue } with ((nil : list(operation)), storedValue)

To interact with this contract, in your deployment script, you'd use artifacts.require() like so:

var SimpleStorage = artifacts.require("SimpleStorage");

module.exports¶

All migrations must export a function via the module.exports syntax. The function exported of each migration should accept a deployer object as its first parameter. This object aides in deployment by both providing a clear syntax for deploying smart contracts as well as performing some of deployment's more mundane duties, such as saving deployed artifacts for later use. The deployer object is your main interface for staging deployment tasks, and its API is described at the bottom of this page.

Your migration function can accept other parameters as well. See the examples below.

Handling default values¶

A full migration script using SimpleStorage would look like the example below. Note that a default value (3) is passed to the deployer's deploy() function in order to set the contract's initial state. Note that the type of this second parameter must represent the type of state held in the contract, and should be represented in a form that is convertable from Javascript. More details on this below.

Coming from Ethereum? You'll notice that LIGO contracts lack constructors. Passing in default values as part of deployment is the only way to set the initial state of a contract. Constructors may be added to LIGO at a later date.

Filename: ./migrations/2_deploy_simple_storage.js

const SimpleStorage = artifacts.require("SimpleStorage");

module.exports = (deployer) => {
  deployer.deploy(SimpleStorage, 3);
};

From here, you can create new migrations with increasing numbered prefixes to deploy other contracts and perform further deployment steps.

Deployer¶

Your migration files will use the deployer to stage deployment tasks. As such, you can write deployment tasks synchronously and they'll be executed in the correct order:

// Stage deploying A before B
deployer.deploy(A);
deployer.deploy(B);

Alternatively, each function on the deployer can be used as a Promise, to queue up deployment tasks that depend on the execution of the previous task:

// Deploy A, then deploy B, passing in A's newly deployed address
deployer.deploy(A).then(function() {
  return deployer.deploy(B, A.address);
});

It is possible to write your deployment as a single promise chain if you find that syntax to be more clear. The deployer API is discussed at the bottom of this page.

Network considerations¶

It is possible to run deployment steps conditionally based on the network being deployed to. This is an advanced feature, so see the Networks section first before continuing.

To conditionally stage deployment steps, write your migrations so that they accept a second parameter, called network. Example:

module.exports = function(deployer, network) {
  if (network == "delphinet") {
    // Do something specific to the network named "delphinet".
  } else {
    // Perform a different step otherwise.
  }
}

Available accounts¶

Migrations are also passed the list of accounts set up in your wallet, for you to use during your deployments.

module.exports = function(deployer, network, accounts) {
  console.log(accounts);
  // => [ 'tz1iGB5P9bZkt356S2PYgAEUWCAuYEvwu152' ]

  // Example contract that takes in an owner as its default state.
  // In this case we use the same account we're using to deploy.
  deployer.deploy(OwnedContract, accounts[0]);
}

Deployer API¶

The deployer contains many functions available to simplify your migrations.

deployer.deploy(contract [, initialState] [, options])¶

Deploy a specific contract, specified by the contract object. This will set the address of the contract after deployment (i.e., Contract.address will equal the newly deployed address), and it will override any previous address stored.

This function takes an optional initial state as its second argument, that sets the state of your contract on chain when deployed. The type of data passed in this argument should match the type data stored in the state represented by the contract. We use the Taquito library to perform the translation from Javascript representation to types understood by Tezos. Please see their documentation for more information.

The last argument is an optional object that can include the key named overwrite. If overwrite is set to false, the deployer won't deploy this contract if one has already been deployed. This is useful for certain circumstances where a contract address is provided by an external dependency.

For more information, please see the @truffle/contract documentation.

Examples:

// Deploy a single contract without any initial state.
deployer.deploy(A);

// Deploy a single contract with an initial state of 3.
deployer.deploy(A, 3);

// Don't deploy this contract if it has already been deployed.
deployer.deploy(A, {overwrite: false});

// More specific example:
//
// Don't redeploy if the contract object represents an already-deployed dependency.
// If it has already been deployed to our target network, we can skip deploying it.
// This is useful for cases where we _do_ want to deploy that dependency for testing
// and development networks, but we don't want to replace it in production.
deployer.deploy(SomeDependency, {overwrite: false});

deployer.then(function() {...})¶

Just like a promise, run an arbitrary deployment step. Use this to call specific contract functions during your migration to add, edit and reorganize contract data.

Example:

var a, b;
deployer.then(function() {
  // Create a new version of A programatically, with 3 as the initial state.
  return A.new(3);
}).then(function(instance) {
  a = instance;
  // Get the deployed instance of B
  return B.deployed();
}).then(function(instance) {
  b = instance;
  // Send a transaction with the new instance of A's address using B's main() function.
  return b.main(a.address);
});