Run a Gully Sentry watcher in 5 minutes

The watcher checks every assertion GullyChain posts to Arbitrum Sepolia against your own view of the chain, and signs a heartbeat for your key every 10 minutes. It needs Docker (or Node.js 20+), about 100 MB of memory and no funds. The full guide is Gully Sentry: claim, run, check.

#1. Claim your free key (1 minute)

Open sentry.gullychain.xyz, press Connect wallet to claim and follow the steps. You sign one message; Gully Labs pays the mint gas. Note your key number (for example 12).

#2. Download the watcher and make its hot key (1 minute)

mkdir gully-sentry && cd gully-sentry
curl -fsSLO https://sentry.gullychain.xyz/downloads/gully-sentry.mjs
curl -fsSL https://sentry.gullychain.xyz/downloads/gully-sentry.mjs.sha256 | sha256sum -c -
docker run --rm -v gully-sentry:/data -v "$PWD/gully-sentry.mjs:/app/gully-sentry.mjs:ro" \
  -e SENTRY_KEY_FILE=/data/operator.key node:22-alpine node /app/gully-sentry.mjs init

init prints an operator address. That hot key only signs heartbeats; your Sentry Key never leaves your wallet. On Windows, check the file with (Get-FileHash .\gully-sentry.mjs -Algorithm SHA256).Hash.ToLower().

#3. Delegate your key (1 minute)

On Run a sentry, step 2, enter your key number and the operator address and press Delegate: one transaction from the wallet that holds the key. You can change or remove the operator at any time.

#4. Start the watcher (one command)

Replace <your key> with your key number:

docker run -d --restart unless-stopped --name gully-sentry -v gully-sentry:/data \
  -v "$PWD/gully-sentry.mjs:/app/gully-sentry.mjs:ro" \
  -e SENTRY_KEY_FILE=/data/operator.key -e SENTRY_CONFIG=/data/gully-sentry.json \
  -e SENTRY_KEY_CONTRACT=0xa24bF9f0eA1AE5F5226d8F7e714cEa3537aa30Ac -e SENTRY_TOKEN_IDS=<your key> \
  node:22-alpine node /app/gully-sentry.mjs run

No Docker? With Node.js 20+: node gully-sentry.mjs init, then SENTRY_KEY_CONTRACT=0xa24bF9f0eA1AE5F5226d8F7e714cEa3537aa30Ac SENTRY_TOKEN_IDS=<your key> node gully-sentry.mjs run.

For the strongest check, point it at a node you trust: add -e SENTRY_L3_RPC=https://rpc.gullyrpc.xyz/<project>/evm/485590 (Gully RPC (opens in a new tab)) or the URL of your own Nitro node.

#5. See your uptime (within 10 minutes)

• docker logs -f gully-sentry shows each heartbeat and its verdict (ok, mismatch, stale or unreachable).
• Run a sentry, step 4 Check my key, shows your key's last heartbeat.
• The operator leaderboard ranks keys by uptime over 24 hours and 7 days. It shows your .gully name if you have one, otherwise a short address.

Uptime is the share of 10-minute slots in which your watcher sent a usable heartbeat. Keep the container running (--restart unless-stopped brings it back after a reboot) to stay near 100%.