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Validator-Set-Tutorial-1.md

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Configuring each node

In this first part, we will create all the files needed to bootstrap a local PoA based network. This includes creating the chain specification file (also called genesis) as well as the node's configuration files for Node0, Node1 and Alice.

The workflow of this tutorial is the following:

  • Using a fixed list of authorities, Node0 will be the only authority allowed to seal blocks at the genesis of the blockchain.
  • Alice will deploy a Validator Set contract using Remix. The contract will also only allow Node0 to seal blocks.
  • Node0 will plan a fork to switch from a fixed list of validators to the Validator Set contract deployed previously by Alice.
  • Alice, as the owner of the Validator Set contract will add Node1 as a validator additionally to Node0.

Find here the files that will be generated in the following sections.

1. Create the genesis file

All the nodes of this tutorial will run on an Aura-based blockchain. Create a directory to store all the configuration files at one place. Create Validator-set-tutorial.json file containing:

{
    "name": "Validator-set-tutorial",
    "engine": {
        "authorityRound": {
            "params": {
                "stepDuration": "5",
                "validators" : {
                    "multi": {
                        "0": {
                            "list": [""]
                        }
                    }
                }
            }
        }
    },
    "params": {
        "gasLimitBoundDivisor": "0x400",
        "maximumExtraDataSize": "0x20",
        "minGasLimit": "0x7A1200",
        "networkID" : "0x2323",
        "eip155Transition": 0,
        "validateChainIdTransition": 0,
        "eip140Transition": 0,
        "eip211Transition": 0,
        "eip214Transition": 0,
        "eip658Transition": 0,
        "eip150Transition": "0x0",
        "eip160Transition": "0x0",
        "eip161abcTransition": "0x0",
        "eip161dTransition": "0x0",
        "eip98Transition": "0x7fffffffffffff",
        "maxCodeSize": 24576,
        "maxCodeSizeTransition": "0x0"
    },
    "genesis": {
        "seal": {
            "authorityRound": {
                "step": "0x0",
                "signature": "0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
            }
        },
        "difficulty": "0x20000",
        "gasLimit": "0x7A1200"
    },
    "accounts": {
        "0x0000000000000000000000000000000000000001": { "balance": "1", "builtin": { "name": "ecrecover", "pricing": { "linear": { "base": 3000, "word": 0 } } } },
        "0x0000000000000000000000000000000000000002": { "balance": "1", "builtin": { "name": "sha256", "pricing": { "linear": { "base": 60, "word": 12 } } } },
        "0x0000000000000000000000000000000000000003": { "balance": "1", "builtin": { "name": "ripemd160", "pricing": { "linear": { "base": 600, "word": 120 } } } },
        "0x0000000000000000000000000000000000000004": { "balance": "1", "builtin": { "name": "identity", "pricing": { "linear": { "base": 15, "word": 3 } } } },
        "0x0000000000000000000000000000000000000005": { "builtin": { "name": "modexp", "activate_at": 0, "pricing": { "modexp": { "divisor": 20 } } } },
        "0x0000000000000000000000000000000000000006": { "builtin": { "name": "alt_bn128_add", "activate_at": 0, "pricing": { "linear": { "base": 500, "word": 0 } } } },
        "0x0000000000000000000000000000000000000007": { "builtin": { "name": "alt_bn128_mul", "activate_at": 0, "pricing": { "linear": { "base": 40000, "word": 0 } } } },
        "0x0000000000000000000000000000000000000008": { "builtin": { "name": "alt_bn128_pairing", "activate_at": 0, "pricing": { "alt_bn128_pairing": { "base": 100000, "pair": 80000 } } } }
    }
}

This genesis file is defining a network called Validator-set-tutorial with many parameters similar to the ones the Kovan Network has. You are encouraged to visit Aura consensus as well as the general chain specifications pages to understand the parameters used here. This genesis file is incomplete as we miss Node0's address in the list of validators. We will create it in the next steps.

2. Create and configure the validators' nodes

2.1 Create and configure Node0

Each node corresponds to an account. The authorities (Node0 at the beginning, then also Node1) seal blocks and sign them using their private key. Alice will send transactions and sign them as well. We will create an account for each of them.

All nodes will run on a single machine. We will need to handle the networking ports carefully to avoid conflicts.

