Creating a Core Validator on Google Compute Engine

This guide covers how to quickly set up a ZetaChain validator on Google Compute Engine (GCE). This is intended to help engineers get a node up and running quickly, and you should consider this a foundation to tailor to your needs.

Overview

You will need:

A dedicated service account
A VM instance on GCE
Recommended: A Cloud Storage bucket to cache critical files
Recommended: Two Secret Manager secrets, one for the keyring passphrase, one for the seed phrase

Service Account

The service account should have the following permissions on the project:

roles/storage.objectAdmin
roles/secretmanager.secretAccessor
roles/secretmanager.viewer
roles/secretmanager.secretVersionManager

We recommend using a dedicated service account for security, rather than using the default service account.

GCE Instance

For the VM we use:

n2-standard-4 (4 cores, 16GB RAM)
Ubuntu 24.04
20 GB boot disk ("balanced" persistent disk)
2x NVME disk (we'll configure these as a RAID array later)
Configure the service account (opens in a new tab) to the account created for the validator
Set the service account "access scope" to allow full access to all Cloud APIs
Set the "enable-oslogin" metadata to "true" to enable OS login (opens in a new tab)
Enable shielded VM (opens in a new tab)

For reference we use the following Terraform definition for the node, although note this will need to be adapted for other users. In particular it references a cloud-init configuration, which expects values such as:

chain_id: athens_7001-1
network: athens3
snapshot_host: https://testnet-fullnode.snapshots.zetachain.com/ (opens in a new tab)
snapshot: fullnode-snapshot-v20-H7341468-2024-10-22_20-03.tar
protocol_version: v22
node_version: v22.0.0

locals {
  moniker = "cw3-${var.env}-${var.zetachain_node_type}"
  static_labels = {
    chain-id = var.zetachain.chain_id
    # Mark the node as a sentry node, so its peers can find it.
    node-type = var.zetachain_node_type
  }
  variable_labels = var.ops_agent_policy != "" ? map("goog-ops-agent-policy", var.ops_agent_policy) : {}
}


resource "google_compute_instance" "zetachain_node" {
 name         = var.name
 project      = var.project
 machine_type = "n2-standard-4"
 zone         = var.zone

 boot_disk {
   initialize_params {
     image = "projects/ubuntu-os-cloud/global/images/ubuntu-2404-noble-amd64-v20241004"
     size  = "20"
     type  = "pd-standard"
   }
 }

 // Two local NVME disks
 scratch_disk {
   interface = "NVME"
 }
 scratch_disk {
   interface = "NVME"
 }

 service_account {
   email = var.service_account

   # allow usage of cloud apis
   scopes = ["https://www.googleapis.com/auth/cloud-platform"]
 }

 network_interface {
   network = var.network

   access_config {
     // Ephemeral public IP
   }
 }

 labels = merge(local.variable_labels, local.static_labels)

 metadata = {
   user-data = templatefile(
     "${path.module}/files/cloud-config.yaml.tmpl",

     {
       gcs_bucket_snapshots    = var.gcs_bucket_snapshots
       gcs_bucket_static       = var.gcs_bucket_static
       zetachain_chain_id      = var.zetachain.chain_id
       zetachain_network       = var.zetachain.network
       zetachain_snapshot_host = var.zetachain.snapshot_host
       zetachain_snapshot      = var.zetachain.snapshot
       zetachain_version       = var.zetachain.protocol_version
       zetacored_version       = var.zetachain.node_version
       moniker                 = jsonencode(local.moniker)
     }
   )

   # Enable engineers to log into the machine.
   enable-oslogin = "TRUE"

   # The chain ID of the Zetachain network to connect to.
   chain-id = var.zetachain.chain_id

 }

 shielded_instance_config {
   enable_secure_boot          = true
   enable_integrity_monitoring = true
 }
}

We use cloud-init to set up the node automatically, which we'll detail below.

Cloud Storage

We cache binaries in Cloud Storage so we are not dependent on external sources, and snapshots to reduce time to copy them to the node in case of recovery.

For resiliency we recommend a dual-region (opens in a new tab) bucket, selecting a region which includes the location the VM is deployed to.

Secrets

The seed phrase for the validator needs to be backed up in case it's required for recovery, and we recommend using Secret Manager for these backups. Further, the keychain on the node disk is secured by a passphrase, and backing up this passphrase to Secret Manager is a simple approach to allowing automated access.

