A function to create a Postgres container with Testcontainers. Written in TypeScript.

postgresql-container.ts

import { GenericContainer, StartedTestContainer } from 'testcontainers';
import { AbstractStartedContainer } from 'testcontainers/dist/modules/abstract-started-container';
import { RandomUuid } from 'testcontainers/dist/uuid';

const POSTGRES_PORT = 5432;

export async function createDatabaseContainer() {
  // reusing the same container for all tests is considerably faster than starting a new one for each test
  const container = await new PostgreSqlContainer().withReuse().start();
  const host = container.getHost();
  const port = container.getPort();
  const database = container.getDatabase();
  const user = container.getUsername();
  const password = container.getPassword();
  // needed later to retrieve the current container, so it can be stopped and removed after the tests have run
  process.env.TEST_POSTGRES_CONTAINER_ID = container.getId();
  // the database client (e.g. Prisma) uses this to connect to the database
  process.env.POSTGRES_DATABASE_URL = `postgresql://${user}:${password}@${host}:${port}/${database}?schema=public`;
  // do anything else: e.g. run database migrations
  return container;
}

export class PostgreSqlContainer extends GenericContainer {
  private database = 'test';
  private username = new RandomUuid().nextUuid();
  private password = new RandomUuid().nextUuid();

  constructor(readonly image = 'postgres:14.2-alpine') {
    super(image);
  }

  public async start(): Promise<StartedPostgreSqlContainer> {
    this.withExposedPorts(...(this.hasExposedPorts ? this.ports : [POSTGRES_PORT]))
      .withEnv('POSTGRES_DB', this.database)
      .withEnv('POSTGRES_USER', this.username)
      .withEnv('POSTGRES_PASSWORD', this.password)
      .withStartupTimeout(120_000);
    return new StartedPostgreSqlContainer(await super.start(), this.database, this.username, this.password);
  }
}

export class StartedPostgreSqlContainer extends AbstractStartedContainer {
  private readonly port: number;

  constructor(
    readonly startedTestContainer: StartedTestContainer,
    private readonly database: string,
    private readonly username: string,
    private readonly password: string
  ) {
    super(startedTestContainer);
    this.port = startedTestContainer.getMappedPort(POSTGRES_PORT);
  }

  public getPort() {
    return this.port;
  }

  public getDatabase() {
    return this.database;
  }

  public getUsername() {
    return this.username;
  }

  public getPassword() {
    return this.password;
  }
}