Algolia Observability

Overview

Algolia provides built-in analytics in the dashboard, but production systems need application-level observability: latency histograms, error rate counters, distributed traces, and alerts. This skill instruments the algoliasearch v5 client with Prometheus, OpenTelemetry, and structured logging.

Key Metrics to Track

Metric	Type	Why It Matters
Search latency (P50/P95/P99)	Histogram	User experience, SLA compliance
Search requests/sec	Counter	Capacity planning, cost tracking
Error rate by type	Counter	Detect API issues before users report
Index freshness (last updated)	Gauge	Data pipeline health
Record count	Gauge	Cost monitoring, data integrity

Instructions

Step 1: Instrumented Algolia Client Wrapper

// src/algolia/instrumented-client.ts
import { algoliasearch, ApiError } from 'algoliasearch';
import { Counter, Histogram, Gauge, Registry } from 'prom-client';

const registry = new Registry();

const searchLatency = new Histogram({
  name: 'algolia_search_duration_seconds',
  help: 'Algolia search request duration in seconds',
  labelNames: ['index', 'status'],
  buckets: [0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5],
  registers: [registry],
});

const searchTotal = new Counter({
  name: 'algolia_search_requests_total',
  help: 'Total Algolia search requests',
  labelNames: ['index', 'status'],
  registers: [registry],
});

const searchErrors = new Counter({
  name: 'algolia_errors_total',
  help: 'Total Algolia errors by type',
  labelNames: ['index', 'error_type', 'status_code'],
  registers: [registry],
});

const indexRecords = new Gauge({
  name: 'algolia_index_records',
  help: 'Number of records in Algolia index',
  labelNames: ['index'],
  registers: [registry],
});

const client = algoliasearch(process.env.ALGOLIA_APP_ID!, process.env.ALGOLIA_ADMIN_KEY!);

export async function instrumentedSearch<T = any>(
  indexName: string,
  searchParams: Record<string, any>
) {
  const timer = searchLatency.startTimer({ index: indexName });

  try {
    const result = await client.searchSingleIndex<T>({ indexName, searchParams });
    timer({ status: 'success' });
    searchTotal.inc({ index: indexName, status: 'success' });
    return result;
  } catch (error) {
    timer({ status: 'error' });
    searchTotal.inc({ index: indexName, status: 'error' });

    if (error instanceof ApiError) {
      searchErrors.inc({
        index: indexName,
        error_type: error.status === 429 ? 'rate_limit' : 'api_error',
        status_code: String(error.status),
      });
    } else {
      searchErrors.inc({
        index: indexName,
        error_type: 'network',
        status_code: '0',
      });
    }
    throw error;
  }
}

// Periodic index stats collection (run every 5 minutes)
export async function collectIndexMetrics() {
  const { items } = await client.listIndices();
  for (const idx of items) {
    indexRecords.set({ index: idx.name }, idx.entries || 0);
  }
}

export { registry };

Step 2: Prometheus Metrics Endpoint

// src/api/metrics.ts (Express example)
import express from 'express';
import { registry, collectIndexMetrics } from '../algolia/instrumented-client';

const app = express();

app.get('/metrics', async (_req, res) => {
  res.set('Content-Type', registry.contentType);
  res.send(await registry.metrics());
});

// Collect index stats every 5 minutes
setInterval(collectIndexMetrics, 5 * 60 * 1000);

Step 3: OpenTelemetry Distributed Tracing

// src/algolia/tracing.ts
import { trace, SpanStatusCode, type Span } from '@opentelemetry/api';

const tracer = trace.getTracer('algolia-service', '1.0.0');

export async function tracedSearch<T>(
  indexName: string,
  query: string,
  searchParams: Record<string, any> = {}
): Promise<T> {
  return tracer.startActiveSpan(`algolia.search ${indexName}`, async (span: Span) => {
    span.setAttribute('algolia.index', indexName);
    span.setAttribute('algolia.query', query);
    span.setAttribute('algolia.hitsPerPage', searchParams.hitsPerPage || 20);

    try {
      const result = await client.searchSingleIndex<T>({
        indexName,
        searchParams: { query, ...searchParams },
      });

      span.setAttribute('algolia.nbHits', result.nbHits);
      span.setAttribute('algolia.processingTimeMS', result.processingTimeMS);
      span.setStatus({ code: SpanStatusCode.OK });
      return result as T;
    } catch (error: any) {
      span.setStatus({ code: SpanStatusCode.ERROR, message: error.message });
      span.recordException(error);
      throw error;
    } finally {
      span.end();
    }
  });
}

Step 4: Structured Logging

// src/algolia/logger.ts
import pino from 'pino';

const logger = pino({ name: 'algolia', level: process.env.LOG_LEVEL || 'info' });

export function logSearch(params: {
  index: string;
  query: string;
  nbHits: number;
  processingTimeMS: number;
  page: number;
  userId?: string;
}) {
  logger.info({
    event: 'algolia.search',
    index: params.index,
    query: params.query,
    hits: params.nbHits,
    latency_ms: params.processingTimeMS,
    page: params.page,
    user: params.userId,
  });
}

export function logSearchError(params: {
  index: string;
  query: string;
  error: string;
  statusCode?: number;
}) {
  logger.error({
    event: 'algolia.search.error',
    index: params.index,
    query: params.query,
    error: params.error,
    status_code: params.statusCode,
  });
}

Step 5: Alert Rules (Prometheus AlertManager)

# alerts/algolia.yml
groups:
  - name: algolia
    rules:
      - alert: AlgoliaHighErrorRate
        expr: |
          rate(algolia_errors_total[5m]) /
          rate(algolia_search_requests_total[5m]) > 0.05
        for: 5m
        labels: { severity: warning }
        annotations:
          summary: "Algolia error rate > 5% for 5 minutes"

      - alert: AlgoliaHighLatency
        expr: |
          histogram_quantile(0.95,
            rate(algolia_search_duration_seconds_bucket[5m])
          ) > 0.5
        for: 5m
        labels: { severity: warning }
        annotations:
          summary: "Algolia P95 search latency > 500ms"

      - alert: AlgoliaRateLimited
        expr: rate(algolia_errors_total{error_type="rate_limit"}[5m]) > 0
        for: 2m
        labels: { severity: critical }
        annotations:
          summary: "Algolia returning 429 rate limit errors"

      - alert: AlgoliaIndexStale
        expr: algolia_index_records == 0
        for: 10m
        labels: { severity: warning }
        annotations:
          summary: "Algolia index has 0 records — possible sync failure"

Grafana Dashboard Queries

# Search rate: rate(algolia_search_requests_total[5m])
# Error rate: rate(algolia_errors_total[5m]) / rate(algolia_search_requests_total[5m])
# P50 latency: histogram_quantile(0.5, rate(algolia_search_duration_seconds_bucket[5m]))
# P95 latency: histogram_quantile(0.95, rate(algolia_search_duration_seconds_bucket[5m]))
# Records per index: algolia_index_records

Error Handling

Issue	Cause	Solution
Missing metrics	Client not instrumented	Use instrumentedSearch wrapper
High cardinality	Too many label values	Don't use query text as label
Trace gaps	Missing context propagation	Ensure OTel context flows through async
Alert storms	Thresholds too sensitive	Add for: 5m minimum duration

Resources

• Prometheus Client
• OpenTelemetry JS
• Algolia Dashboard Analytics
• pino Logger

Next Steps

For incident response, see algolia-incident-runbook.