PostgreSQL

dev.rightsize.modules.PostgreSQLContainer — a single-node PostgreSQL container. Defaults to a test/test/test user/password/database trio so jdbcUrl is usable with zero configuration.

Defaults

Default image	postgres:18-alpine
Exposed port	5432
Env	POSTGRES_USER=test, POSTGRES_PASSWORD=test, POSTGRES_DB=test, DOCKER_PG_LLVM_DEPS="" (see below)
Wait strategy	Wait.forLogMessage(".*database system is ready to accept connections.*", times = 2)

Helpers

Member	Returns
jdbcUrl: String	A jdbc:postgresql:// URL for the running container's databaseName
username / password / databaseName: String	The configured credentials/database (default test/test/test)
withUsername(username: String): PostgreSQLContainer	Overrides POSTGRES_USER
withPassword(password: String): PostgreSQLContainer	Overrides POSTGRES_PASSWORD
withDatabase(database: String): PostgreSQLContainer	Overrides POSTGRES_DB

Call the withX overrides before start().

Example

package dev.rightsize.modules

import dev.rightsize.modules.PostgreSQLContainer
import org.junit.jupiter.api.Assertions.assertEquals
import org.junit.jupiter.api.Assertions.assertTrue
import org.junit.jupiter.api.Test
import java.sql.DriverManager

class PostgreSQLContainerTest {
    @Test
    fun `creates a table and reads it back`() {
        val postgres = PostgreSQLContainer()
        postgres.start()
        try {
            DriverManager.getConnection(postgres.jdbcUrl, postgres.username, postgres.password).use { conn ->
                conn.createStatement().use { it.execute("CREATE TABLE t (x INT)") }
                conn.createStatement().use { it.execute("INSERT INTO t (x) VALUES (1)") }
                conn.createStatement().use { st ->
                    st.executeQuery("SELECT x FROM t").use { rs ->
                        assertTrue(rs.next())
                        assertEquals(1, rs.getInt("x"))
                    }
                }
            }
        } finally {
            postgres.stop()
        }
    }
}

Backend notes

Two things that had to be figured out empirically, not guessed from the docs

Readiness needs times = 2, not times = 1. The official postgres entrypoint starts the server twice: once as a throwaway instance to run init scripts, then a second time for real — and it prints "database system is ready to accept connections" on both boots. Waiting for the first occurrence races the restart: a client can connect to the init-time instance in the brief window just before it's torn down. Waiting for the second occurrence (times = 2) waits for the real, durable listener instead.

A control-character env var crashes microsandbox outright. The official postgres:*-alpine image bakes an env var, DOCKER_PG_LLVM_DEPS, whose value contains a literal tab character (from a package list built with \t\t continuation in the Dockerfile). microsandbox 0.6.2's krun VMM panics with InvalidAscii on that value before the guest ever boots — reproduced with zero rightsize-set env vars, so this is purely an artifact of the image, not anything this library added. Docker is unaffected. This module overrides the variable to an empty string (withEnv("DOCKER_PG_LLVM_DEPS", "")), which is a no-op on Docker and the fix on microsandbox. If you hit a similar InvalidAscii panic with an image this module doesn't cover, look for a baked env var with an unusual byte in it — see Troubleshooting for the general pattern.