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Indexer Health Check

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Description

Section titled “Description”

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

Prerequisites

Section titled “Prerequisites”
  • LocalNet running (via algokit localnet start)

Run This Example

Section titled “Run This Example”

From the repository root:

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

Code

Section titled “Code”

View source on GitHub

01-health-check.ts
/**
 * 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);
});

Other examples in Indexer Client

Section titled “Other examples in Indexer Client”