Algolia Reference Architecture

Overview

Production-ready architecture for Algolia-powered search. Covers index design, data pipeline from source to Algolia, service layer patterns, and frontend integration.

Architecture Overview

┌──────────────────────────────────────────────────────────────┐
│                      Frontend                                 │
│  InstantSearch.js / React InstantSearch                       │
│  Uses: liteClient (search-only key)                          │
│  Sends: search-insights events (clicks, conversions)          │
└───────────────────────┬──────────────────────────────────────┘
                        │ Search + Events
                        ▼
┌──────────────────────────────────────────────────────────────┐
│                   Algolia Cloud                               │
│  ┌─────────┐  ┌──────────────┐  ┌─────────────┐             │
│  │ Search   │  │ Analytics    │  │ Recommend   │             │
│  │ Engine   │  │ + Insights   │  │ (ML-based)  │             │
│  └─────────┘  └──────────────┘  └─────────────┘             │
└───────────────────────▲──────────────────────────────────────┘
                        │ Indexing (admin key)
                        │
┌──────────────────────────────────────────────────────────────┐
│                    Backend Service                            │
│  ┌────────────┐  ┌──────────────┐  ┌─────────────────┐      │
│  │ Search     │  │ Indexing     │  │ Settings        │      │
│  │ Service    │  │ Pipeline     │  │ Manager         │      │
│  └────────────┘  └──────┬───────┘  └─────────────────┘      │
│                         │                                     │
│  ┌──────────────────────▼────────────────────────────┐       │
│  │              Source Database                        │       │
│  │  PostgreSQL / MongoDB / CMS / External API          │       │
│  └────────────────────────────────────────────────────┘       │
└──────────────────────────────────────────────────────────────┘

Project Structure

src/
├── algolia/
│   ├── client.ts           # Singleton client (see algolia-sdk-patterns)
│   ├── indices.ts          # Index name constants + environment prefixing
│   ├── settings/
│   │   ├── products.ts     # Products index settings
│   │   ├── articles.ts     # Articles index settings
│   │   └── apply.ts        # Script to apply all settings
│   └── transforms/
│       ├── product.ts      # DB record → Algolia record transformer
│       └── article.ts      # DB record → Algolia record transformer
├── services/
│   ├── search.ts           # Search service (wraps Algolia client)
│   └── indexing.ts         # Indexing pipeline (DB → transform → Algolia)
├── api/
│   ├── search.ts           # Search endpoint (returns Algolia results)
│   └── reindex.ts          # Admin endpoint to trigger reindex
└── jobs/
    └── sync-algolia.ts     # Cron job for periodic full sync

Index Design Patterns

Pattern 1: One Index Per Entity Type

// src/algolia/indices.ts
const ENV = process.env.NODE_ENV === 'production' ? '' : `${process.env.NODE_ENV}_`;

export const INDICES = {
  products:  `${ENV}products`,
  articles:  `${ENV}articles`,
  faq:       `${ENV}faq`,
  users:     `${ENV}users`,     // Internal search only (never expose to frontend)
} as const;

export type IndexName = typeof INDICES[keyof typeof INDICES];

Pattern 2: Record Transformer (Source → Algolia)

// src/algolia/transforms/product.ts
import type { Product } from '../db/types';

interface AlgoliaProduct {
  objectID: string;
  name: string;
  description: string;
  category: string;
  brand: string;
  price: number;
  rating: number;
  review_count: number;
  in_stock: boolean;
  image_url: string;
  _tags: string[];        // Algolia convention: filterable tags
}

export function transformProduct(product: Product): AlgoliaProduct {
  return {
    objectID: product.id,
    name: product.name,
    description: product.description?.substring(0, 5000) || '',  // Truncate
    category: product.category.name,
    brand: product.brand.name,
    price: product.price / 100,                  // Cents → dollars
    rating: product.avgRating,
    review_count: product.reviewCount,
    in_stock: product.inventory > 0,
    image_url: product.images[0]?.url || '',
    _tags: [
      product.category.slug,
      ...(product.isFeatured ? ['featured'] : []),
      ...(product.isNew ? ['new-arrival'] : []),
    ],
  };
}

Pattern 3: Settings as Code

// src/algolia/settings/products.ts
import type { IndexSettings } from 'algoliasearch';

export const productSettings: IndexSettings = {
  searchableAttributes: [
    'name',
    'brand',
    'category',
    'unordered(description)',
  ],
  attributesForFaceting: [
    'searchable(brand)',
    'category',
    'filterOnly(price)',
    'filterOnly(in_stock)',
    '_tags',
  ],
  customRanking: ['desc(review_count)', 'desc(rating)'],
  attributesToRetrieve: ['name', 'brand', 'price', 'image_url', 'category', 'rating'],
  attributesToHighlight: ['name', 'description'],
  attributesToSnippet: ['description:30'],
  unretrievableAttributes: ['_tags'],
  distinct: 1,
  attributeForDistinct: 'product_group_id',
  replicas: [
    'virtual(products_price_asc)',
    'virtual(products_price_desc)',
    'virtual(products_newest)',
  ],
};

// src/algolia/settings/apply.ts
import { getClient } from '../client';
import { INDICES } from '../indices';
import { productSettings } from './products';

async function applyAllSettings() {
  const client = getClient();
  await client.setSettings({ indexName: INDICES.products, indexSettings: productSettings });
  console.log('All Algolia settings applied');
}

Pattern 4: Search Service Layer

// src/services/search.ts
import { getClient } from '../algolia/client';
import { INDICES } from '../algolia/indices';
import { ApiError } from 'algoliasearch';

export class SearchService {
  private client = getClient();

  async searchProducts(params: {
    query: string;
    filters?: string;
    facetFilters?: string[][];
    page?: number;
    hitsPerPage?: number;
  }) {
    try {
      return await this.client.searchSingleIndex({
        indexName: INDICES.products,
        searchParams: {
          query: params.query,
          filters: params.filters,
          facetFilters: params.facetFilters,
          page: params.page ?? 0,
          hitsPerPage: params.hitsPerPage ?? 20,
          facets: ['category', 'brand'],
          clickAnalytics: true,
        },
      });
    } catch (error) {
      if (error instanceof ApiError && error.status === 404) {
        return { hits: [], nbHits: 0, nbPages: 0, page: 0 };
      }
      throw error;
    }
  }

  async federatedSearch(query: string) {
    const { results } = await this.client.search({
      requests: [
        { indexName: INDICES.products, query, hitsPerPage: 5 },
        { indexName: INDICES.articles, query, hitsPerPage: 3 },
        { indexName: INDICES.faq, query, hitsPerPage: 3 },
      ],
    });
    return results;
  }
}

Error Handling

Issue	Cause	Solution
Circular dependency	Service imports client imports service	Use lazy initialization
Config drift	Dashboard edits not in code	Apply settings from code in CI
Transform errors	DB schema change	Add validation in transformer
Index name typo	Hardcoded strings	Use INDICES constants

Resources

• Algolia Architecture Guide
• Index Design Best Practices
• Multi-Index Search

Next Steps

For multi-environment setup, see algolia-multi-env-setup.