Cloud Init

The cloud-init (opens in a new tab) configuration is responsible for setting up the blockchain node software, while we leave validator key creation and deposit for an operator to complete manually.

We break the initialization into the following scripts, which are written then executed by cloud-init:

Set up disk array
Install Go
Build and install Cosmovisor
Configure system limits for ZetaChain
Install zetacored
Configure zetacored node

The cloud-init configuration also writes the service configuration for zetacored, so it is started automatically on VM startup. Lastly, it creates a new user "zetachain" to run the node software under.

#cloud-config

package_update: true
package_upgrade: true
packages:
- curl
- git
- jq
- lz4
- build-essential
- unzip
- mdadm

users:
 - name: zetachain
   gecos: Zetachain
   lock_passwd: true

write_files:
- path: /etc/systemd/system/zetacored.service
 permissions: 0644
 owner: root
 content: |
   [Unit]
   Description=zetacored (running under Cosmovisor)
   After=multi-user.target
   StartLimitIntervalSec=0
   [Install]
   WantedBy=multi-user.target
   [Service]
   User=zetachain
   ExecStart=/usr/local/bin/cosmovisor run start --home /var/lib/zetacored/ --log_format json  --moniker ${moniker}
   Restart=on-failure
   RestartSec=3
   WorkingDirectory=/var/lib/zetacored/cosmovisor
   Environment="DAEMON_NAME=zetacored"
   Environment="DAEMON_HOME=/var/lib/zetacored"

   # Note that downloading binaries is enabled due to relatively short
   # release timescales for ZetaChain.
   Environment="DAEMON_ALLOW_DOWNLOAD_BINARIES=true"
   Environment="DAEMON_RESTART_AFTER_UPGRADE=true"
   Environment="DAEMON_DATA_BACKUP_DIR=/var/lib/zetacored"
   Environment="CLIENT_DAEMON_NAME=zetaclientd"
   Environment="CLIENT_SKIP_UPGRADE=false"
   Environment="CLIENT_START_PROCESS=false"
   Environment="UNSAFE_SKIP_BACKUP=true"
   Type=simple
   LimitNOFILE=262144

- path: /usr/local/bin/setup-disk-array.sh
 permissions: "0744"
 content: |
   #!/bin/bash

   # Set up the RAID arrays.
   mdadm --create /dev/md0 --level=0 --raid-devices=2 /dev/nvme0n1 /dev/nvme0n2
   mkfs.ext4 /dev/md0
   echo "Created /dev/md0"

   # Add an fstab entry for the data directory.
   mkdir -p /var/lib/zetacored
   UUID=`sudo blkid -o value -s UUID /dev/md0`
   echo "UUID=$UUID /var/lib/zetacored ext4 defaults 0 0" >> /etc/fstab

   echo "Created fstab entries for /var/lib/zetacored"

   # Reload the systemd service after fstab is updated.
   systemctl daemon-reload

   # Mount the directory.
   mount /var/lib/zetacored

- path: /usr/local/bin/configure-system-limits.sh
 permissions: "0744"
 content: |
   #!/bin/bash

   # Update system limits
   echo "* hard nproc  262144" >> /etc/security/limits.conf
   echo "* soft nproc  262144" >> /etc/security/limits.conf
   echo "* hard nofile 262144" >> /etc/security/limits.conf
   echo "* soft nofile 262144" >> /etc/security/limits.conf
   echo "fs.file-max=262144" >> /etc/sysctl.conf

- path: /usr/local/bin/configure-zetacored.sh
 permissions: "0744"
 content: |
   #!/bin/bash

   CONFIG_TOML="/var/lib/zetacored/config/config.toml"
   APP_TOML="/var/lib/zetacored/config/app.toml"

   # Fetch a file from Cloud Storage if available. If not available, fetch from or GitHub then cache in Cloud Storage.
   fetch_config () {
     gsutil cp gs://${gcs_bucket_static}/network-config/${zetachain_network}/$1 /var/lib/zetacored/config/$1
     if [ $? -eq 1 ]; then
       echo "Downloading $1 from GitHub"
       wget https://raw.githubusercontent.com/zeta-chain/network-config/main/${zetachain_network}/$1 -O /var/lib/zetacored/config/$1
       gsutil cp /var/lib/zetacored/config/$1 gs://${gcs_bucket_static}/network-config/${zetachain_network}/$1
     fi
   }

