Indexer Health Check

Description

This example demonstrates how to check indexer health status using the IndexerClient healthCheck() method.

Prerequisites

LocalNet running (via algokit localnet start)

Run This Example

From the repository root:

cd examples
npm run example indexer_client/01-health-check.ts

Code

View source on GitHub

/**
 * Example: Indexer Health Check
 *
 * This example demonstrates how to check indexer health status using
 * the IndexerClient healthCheck() method.
 *
 * Prerequisites:
 * - LocalNet running (via `algokit localnet start`)
 */

import { createIndexerClient, printError, printHeader, printInfo, printStep, printSuccess } from '../shared/utils.js'

async function main() {
  printHeader('Indexer Health Check Example')

  // Create an Indexer client connected to LocalNet
  const indexer = createIndexerClient()

  // =========================================================================
  // Step 1: Perform Health Check
  // =========================================================================
  printStep(1, 'Checking indexer health with healthCheck()')

  try {
    // healthCheck() returns a HealthCheck object with status information
    const health = await indexer.healthCheck()

    printSuccess('Indexer is healthy!')
    printInfo('')
    printInfo('Health check response:')
    printInfo(`  - version: ${health.version}`)
    printInfo(`  - dbAvailable: ${health.dbAvailable}`)
    printInfo(`  - isMigrating: ${health.isMigrating}`)
    printInfo(`  - message: ${health.message}`)
    printInfo(`  - round: ${health.round}`)

    // Display errors if any
    if (health.errors && health.errors.length > 0) {
      printInfo(`  - errors: ${health.errors.join(', ')}`)
    } else {
      printInfo('  - errors: none')
    }

    // =========================================================================
    // Step 2: Interpret the Health Check Results
    // =========================================================================
    printStep(2, 'Interpreting health check results')

    // Check if the database is available
    if (health.dbAvailable) {
      printSuccess('Database is available and accessible')
    } else {
      printError('Database is NOT available')
    }

    // Check if a migration is in progress
    if (health.isMigrating) {
      printInfo('Note: Database migration is in progress')
      printInfo('Some queries may be slower or unavailable during migration')
    } else {
      printSuccess('No database migration in progress')
    }

    // Display current round
    printInfo(`Indexer has processed blocks up to round ${health.round}`)
  } catch (error) {
    printError(`Health check failed: ${error instanceof Error ? error.message : String(error)}`)
    printInfo('')
    printInfo('Common causes of health check failures:')
    printInfo('  - Indexer service is not running')
    printInfo('  - Network connectivity issues')
    printInfo('  - Incorrect indexer URL or port')
    printInfo('')
    printInfo('To start LocalNet, run: algokit localnet start')
  }

  // =========================================================================
  // Summary
  // =========================================================================
  printHeader('Summary')
  printInfo('This example demonstrated:')
  printInfo('  1. healthCheck() - Checks if the indexer service is healthy')
  printInfo('')
  printInfo('Health check response fields explained:')
  printInfo('  - version: The version of the indexer software')
  printInfo('  - dbAvailable: Whether the database is accessible')
  printInfo('  - isMigrating: Whether a database migration is in progress')
  printInfo('  - message: A human-readable status message')
  printInfo('  - round: The latest block round the indexer has processed')
  printInfo('  - errors: Any error messages from the indexer')
}

main().catch((error) => {
  console.error('Fatal error:', error)
  process.exit(1)
})

Indexer Health Check

Description

Prerequisites

Run This Example

Code

Other examples in Indexer Client