Postgres adapters (@healthzkit/postgres)

The @healthzkit/postgres package provides HealthAdapter helpers for pg (node-postgres) and postgres (Postgres.js). Successful checks return ok with metadata.latencyMs plus any fields from an optional metadata hook; failures return fail with the caught error.

Install the adapter package and one database client:

pnpm add @healthzkit/postgres
# plus one of:
pnpm add pg
pnpm add postgres

pg and postgres are optional peers-install the driver you use.

Package entrypoints

• @healthzkit/postgres - pgAdapter, postgresJsAdapter, and their option types (convenient when you use both or want a single import).
• @healthzkit/postgres/pg - pgAdapter only.
• @healthzkit/postgres/postgres - postgresJsAdapter only.

Use subpath imports when you want to avoid pulling both drivers into your bundle analysis path.

Shared options

Both factories share BasePostgresOptions:

Option	Description
query	SQL string executed for the probe. Default SELECT 1.
metadata	Optional async (client) => Record<string, unknown> merged into check metadata with latencyMs.

pgAdapter (pg)

Peer: pg >= 8.

Connection string

Pass connectionString. The adapter maintains an internal Pool with max: 1, **connect()**s a client for each check, runs client.query(query), then **release()**s the client in a finally block.

import { createHealthKit } from "healthzkit";
import { pgAdapter } from "@healthzkit/postgres";

const kit = createHealthKit({
  checks: [
    {
      name: "postgres",
      type: ["readiness"],
      adapter: pgAdapter({
        connectionString: process.env.DATABASE_URL!,
        query: "SELECT 1",
      }),
    },
  ],
});

Existing client or pool

Pass client as:

• A Pool: each check calls pool.connect(), runs the query on the PoolClient, then releases it.
• A PoolClient or other ClientBase: the query runs on that instance; release is a no-op.

import { Pool } from "pg";
import { pgAdapter } from "@healthzkit/postgres/pg";

const pool = new Pool({ connectionString: process.env.DATABASE_URL! });

const adapter = pgAdapter({
  client: pool,
  query: "SELECT current_database()",
});

postgresJsAdapter (postgres)

Peer: postgres >= 3.

Connection string

Pass connectionString. The adapter dynamically imports postgres, then creates a shared sql instance with { max: 1 }.

import { postgresJsAdapter } from "@healthzkit/postgres/postgres";

const adapter = postgresJsAdapter({
  connectionString: process.env.DATABASE_URL!,
});

The check runs sql.unsafe(query) (default SELECT 1). Use only trusted query strings (your own literals or constants).

Existing client

Pass client as an existing Sql (or TransactionSql) instance from your app; no internal pool is created.

import postgres from "postgres";
import { postgresJsAdapter } from "@healthzkit/postgres";

const sql = postgres(process.env.DATABASE_URL!);

const adapter = postgresJsAdapter({
  client: sql,
  metadata: async (s) => ({ endpoint: "primary" }),
});

Scheduling

For busy databases, pair these adapters with a schedule on the check so readiness reads cached results (see Scheduling).