   # Initialize the Zetachain node.
   /usr/local/bin/zetacored init --home /var/lib/zetacored ${moniker} --chain-id ${zetachain_chain_id}
   if [ $? -eq 1 ]; then
     echo "Failed to initialize Zetachain node"
     exit 1
   fi

   # Copy the network configuration files from Cloud Storage if available.
   fetch_config app.toml
   fetch_config client.toml
   fetch_config config.toml
   fetch_config genesis.json

   # Set the external IP address
   external_address=$(wget -qO- eth0.me)
   sed -i.bak -e "s/^moniker *=.*/moniker = \"${moniker}\"/" $CONFIG_TOML
   sed -i.bak -e "s/^external_address *=.*/external_address = \"$external_address:26656\"/" $CONFIG_TOML

   # Set up initial binary for Cosmosvisor
   mkdir -p /var/lib/zetacored/cosmovisor/genesis/bin
   mkdir -p /var/lib/zetacored/cosmovisor/upgrades
   cp /usr/local/bin/zetacored /var/lib/zetacored/cosmovisor/genesis/bin/zetacored

   echo "Installed Zetachain node to Cosmosvisor"

   # Fetch the state snapshot.
   gsutil cp gs://${gcs_bucket_static}/snapshot/${zetachain_network}/${zetachain_snapshot} /var/lib/zetacored/snapshot.tar
   if [ $? -eq 1 ]; then
     echo "Downloading state snapshot from ${zetachain_snapshot_host}"

     wget ${zetachain_snapshot_host}${zetachain_snapshot} -O /var/lib/zetacored/snapshot.tar
     gsutil cp /var/lib/zetacored/snapshot.tar gs://${gcs_bucket_static}/snapshot/${zetachain_network}/${zetachain_snapshot}
   fi

   tar -xf /var/lib/zetacored/snapshot.tar -C /var/lib/zetacored
   rm /var/lib/zetacored/snapshot.tar

   # Set the keyring backend. https://docs.cosmos.network/v0.52/user/run-node/keyring
   /var/lib/zetacored/cosmovisor/genesis/bin/zetacored --home /var/lib/zetacored \
     config keyring-backend file

   # Change the ownership of the directories.
   chown -R zetachain:zetachain /var/lib/zetacored/config
   chown -R zetachain:zetachain /var/lib/zetacored/cosmovisor
   chown -R zetachain:zetachain /var/lib/zetacored/data

   # Start the Zetachain node.
   systemctl enable zetacored.service
   systemctl start zetacored.service

- path: /usr/local/bin/install-zetacored.sh
 permissions: "0744"
 content: |
   #!/bin/bash

   # Copy the Zetachain binary from Cloud Storage if available.
   echo "Attempting to download Zetachain binary from Cloud Storage"
   gsutil cp gs://${gcs_bucket_static}/binaries/${zetacored_version}/zetacored-linux-amd64 /usr/local/bin/zetacored
   if [ $? -eq 1 ]; then
     echo "Downloading Zetachain binary from GitHub"
     wget https://github.com/zeta-chain/node/releases/download/${zetacored_version}/zetacored-linux-amd64 -O /usr/local/bin/zetacored
     gsutil cp /usr/local/bin/zetacored gs://${gcs_bucket_static}/binaries/${zetacored_version}/zetacored-linux-amd64
   fi

   # Copy the Zetachain client binary to the Cosmovisor directory.
   mkdir -p /var/lib/zetacored/cosmovisor/genesis/bin
   mkdir -p /var/lib/zetacored/cosmovisor/upgrades/${zetachain_version}/bin
   cp /usr/local/bin/zetacored /var/lib/zetacored/cosmovisor/genesis/bin/zetacored
   cp /usr/local/bin/zetacored /var/lib/zetacored/cosmovisor/upgrades/${zetachain_version}/bin/zetacored

   chmod a+x /usr/local/bin/zetacored
   echo "Installed Zetachain binary"

- path: /usr/local/bin/install-go.sh
 permissions: "0744"
 content: |
   #!/bin/bash

   GO_VERSION="1.20"

   # Install Go
   curl -L -O "https://golang.org/dl/go$GO_VERSION.linux-amd64.tar.gz"
   sudo rm -rf /usr/local/go
   sudo tar -C /usr/local -xzf "go$GO_VERSION.linux-amd64.tar.gz"
   rm "go$GO_VERSION.linux-amd64.tar.gz"

- path: /usr/local/bin/install-cosmovisor.sh
 permissions: "0744"
 content: |
   #!/bin/bash

