MySqlContainer

A single-node MySQL container. Defaults to a test/test/test user/password/database trio (plus MYSQL_ROOT_PASSWORD=test) so connection_string() is usable with zero configuration.

Default image: mysql:8.4 Guest port: 3306

Readiness — empirically pinned, not guessed

The official entrypoint boots mysqld twice: once as a throwaway “temp server” to run init scripts, then for real. Both prints, plus the X Plugin’s own “ready for connections” line, contain the substring ready for connections, and naively counting occurrences is a trap: the temp server’s X Plugin binds port: 33060 — whose digits start with 3306, so an unanchored port: 3306 search false-matches it too.

Captured verbatim from a real docker run mysql:8.4 boot with this module’s env (MYSQL_USER=test, MYSQL_DATABASE=test, MYSQL_ROOT_PASSWORD=test):

[System] [MY-011323] [Server] X Plugin ready for connections. Socket: /var/run/mysqld/mysqlx.sock
[System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.4.10'  socket: '/var/run/mysqld/mysqld.sock'  port: 0  MySQL Community Server - GPL.
...(init scripts run, temp server shuts down)...
[System] [MY-011323] [Server] X Plugin ready for connections. Bind-address: '::' port: 33060, socket: /var/run/mysqld/mysqlx.sock
[System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.4.10'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  MySQL Community Server - GPL.

Four lines contain ready for connections; only the last is the real server bound to 3306. The temp server prints port: 0 (no port yet) and the X Plugin lines print 33060, whose 3306 prefix would satisfy an unanchored match. This module ships a small custom WaitStrategy (predating Wait::for_log_message’s move to a real regex engine — see Wait Strategies) rather than a regex: it requires a line to contain mysqld: ready for connections, then checks that port: 3306 appears later on that same line immediately followed by end-of-line or a non-digit — which is exactly what rules out 33060. This is equivalent to a regex anchor, port: 3306($|[^0-9]); the hand-written character check is untouched by the regex-engine swap, since it was never built on the shared matcher in the first place.

Complete example

use mysql_async::prelude::*;
use rightsize_modules::MySqlContainer;

#[tokio::test]
async fn mysql_round_trips_a_row() -> Result<(), Box<dyn std::error::Error>> {
    let guard = MySqlContainer::new().start().await?;

    let pool = mysql_async::Pool::new(guard.connection_string().as_str());
    let mut conn = pool.get_conn().await?;

    conn.query_drop("CREATE TABLE smoke (id INT PRIMARY KEY, note TEXT)").await?;
    conn.exec_drop(
        "INSERT INTO smoke (id, note) VALUES (?, ?)",
        (1i32, "hello-rightsize"),
    ).await?;
    let note: Option<String> = conn
        .exec_first("SELECT note FROM smoke WHERE id = ?", (1i32,))
        .await?;
    assert_eq!(note.as_deref(), Some("hello-rightsize"));

    drop(conn);
    pool.disconnect().await.ok();
    guard.stop().await?;
    Ok(())
}

Backend notes

No memory-limit override: MySQL 8.4’s InnoDB default footprint fits msb’s default ~450 MB microVM RAM, unlike SpringCloudConfigContainer’s Paketo JVM image — no module-level memory floor was warranted here after measurement.