MongoDB In-Memory Server

This package spins up an actual/real MongoDB server programmatically from within nodejs, for testing or mocking during development. By default it holds the data in memory. A fresh spun up mongod process takes about 7Mb of memory. The server will allow you to connect your favorite ODM or client library to the MongoDB server and run integration tests isolated from each other.

On install, this package downloads the latest MongoDB binaries and saves them to a cache folder. (only mongodb-memory-server-core does not download on postinstall)

On starting a new instance of the memory server, if the binary cannot be found, it will be auto-downloaded (if RUNTIME_DOWNLOAD option is truthy), thus the first run may take some time. All further runs will be fast, because they will use the downloaded binaries.

This package automatically downloads binaries from https://fastdl.mongodb.org/ according to your operating system. You can see all available versions for Linux (Ubuntu, RHEL, Debian, SUSE, Amazon), OSX, and Windows.

If your network is behind a proxy, make sure that it is configured through the HTTPS_PROXY or HTTP_PROXY environment variable.

Every MongoMemoryServer instance creates and starts a fresh MongoDB server on some free port. You may start up several mongod simultaneously. When you terminate your script or call stop(), the MongoDB server(s) will be automatically shutdown.

Works perfectly with any CI runner that can run NodeJS applications.

Table of Contents generated with DocToc

• Installation
  • Requirements
  • Choose the Correct Package
  • Configuring which mongod binary to use
• Usage
  • Simple server start
  • Available options for MongoMemoryServer
  • Replica Set start
  • Available options for MongoMemoryReplSet
  • Config Options
  • Simple test with MongoClient in Jest
  • Provide connection string to mongoose
  • Test Runner Examples
  • Docker Alpine
  • Enable Debug Mode
• Contributing
• Join Our Discord Server
• Documentation
• Credits
  • Inspired by
  • Maintainers
• Funding
  • Contributors
  • Backers
  • Sponsors
• License

Installation

This tool provides three packages for different purposes:

• With auto-download mongod binary on npm install (mongodb-memory-server, mongodb-memory-server-global-*)
• Without auto-download on npm install (mongodb-memory-server-core)

Choose any package, because they are the same. They differ only in the default configuration, which you may override (see section Available options).

Requirements

• NodeJS: 16.20.1+
• Typescript: 5.3+ (if used)

And one of those (on Linux):

• having lsb-core installed (or any that provides the lsb_release command)
• having an /etc/os-release file that is compliant to the OS-Release Spec
• having an /etc/*-release file that is compliant to the OS-Release Spec (and does not include lsb)
• manually specify which version & system should be used

On Linux, you will also need libcurl4 (or libcurl3 on some older distro versions). This will probably only be an issue on "slim" Docker images.

Choose the Correct Package

Choose the right package for the task

Configuring which mongod binary to use

The default behavior is that version 7.0.14 for your OS will be downloaded. By setting Environment variables you are able to specify which version and binary will be downloaded:

1export MONGOMS_DOWNLOAD_URL=https://fastdl.mongodb.org/linux/mongodb-linux-x86_64-ubuntu1804-4.2.8.tgz
2export MONGOMS_VERSION=4.2.8

Usage

Simple server start

A Normal Server can be easily started with:

1import { MongoMemoryServer } from 'mongodb-memory-server';
2
3// This will create an new instance of "MongoMemoryServer" and automatically start it
4const mongod = await MongoMemoryServer.create();
5
6const uri = mongod.getUri();
7
8// The Server can be stopped again with
9await mongod.stop();

Available options for MongoMemoryServer

All options with ? are optional, some options upon specified are required.

1const mongod = new MongoMemoryServer({
2  instance?: {
3    port?: number, // by default choose any free port
4    ip?: string, // by default '127.0.0.1', for binding to all IP addresses set it to `::,0.0.0.0`,
5    dbName?: string, // by default '' (empty string)
6    dbPath?: string, // by default create in temp directory
7    storageEngine?: string, // by default `ephemeralForTest`(unless mongodb 7.0.0, where its `wiredTiger`), available engines: [ 'ephemeralForTest', 'wiredTiger' ]
8    replSet?: string, // by default no replica set, replica set name
9    args?: string[], // by default no additional arguments, any additional command line arguments for `mongod` `mongod` (ex. ['--notablescan'])
10    auth?: boolean, // add "--auth" argument, dont use this directly use top-level "auth"
11  },
12  binary?: {
13    version?: string, // by default '7.0.14'
14    downloadDir?: string, // see the documentation on what is chosen by default https://typegoose.github.io/mongodb-memory-server/docs/api/config-options#download_dir
15    platform?: string, // by default os.platform()
16    arch?: string, // by default os.arch()
17    checkMD5?: boolean, // by default false OR process.env.MONGOMS_MD5_CHECK
18    systemBinary?: string, // by default undefined or process.env.MONGOMS_SYSTEM_BINARY
19  },
20  // using "auth" will manage "instance.auth"
21  auth?: {
22    // enable needs to be set to "true", otherwise automatic user creation is by default disabled
23    enable?: boolean, // enable automatic user creation
24    customRootName?: string, // by default "mongodb-memory-server-root"
25    customRootPwd?: string, // by default "rootuser"
26    force?: boolean, // force creation of users
27    keyfileContent?: string, // by default "0123456789" (only useful for replsets)
28    extraUsers?: [{
29      // see mongodb documentation https://docs.mongodb.com/manual/reference/method/db.createUser/#definition)
30      createUser: string, // user name
31      pwd: string, // user password
32      roles: UserRoles[], // user roles
33      database?: string, // which database the user is created on
34      customData?: Record<string, any>, // any arbitrary information, see mongodb documentation
35      mechanisms?: ('SCRAM-SHA-1' | 'SCRAM-SHA-256')[],
36      authenticationRestrictions?: {
37        clientSource?: string;
38        serverAddress?: string;
39      }[],
40      digestPassword?: boolean,
41    }],
42  },
43});

