GitHub - taktekhq/petri: Isolated, seeded database environments for parallel testing.

Drop-in replacement for postgres that gives every test its own isolated database — no cleanup, no truncation, no flaky shared state.

db:
  image: ghcr.io/taktekhq/petri-postgres:latest
  environment:
    POSTGRES_USER: appuser
    POSTGRES_PASSWORD: apppass
    POSTGRES_DB: appdb
  ports:
    - "5432:5432"   # passthrough — behaves like plain postgres
    - "5433:5433"   # fork-per-connection — each test gets its own copy

Point tests at :5433. Everything else (migrations, seeds, the app) stays on :5432.

knex({
  client: 'pg',
  connection: { host: 'db', port: 5433, ... },
  pool: { min: 1, max: 1 },   // one connection = one fork — required
})

Migrations

Run against :5432. Writes land on the template; every fork inherits them.

Examples

examples/bun-knex — before/after with Bun + Knex. Shows what breaks without isolation and what passes with it.

examples/fastapi-pytest — before/after with FastAPI + pytest. Same pattern in Python.

How it works

See HOWITWORKS.md.