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: floats to mysql:latest — this module previously pinned mysql:8.4. Guest port: 3306 Expected repository: mysql

Compatibility checking

with_image takes impl Into<ImageName> and keeps the image verbatim. start() then checks that image’s repository (registry host, tag, and digest stripped) against mysql before any backend is resolved or any sandbox is created, which keeps the constructors infallible like every other module’s. A mismatch returns RightsizeError::IncompatibleImage; ImageName::parse(image) .as_compatible_substitute_for("mysql") is the escape hatch for a verified drop-in replacement from another registry. new() goes through this same check against its own floating reference, so it can never fail in practice.

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.