glean-migration-deep-dive

# Glean Migration Deep Dive ## Overview Comprehensive guide for migrating enterprise search from Elasticsearch or Algolia to Glean. Covers connector migration (replacing custom crawlers with Glean's push indexing API), permission model changes (mapping ACLs to Glean's datasource-level permissions), and full index rebuilds using `bulkindexdocuments`. Typical timeline is 2-4 weeks for a mid-size deployment with 100K-1M documents across multiple datasources. ## Migration Assessment ```typescript // Scan current integration for deprecated patterns and index health const assessment = { source: process.env.SEARCH_PROVIDER ?? 'elasticsearch', indices: await sourceClient.cat.indices({ format: 'json' }), totalDocs: 0, connectors: [] as string[], permissionModel: '', }; for (const idx of assessment.indices) { assessment.totalDocs += parseInt(idx['docs.count'] ?? '0', 10); assessment.connectors.push(idx.index); } assessment.permissionModel = assessment.source === 'elasticsearch' ? 'index-level' : 'api-key'; console.log(`Source: ${assessment.source}`); console.log(`Indices: ${assessment.connectors.length} | Total docs: ${assessment.totalDocs}`); console.log(`Permission model: ${assessment.permissionModel} → Glean datasource ACLs`); ``` ## Step-by-Step Migration ### Phase 1: Prepare Export all documents from the current search provider and map them to Glean's document schema. Each document needs `id`, `title`, `url`, `body`, and `permissions`. ```typescript interface Gle...