feat: chain uptime monitor

package.json

@@ -9,6 +9,7 @@
     "retryable-monitor": "yarn workspace retryable-monitor dev",
     "batch-poster-monitor": "yarn workspace batch-poster-monitor dev",
     "assertion-monitor": "yarn workspace assertion-monitor dev",
+    "chain-uptime-monitor": "yarn workspace chain-uptime-monitor dev",
     "test": "vitest"
   },
   "devDependencies": {

packages/chain-uptime-monitor/README.md

@@ -0,0 +1,83 @@
+# Chain Uptime Monitor
+
+A simple, efficient module for monitoring Arbitrum chain uptime by pinging RPC endpoints.
+
+## Overview
+
+The Chain Uptime Monitor checks if Arbitrum chains are running by attempting to fetch the latest block number from their RPC endpoints. It provides a modular, SDK-like approach with callbacks for success and error scenarios.
+
+## Features
+
+- ✅ Simple RPC health check via `getBlockNumber()`
+- 🔔 Slack alerts only for down chains (consolidated by default)
+- 📊 Summary reporting
+- 🔌 Modular design with callbacks for extensibility
+- ⚡ Concurrent chain checking
+- 🎯 Configurable timeout (default: 10 seconds)
+
+## Usage
+
+### CLI
+
+```bash
+# Basic usage
+yarn chain-uptime-monitor
+
+# With custom config path
+yarn chain-uptime-monitor --configPath ./custom-config.json
+
+# With Slack alerting enabled (consolidated alerts by default)
+yarn chain-uptime-monitor --enableAlerting
+
+# With individual alerts per chain (disable consolidation)
+yarn chain-uptime-monitor --enableAlerting --no-consolidateAlerts
+```
+
+## Configuration
+
+The monitor uses the same `config.json` format as other monitors:
+
+```json
+{
+  "childChains": [
+    {
+      "name": "Arbitrum Sepolia",
+      "chainId": 421614,
+      "parentChainId": 11155111,
+      "orbitRpcUrl": "https://sepolia-rollup.arbitrum.io/rpc",
+      "explorerUrl": "https://sepolia.arbiscan.io",
+      "parentExplorerUrl": "https://sepolia.etherscan.io"
+    }
+  ]
+}
+```
+
+## Environment Variables
+
+- `CHAIN_UPTIME_MONITORING_SLACK_TOKEN`: Slack bot token for alerts
+- `CHAIN_UPTIME_MONITORING_SLACK_CHANNEL`: Slack channel ID for alerts
+
+## Options
+
+- `--configPath`: Path to configuration file (default: "config.json")
+- `--enableAlerting`: Enable Slack alerts (default: false)
+- `--consolidateAlerts`: Consolidate all alerts into a single message (default: true)
+  - When `true` (default): Sends **one consolidated summary message** at the end with all down chains listed. No individual alerts are sent during chain checks.
+  - When `false` (`--no-consolidateAlerts`): Sends **individual Slack messages** immediately when each chain goes down. No consolidated summary is sent.
+
+## Output
+
+The monitor provides:
+
+- Console logs for each chain check (both up and down)
+- Summary statistics (total, up, down)
+- Exit code 1 if any chains are down
+- Slack alerts (if enabled):
+  - **Only alerts for down chains** - no alerts sent if all chains are up
+  - **Consolidated mode (`--consolidateAlerts`, default)**:
+    - Waits until all chains are checked
+    - Sends **one summary message** with total chains, up/down counts, and list of all down chains
+    - Example: "❌ Chain Uptime Alert\n\nTotal Chains: 4\n✅ Up: 3\n❌ Down: 1\n\nDown Chains:\n - Chain 2 (1002): Connection timeout"
+  - **Individual mode (`--no-consolidateAlerts`)**:
+    - Sends **separate message for each down chain** immediately when detected
+    - Example: "❌ Chain Uptime Alert: Chain 2 (Chain ID: 1002) is DOWN\nError: Connection timeout\n..."