   # Build the Cosmovisor binary.
   /usr/local/go/bin/go install cosmossdk.io/tools/cosmovisor/cmd/cosmovisor@v1.5.0
   cp ~/go/bin/cosmovisor /usr/local/bin/
   echo "Built Cosmovisor"

# The following commands are run by cloud-init in the final boot stage: https://cloudinit.readthedocs.io/en/latest/reference/modules.html#runcmd
# Logs can be retrieved with `journalctl -u cloud-final.service`

runcmd:
- sudo /usr/local/bin/setup-disk-array.sh
- sudo /usr/local/bin/install-go.sh
- sudo /usr/local/bin/install-cosmovisor.sh
- sudo /usr/local/bin/configure-system-limits.sh
- sudo /usr/local/bin/install-zetacored.sh
- sudo /usr/local/bin/configure-zetacored.sh

Validator Setup

Configuring the node as a validator is currently performed manually once the node is up and running. Before deploying the validator, ensure that the node is fully synced by comparing the block number in the logs with the block height on an explorer such as ZetaScan (opens in a new tab).

The key steps configuring the validator are:

Check node is synced
Create key
Backup seed phrase to Secret Manager
Transfer funds to the wallet for the validator node
Deposit to create the validator on chain

Check Node Is Synced

You can access the node logs with a command such as:

sudo -u zetachain journalctl -f -u zetacored.service

Look for a log entry such as the one following, where you can see "height":7559702:

Nov 06 22:32:53 athens3-us-south1-b-validator cosmovisor[485856]: {"level":"info","module":"server","server":"node","module":"state","height":7559702,"num_txs":4,"app_hash":"00A3F5A42D9D8C10D84447A6D085DFEB7D5CB9F62FB0A842F859C8529B2C3168","time":"2024-11-06T22:32:53Z","message":"committed state"}

Create/Restore Key

To create the private key for the validator, run the command:

sudo /var/lib/zetacored/cosmovisor/current/bin/zetacored --home /var/lib/zetacored keys add operator --algo secp256k1

This will prompt for a passphrase to be used to secure the keyring. Keep a note of the passphrase you set.

This will then write out the public key and the seed phrase.

Backup Seed Phrase

To back up the seed phrase, we'll put it into a file on disk and then upload it using the gcloud command. First, ensure that new files are created without read-write permissions for group or other users, using umask 077. Then copy the seed phrase produced when generating the key, into a file on disk.

Use the gcloud secrets versions add command to upload the file to Secret Manager, for example:

gcloud secrets versions add my-secret \
            --data-file=seed_phrase.txt

Transfer Funds

You can retrieve the address of the newly created key with:

sudo /var/lib/zetacored/cosmovisor/current/bin/zetacored --home /var/lib/zetacored keys list

Have the funds for the validator sent to that address. You can check the balance once they're sent, with:

sudo /var/lib/zetacored/cosmovisor/current/bin/zetacored --home /var/lib/zetacored query bank balances $(/var/lib/zetacored/cosmovisor/current/bin/zetacored keys show operator -a)

Deposit

The final step is to send a deposit transaction to create the validator. You'll need to extract the ED25519 public key (note this is not the key displayed when adding a new key, above), with a command such as:

sudo -u mantrachain mantrachaind --home /var/lib/mantrachain tendermint show-validator | jq .key

You can then deposit to create the validator, replacing <KEY> with the ED25519 key, and <MONIKER> with the public identifier for the validator. You should also update the amount being deposited, and the chain ID:

sudo /var/lib/zetacored/cosmovisor/current/bin/zetacored --home /var/lib/zetacored tx staking create-validator \
  --amount=1000000000000000000azeta \
  --pubkey="{\"@type\":\"/cosmos.crypto.ed25519.PubKey\",\"key\":\"<KEY>\"}" \
  --moniker="<MONIKER>" \
  --chain-id=athens_7001-1 \
  --commission-rate="1.00" \
  --commission-max-rate="1.00" \
  --commission-max-change-rate="0.01" \
  --min-self-delegation="1000000" \
  --gas="auto" \
  --gas-adjustment=1.15 \
  --gas-prices="1.0azeta" \
  --from=operator

This will prompt for the keyring passphrase set when creating the key, and ask you to confirm the transaction. Once the transaction succeeds the validator is created on chain and can be confirmed in the ZetaChain Explorer (opens in a new tab).