Validator-Set-Tutorial-2.md

title	Deploy the Validator Set contract

Now that every node is configured, and either creates or imports blocks, we can create and deploy a Validator Set contract. The following steps assume that Node0, Node1 and Alice nodes are running. In this tutorial, Alice will deploy and be the owner of the contract. In a real world setting, Alice could be replaced by a multi-signature contract or any other governing logic, so as to prevent one single entity from controlling the Validator Set.

1. Setup Remix and remixd

The Validator Set contract used for Kovan Network is in fact a set of contracts. We will first download them locally before using remixd and Remix to deploy this set of contracts. remixd is a convenient way to load local files to Remix and avoid tedious manual work. Explaining how to install remixd is outside of the scope of this tutorial. Please install it with npm, and we'll continue from there.

• Run the following command to copy the Validator Set contract's repository and navigate to the contract's directory:

git clone https://github.com/openethereum/kovan-validator-set.git && cd ./kovan-validator-set/contracts

• Launch remixd from here to share the content of this directory with Remix:

remixd -s ./

This opens a WebSockets channel to allow your browser to access local files on the port 65520.

• Visit Remix and verify that you can see your local file by clicking on the link symbol in the top left corner. If the connection is successful, you should see your local files.

We will now connect remix to Alice's node. We've set it up earlier to accept connections from Remix domain over the standard JSON RPC HTTP port 8545.

• In Remix, click on the Run tab in the top right-hand corner of the window.
• Select Web3 provider in the "Environment" drop-down menu.
• Use the default "http://localhost:8545" as it is the port we specified in alice.toml.
• You should see Alice's account in the next drop-down menu.

2. Deploy RelaySet and RelayedOwnedSet

The contract used in this tutorial is not trivial to understand as it consists of a set of contracts using a proxy as well as libraries. You can read more about the internals in the dedicated repository. The important concept to understand is that RelaySet is a proxy contract that will point to the main contract that itself allows to add and remove validators. Proxy contracts allow to be flexible and update the "proxied" contract in the future if needed. In our case, RelayedOwnedSet will be the "proxied" contract.

We will need to deploy RelaySet, then deploy RelayedOwnedSet, and finally, link the former with the later.

• Deploy RelaySet by selecting it in the drop-down menu on the right part of Remix and click Deploy.
• If the transaction is successful, the RelaySet contract is deployed, copy its address.
• Now select RelayedOwnedSet in the drop-down menu. The constructor requires two arguments, the RelaySet address and the initial set of validators (this is an array).
• Deploy RelayedOwnedSet by filling the parameters with the address copied at the previous step, and Node0's address. It should look similar to (notice that the array ["0x.."] for _initial parameter):
• Finally, call the setRelay function from RelaySet contract to link the proxied with the proxy contract.

The Validator Set contract is now deployed. You can make sure Node0 is the only allowed validator by calling getValidators.

| ← Part 1 - Configuring each node | Part 3 - Hardfork to use the Validator Set contract → |