Replica Set start

A ReplicaSet can be easily started with:

1import { MongoMemoryReplSet } from 'mongodb-memory-server';
2
3// This will create an new instance of "MongoMemoryReplSet" and automatically start all Servers
4const replset = await MongoMemoryReplSet.create({ replSet: { count: 4 } }); // This will create an ReplSet with 4 members
5
6const uri = replset.getUri();
7
8// The ReplSet can be stopped again with
9await replset.stop();

Available options for MongoMemoryReplSet

All options are optional.

1const replSet = new MongoMemoryReplSet({
2  binary: binaryOpts, // same as for MongoMemoryServer
3  instanceOpts: [
4    {
5      args, // any additional instance specific args
6      port, // port number for the instance
7      dbPath, // path to database files for this instance
8      storageEngine, // same storage engine options
9    },
10    // each entry will result in a MongoMemoryServer (replSet.count will not limit the amount spawned by "instanceOpts")
11  ],
12  // unless otherwise noted below these values will be in common with all instances spawned:
13  replSet: {
14    name, // replica set name (default: 'testset')
15    auth?: boolean | AutomaticAuth, // enable auth, for options see #available-options-for-mongomemoryserver
16    args, // any args specified here will be combined with any per instance args from `instanceOpts`
17    count, // number of additional `mongod` processes to start (will not start any extra if instanceOpts.length > replSet.count); (default: 1)
18    dbName, // default database for db URI strings
19    ip, // by default '127.0.0.1', for binding to all IP addresses set it to `::,0.0.0.0`
20    spawn, // spawn options when creating the child processes
21    storageEngine, // default storage engine for instance. (Can be overridden per instance)
22    configSettings: {
23      // Optional settings for 'replSetInitiate' command. See https://docs.mongodb.com/manual/reference/command/replSetInitiate/
24      chainingAllowed: boolean, // When true it allows secondary members to replicate from other secondary members. When false, secondaries can replicate only from the primary.
25      heartbeatTimeoutSecs: number, // Number of seconds that the replica set members wait for a successful heartbeat from each other. If a member does not respond in time, other members mark the delinquent member as inaccessible.
26      heartbeatIntervalMillis: number, // The frequency in milliseconds of the heartbeats.
27      electionTimeoutMillis: number, // The time limit in milliseconds for detecting when a replica set’s primary is unreachable.
28      catchUpTimeoutMillis: number, // Time limit for a newly elected primary to sync (catch up) with the other replica set members that may have more recent writes.
29    },
30  },
31});

Config Options

Documentation of Config Options

Simple test with MongoClient in Jest

A example test file for a single MongoMemoryServer within jest.

A example test file for multiple MongoMemoryServer within jest.

A example test file for a single MongoMemoryReplSet within jest.

Provide connection string to mongoose

1// assuming mongoose@6.x
2import mongoose from 'mongoose';
3import { MongoMemoryServer } from 'mongodb-memory-server';
4
5const mongoServer = await MongoMemoryServer.create();
6
7(async () => {
8  await mongoose.connect(mongoServer.getUri(), { dbName: "verifyMASTER" });
9
10  // your code here
11  
12  await mongoose.disconnect();
13})();

Test Runner Examples

Documentation for Test Runner Integration Examples

Docker Alpine

There isn't currently an official MongoDB release for alpine linux. This means that we can't pull binaries for Alpine (or any other platform that isn't officially supported by MongoDB), but you can use a Docker image that already has mongod built in and then set the MONGOMS_SYSTEM_BINARY variable to point at that binary. This should allow you to use mongodb-memory-server on any system on which you can install mongod manually.

Enable Debug Mode

The Debug mode can be enabled with an Environment-Variable or in the package.json "config" section:

1MONGOMS_DEBUG=1 # also available case-insensitive values: "on" "yes" "true"

or

1{
2  "config": {
3    "mongodbMemoryServer": {
4      "debug": "1" // also available case-insensitive values: "on" "yes" "true"
5    }
6  }
7}

Also see the Enable Debug Mode Guide.

Contributing

Contributing Guidelines are setup in CONTRIBUTING

Join Our Discord Server

To ask questions or just talk with us, join our Discord Server.

Documentation

• Documentation
• Quick start guide
• Known Issues

Credits

Inspired by

Inspired by alternative runners for mongodb-prebuilt:

• mockgoose
• mongomem

Maintainers

• @nodkz Pavel Chertorogov
• @AJRdev Andre Ranarivelo
• @hasezoey

Funding

Contributors

This project exists thanks to all the people who contribute.

Backers

Thank you to all our backers! 🙏 [Become a backer]

Sponsors

Support this project by becoming a sponsor. Your logo will show up here with a link to your website. [Become a sponsor]

License

MIT