To keep a better overview, we will use TOML files to handle each node's configuration.

Create the file node0.toml with the following content:

# File node0.toml

[parity]
chain = "Validator-set-tutorial.json"
base_path = "node0"

[network]
port = 30300
#bootnodes = []

[rpc]
disable = true

[websockets]
disable = true

[account]
#password = [""]

[mining]
#engine_signer = ""
reseal_on_txs = "none"
force_sealing = true

At this point in the tutorial, we miss the address and password file for Node0's account as well as the bootnodes' addresses corresponding to all the nodes that we will use in this tutorial. These fields are commented (notice the #) for the moment. Let's create an account for Node0 using the passwords: node0pwd.

To do this, simply run openethereum --config ./node0.toml account new using the passwords given above.

Loading config file from ./node0.toml
Please note that password is NOT RECOVERABLE.
Type password:    # type the password given above
Repeat password:  # type again 
0xa2922fec00bb29fe13d68e87f64b9ad1719ed64a

It will give you the address of the account we will use for Node0.

We will need to create a password file also for the node to be able to sign messages and seal blocks using this account.

Run the following command to create a file named node0.pwd containing the password node0pwd:

echo "node0pwd" > node0.pwd

We will use this address and password file right away in our node0.toml configuration file. Add and uncomment the address as engine_signer in the [mining] section and add the password file in the [account] section as follow:

[account]
password = ["node0.pwd"]

[mining]
engine_signer = "0xa2922fec00bb29fe13d68e87f64b9ad1719ed64a"
reseal_on_txs = "none"
force_sealing = true

2.2 Set Node0 as validator in the genesis

As explained previously, we wish to have Node0 as the unique validator for the beginning of the blockchain. Add Node0's address to the Validator-set-tutorial.json genesis file in the validators' list so that it looks as follow:

"validators" : {
    "multi": {
        "0": {
            "list": ["0xa2922fec00bb29fe13d68e87f64b9ad1719ed64a"]
        }
    }
}

This means that a fixed list of validators will be used from block 0. Node0's address is the only one authorised to seal blocks. To make sure the file is valid, launch Node0 using the command openethereum --config ./node0.toml and verify that you do not get any error in the console.

You should see lines like the following every 5s:

Imported #1 0x4947…92ef (0 txs, 0.00 Mgas, 0 ms, 0.57 KiB)

This assesses that blocks are generated.

You should also copy in a text file the Public node address as we will use it later on. It looks like the following:

Public node URL: enode://dd87dbdb2ce7eec42cc4655a3e5abe12cdd0ede81b44f5492c84c892a9b209d91f8f0fb12fca44a5206711ae91d68d6bd643a1a018e3f59de30cd0415691b91e@172.18.0.1:30300

2.3 Create and configure Node1

The configuration for Node1 looks very similar to the one from Node0.

Create the file node1.toml with the following content:

# File node1.toml

[parity]
chain = "Validator-set-tutorial.json"
base_path = "node1"

[network]
port = 30301
#bootnodes = []

[rpc]
disable = true

[websockets]
disable = true

[account]
#password = [""]

[mining]
#engine_signer = ""
reseal_on_txs = "none"
force_sealing = true

We are missing here also the address and password file for Node1's account as well as the bootnodes' addresses corresponding to all the nodes that we will use in this tutorial. These fields are commented (notice the #) for the moment. Let's create an account for Node1 using the passwords: node1pwd.

To do this, simply run openethereum --config ./node1.toml account new using the passwords given above.

Loading config file from ./node1.toml
Please note that password is NOT RECOVERABLE.
Type password:    # type the password given above
Repeat password:  # type again 
0x32784591c38bf8aa081e96ba4db462bd73a3179e

It will give you the address of the account we will use for Node1.

Although Node1 will not initially be part of the validator's list, we can still create a password file and configure the node as if it was a validator. It will not seal blocks as long as the account signing them is not part of the authorised validators. It will start sealing as soon as that it is added to the Validator Set.

