MySQL Memory Server

This package allows you to create ephemeral MySQL databases from JavaScript and/or TypeScript code and also the CLI, great for testing, CI, and learning MySQL. When creating a new database, if the version selected is not installed on the system, the binary is downloaded from MySQL's CDN (cdn.mysql.com)

You can run multiple MySQL databases with this package at the same time. Each database will use a random free port. The databases will automatically shutdown when the JS runtime process exits. A stop() method is also provided to stop each database instance.

Installation

Download with your package manager of choice. The package name is mysql-memory-server. If using npm, the install command will be npm install mysql-memory-server.

Requirements

• Node.js >=16.6.0 or Bun >= 1.0.0
• macOS 13+, Windows, or Linux (This package is only tested on Ubuntu 20.04, 22.04, 24.04, and Fedora 40. Other Linux distributions may or may not work at this time.)

Requirements for downloaded MySQL versions

The following requirements only apply if you intend to have mysql-memory-server download a version of MySQL to use instead of using an already installed version of MySQL on the system:

Requirements for Windows:

• Microsoft Visual C++ 2019 Redistributable Package needs to be installed

Requirements for Linux:

• The libaio1 or libaio1t64 package needs to be installed
• If libaio1 is not available but libaio1t64 is, the ldconfig command needs to be available to run
• The tar package needs to be installed

Currently supported MySQL versions

• If using the system installed MySQL server: 8.0.20 and newer
• If not using the system installed MySQL server: 8.0.39, 8.0.40, 8.1.0, 8.2.0, 8.3.0, 8.4.2, 8.4.3, 9.0.1, 9.1.0

Example Usage - Application Code

This package supports both ESM and CJS so you can use import or require.

import { createDB } from 'mysql-memory-server';
import sql from 'mysql2/promise'

// Create a new database with default options
const db = await createDB()

//OR

//Create a new database with custom options set
const db = await createDB({
        // see Options below for the options you can use in this object and their default values
        // for example:
        version: '8.4.x'
})

// Connect to the new database with the port provided
// The database is initialized with an empty password so use an empty string for the password
const connection = await sql.createConnection({
        host: '127.0.0.1',
        user: db.username,
        port: db.port,
        database: db.dbName,
        password: ''
})

// Run your queries here
// ...

// Once done, disconnect from the database
await connection.end()

// Then stop the database
await db.stop()

MySQL database initialization can take some time. If you run into a "Timeout exceeded" error with your tests, the timeout should be extended. If using Jest, information about how to do this can be found here: https://jestjs.io/docs/jest-object#jestsettimeouttimeout

Example Usage - CLI

# Options are added by doing --{optionName} {optionValue}
# See Options below for the options you can use with this package
npx mysql-memory-server@latest --version 8.4.x

Documentation

createDB(options: ServerOptions): Promise<MySQLDB>

On success, resolves with an object with the following properties:

• port: number The port that the MySQL database is listening on
• xPort: number The port that MySQLX is listening on
• dbName: string The database that was created on database initialization
• username: string The name of the user to use to login to the database
• socket: string If on Windows, this is the name of the named pipe that MySQL is listening on. If not on Windows, this is the path to the socket that MySQL is listening on.
• xSocket: string If on Windows, this is the name of the named pipe that the MySQL X Plugin is listening on. If not on Windows, this is the path that the MySQL X Plugin is listening on.
• mysql: {version: string, versionIsInstalledOnSystem: boolean} An object with two properties. version is the version of MySQL used to create the database. versionIsInstalledOnSystem will be true if the MySQL version used is already installed on the system and false if the version had to be downloaded from MySQL's CDN.
• stop: () => Promise<void> The method to stop the database. The returned promise resolves when the database has successfully stopped.

Options:

All options are not required to be set. Using undefined as a value will use the option's default value.

• version: string

Default: undefined

Description: Version of MySQL to use for the database. Uses semver for getting the version, so valid semver versions are allowed. For example, 8.x is a valid version and will use the latest 8.x MySQL version.

If left undefined:

• If the system has MySQL installed, the system-installed version will be used. If the installed version is not supported by this package (currently <8.0.20), an error will be thrown unless ignoreUnsupportedSystemVersion is set to true.
• If the system does not have MySQL installed, the latest version of MySQL in the versions.json file in this package will be downloaded.

If defined:

• If the version is 8.0.19 or older, an error will be thrown as this package does not currently support those versions of MySQL.

• If the desired version of MySQL is installed on the system, the installed version will be used. Otherwise the selected version will be downloaded from the MySQL CDN as long as it can be found in the versions.json file. If it cannot be found in that file, an error will be thrown.

• dbName: string

Default: "dbdata"

Description: The name of the database to create when initializing MySQL. You'd use this name to connect to the database.

