Connect TypeScript to Azure PostgreSQL

Connects to Azure Database for PostgreSQL Flexible Server from TypeScript using the pg (node-postgres) package, supporting both password and Microsoft Entra ID passwordless authentication.

npm install pg @azure/identity
npm install -D @types/pg

Password auth reads AZURE_POSTGRESQL_HOST/DATABASE/PORT/USER/PASSWORD and creates a Client with ssl: { rejectUnauthorized: true } (required for Azure). Entra ID auth (recommended) instead acquires an access token via DefaultAzureCredential().getToken("https://ossrdbms-aad.database.windows.net/.default") and passes the token as the password, supporting both system-assigned and user-assigned managed identity (the latter via managedIdentityClientId); a documented AzurePostgresPool wrapper class refreshes the token 5 minutes before its roughly 1-hour expiry and rebuilds the pool.

Core workflows: a single Client connection closed with client.end() in a finally block; a connection Pool (recommended for production, configured with max, idleTimeoutMillis, and connectionTimeoutMillis) either queried directly or checked out with pool.connect()/client.release() for multiple queries; parameterized queries ($1, $2, ...) to prevent SQL injection, including array parameters via = ANY($1::int[]); transactions wrapped in BEGIN/COMMIT/ROLLBACK with a reusable withTransaction<T> helper; and typed queries using pool.query<User>(...) with a QueryResult<User> return type. Error handling switches on Postgres error codes: 23505 unique_violation, 23503 foreign_key_violation, 42P01 undefined_table, 28P01 invalid_password, and 57P03 cannot_connect_now. An alternative connection-string form appends ?sslmode=require, and Pool emits connect/acquire/release/remove/error events, with pool.totalCount, pool.idleCount, and pool.waitingCount recommended for monitoring pool health. Stated best practices: always use connection pools in production, always parameterize queries rather than concatenating input, always close connections via try/finally or the pool, enable SSL, handle Entra ID token refresh, set connection timeouts, wrap multi-statement operations in transactions, monitor pool metrics, shut down gracefully with pool.end(), and type query results with TypeScript generics.

Use it to connect a TypeScript/Node application to Azure Database for PostgreSQL Flexible Server with either password or Entra ID authentication, run pooled or single-client queries, or handle Azure-specific SSL and token-refresh requirements.

Azure-specific reference values: SSL rejectUnauthorized: true is always required, default port 5432 (6432 with PgBouncer enabled), Entra ID token scope https://ossrdbms-aad.database.windows.net/.default, and roughly 1-hour token lifetime requiring refresh before expiry. Pool-sizing guidance: 5-10 connections for light/dev workloads, 20-30 for medium production, 50-100 for heavy concurrency, bounded by Azure's own per-SKU connection limits. Key exported types: Client, Pool, PoolClient, PoolConfig, QueryResult, QueryResultRow, DatabaseError, QueryConfig.

Built on the pg (node-postgres) package and @azure/identity's DefaultAzureCredential for token acquisition; references node-postgres documentation, the pg npm package and GitHub repository, and Microsoft's Azure PostgreSQL and passwordless-connection docs.

TypeScript/Node developers connecting to Azure Database for PostgreSQL who need production-ready patterns for pooling, parameterized queries, transactions, typed results, and Entra ID token refresh rather than a bare connection snippet.