Run the following command to create a file named node1.pwd containing the password node1pwd:

echo "node1pwd" > node1.pwd

We will use this address and password file right away in our node1.toml configuration file. Add and uncomment the address as engine_signer in the [mining] section and add the password file in the [account] section as follow:

[account]
password = ["node1.pwd"]

[mining]
engine_signer = "0x32784591c38bf8aa081e96ba4db462bd73a3179e"
reseal_on_txs = "none"
force_sealing = true

To make sure the file is valid, launch Node1 using the command openethereum --config ./node1.toml and verify that you do not get any error in the console. As Node1 and Node0 might not be connected to each other yet, it is normal that Node1 does not import any block from Node0.

Also, copy in a text file the Public node address as we will use is later on.

Public node URL: enode://70f8784653cb189b6e2daf925f25f1ca3dfad266370b6ddd258551e48159bd5b9c23bdd39367155136a0ee7d6331d4107c0a765850ccc706c37686baefb039a1@172.18.0.1:30301

3. Create and configure Alice's node

Alice's node configuration will be slightly different than the two validator's nodes that we have created previously. It will not need any [mining] section. We will use the standard ports for HTTP and WebSockets RPCs so that Alice's node can be easily connected to the tools used later such as Remix.

Create the file alice.toml with the following content:

# File alice.toml

[parity]
chain = "Validator-set-tutorial.json"
base_path = "alice"

[network]
port = 30303
#bootnodes = []

[rpc]
port = 8545                             # Enable HTTP JSON RPC on the standard port
apis = ["eth","net"]
cors = ["https://remix.ethereum.org"]   # allow Remix to connect to this node

[websockets]
disable = false                         # Enable WS JSON RPC on the standard port
port = 8546
interface = "local"

We are missing here also the address and password file for Alice's account as well as the bootnodes' addresses corresponding to all the nodes that we will use in this tutorial. Let's create an account for Alice using the passwords: alicepwd.

To do this, simply run openethereum --config ./alice.toml account new using the passwords given above.

Loading config file from ./alice.toml
Please note that password is NOT RECOVERABLE.
Type password:    # type the password given above
Repeat password:  # type again 
0x12db1ee91481573302f63ebf3d735820081c68a2

It will give you the address of the account we will use for Alice.

We will need to create a password file also for the account to be autonomously usable by the node.

Run the following command to create a file named alice.pwd and containing the password alicepwd:

echo "alicepwd" > alice.pwd

We will use this address and password file right away in our alice.toml configuration file. Add an [account] section as follow.

[account]
unlock = ["0x12db1ee91481573302f63ebf3d735820081c68a2"]      # Alice's account to sign transactions from Remix.
password = ["alice.pwd"]

To make sure the file is valid, launch Alice's node using the command openethereum --config ./alice.toml and verify that you do not get any error in the console. Also, copy in a text file the Public node address as we will use is later on. It should look similar to:

Public node URL: enode:////20d155e5b7279055257ae20d6c0e1a3935dc38cbc941fc5039d1b889e298ce34b5e9f082c84d3f1394984b341553a9ae426ce4372f33efc83b98afa50f51c3aa@172.18.0.1

4. Add bootnodes to each configuration file

We now have copied all the public URLs (enodes) of our nodes. We will use them to connect the nodes between each other so that we do not need to wait for them to discover themselves organically.

Uncomment and add the list of nodes to Node0.toml, Ǹode1.toml and Alice.toml so that each file contains lines similar to:

bootnodes = [
"enode://dd87dbdb2ce7eec42cc4655a3e5abe12cdd0ede81b44f5492c84c892a9b209d91f8f0fb12fca44a5206711ae91d68d6bd643a1a018e3f59de30cd0415691b91e@172.18.0.1:30300", # Node0
"enode://70f8784653cb189b6e2daf925f25f1ca3dfad266370b6ddd258551e48159bd5b9c23bdd39367155136a0ee7d6331d4107c0a765850ccc706c37686baefb039a1@172.18.0.1:30301", # Node1
"enode://20d155e5b7279055257ae20d6c0e1a3935dc38cbc941fc5039d1b889e298ce34b5e9f082c84d3f1394984b341553a9ae426ce4372f33efc83b98afa50f51c3aa@172.18.0.1:30303"  # Alice
]

To make sure that each node sees the others, launch the nodes simultaneously in different terminal windows and verify that they are each connected to 2 peers and importing the blocks created by Node0.

Find here example files that you can compare yours with.

| ← Validator Set Tutorial Overview | Part 2 - Deploy the Validator Set contract → |