• logLevel: "LOG" | "WARN" | "ERROR"

Default: "ERROR"

Description: Log level for this package. If "ERROR" is used, only errors from this package will show up in the console. If "WARN" is used, warnings and errors from this package will show up in the console. If "LOG" is used, every log from this package will show up in the console.

• portRetries: number

Default: 10

Description: Number of times to try connecting MySQL to a randomly generated port before giving up. According to the MySQL Documentation if port 0 is used as the MySQL server port, the default value (3306) will be used. To get around this, a random number between 1025 - 65535 (inclusive) is generated and used for the database's port. If MySQL cannot successfully listen on a randomly generated port after portRetries then the createDB() promise is rejected. A warning is created when MySQL tries connecting to a port that is already in use. This option only applies for the MySQL port if the MySQL port is not explicitly set or if it's set to 0. This option also only applies for the MySQL X port if the MySQL X port is not explicitly set or if it's set to 0.

• downloadBinaryOnce: boolean

Default: true

Description: If set to true, all versions requested that need to be downloaded from MySQL's CDN will be downloaded once and will stay on the system after the database stops. If set to false, the binaries that need to be downloaded will be downloaded for each database creation and will be deleted when the database is stopped.

Use false to save disk space after the databases have been stopped, or use true to save bandwidth

• lockRetries: number

Default: 1,000

Description: If downloadBinaryOnce is set to true, lockRetries is the number of times to check to see if the lock for the binary has been released (meaning it has been successfully downloaded and extracted). If the number of retries exceeds lockRetries, the createDB() promise gets rejected. This option is also used for the number of times to check to see if the lock for libaio has been released (only on Linux distros that use libaio1t64 instead of libaio1)

• lockRetryWait: number

Default: 1,000

Description: If downloadBinaryOnce is set to true and/or on Linux distros that use libaio1t64 instead of libaio1, lockRetryWait is the number of milliseconds to wait before checking if the lock has been released.

• username: string

Default: root

Description: The username of the user that is used to login to the database.

• port: number

Default: 0

Description: The port that the database will listen on. If set to 0, a randomly generated port is used.

• xPort: number

Default: 0

Description: The port that the MySQL X Plugin will listen on. If set to 0, a randomly generated port is used.

• ignoreUnsupportedSystemVersion: boolean

Default: false

Description: This option only applies if the system-installed MySQL version is lower than the oldest supported MySQL version for this package (8.0.20) and the version option is not defined. If set to true, this package will use the latest version of MySQL instead of the system-installed version. If false, the package will throw an error.

• downloadRetries: number

Default: 3

Description: The number of times to try to download a MySQL binary before giving up and rejecting the createDB() promise.

• initSQLString: string

Default: ""

Description: A string with MySQL queries to run before the database starts to accept connections. This option can be used for things like initialising tables without having to first connect to the database to do that. The queries in the string get executed after mysql-memory-server's queries run. Uses the --init-file MySQL server option under the hood. Learn more at the --init-file MySQL Documentation

The internal queries that are ran before the queries in initSQLString are renaming the user from root to the username specified in the username option if it's set, and creating a database with the name from the dbName option.

• arch: "arm64" | "x64"

Default: process.arch

Description: The MySQL binary architecture to execute. MySQL does not offer server builds for Windows on ARM, so to get this package working on Windows on ARM, set the arch option to "x64" and Windows will emulate MySQL.

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⚠️ Internal Options ⚠️

The following options are only meant for internal use (such as for testing this package or the internals for running this package via the CLI). Their behaviour may change or they may get removed between major/minor/patch versions and they are not to be considered stable. The options below will not follow Semantic Versioning so it is advised to not use them.

• _DO_NOT_USE_deleteDBAfterStopped: boolean

Default: true

Description: Changes whether or not the database will be deleted after it has been stopped. If set to true, the database WILL be deleted after it has been stopped.

• _DO_NOT_USE_dbPath: string

Default: TMPDIR/mysqlmsn/dbs/UUID (replacing TMPDIR with the OS temp directory and UUID with a UUIDv4 without seperating dashes).

Description: The folder to store database-related data in

• _DO_NOT_USE_binaryDirectoryPath: string

Default: TMPDIR/mysqlmsn/binaries (replacing TMPDIR with the OS temp directory)

Description: The folder to store the MySQL binaries when they are downloaded from the CDN.

• _DO_NOT_USE_cli: boolean

Default: false if the package is not being executed via the CLI and true if it is.

Description: If set to true, this enables certain CLI-only functionality. For example, when ran by the CLI, logging a message to the console when a shutdown signal (like CTRL + C) has been received and the MySQL database is shutting down and getting deleted.