Jose Antonio Pio Gil

Software Engineering

Mongodb 4.2.X On Docker That Works

Programming
Databases
MongoDB
Dec 11, 2019

After troubleshooting a MongoDB 4.2.1 instance running in my local development environment I have just learnt a couple of things that may be of interest for you.

My target was to build a dockerized MongoDB server in my Elixir project and build a list of databases on it (7 indeed). Previously I was using the OS installed MongoDB version but it end up been a hassle to keep up to date with the new versions. Then I decided naively to simple pull the docker container and run it but as everything that runs with a single command... it didn't work. I let you here the steps I've follow to make it work.

Requirements

  • Docker Compose V3
  • MongoDB 4.2.x Docker container

Steps

  1. Make a Docker Compose File
  2. Make a javascript MongoDB initialization File
  3. Test your results
  4. Further help

 

Make a Docker Compose File

The general concept can be found or inferred from the official MongoDB Docker registry home page but you will to initialize each DB before by creating an user (or reusing "root" for example) and assign it the required permission to access that DB. Having this user  at the "admin" database with "root" permission didn't worked for new tables when you connect remotely to the server.


  version: '3'
  mongo:
    image: mongo
    restart: always
    command: ["--bind_ip_all"]
    environment:
      MONGO_INITDB_DATABASE: database-login-name
      MONGO_INITDB_ROOT_USERNAME: root
      MONGO_INITDB_ROOT_PASSWORD: password
    volumes:
      - ./volumes/mongo/init-mongo.js:/docker-entrypoint-initdb.d/init-mongo.js:ro
    ports:
      - '27017-27019:27017-27019'

 

Make a javascript MongoDB initialization File

This will be a vanilla javascript file that will run during the creation of the MongoDB instance. On it I just list the DBs I'll use and then create on each of them the user "root" with the "readWrite" permissions.


databases = ['any_new_database',....]

for (var i = databases.length - 1; i >= 0; i--) {
  db = db.getSiblingDB(databases[i])

  db.createUser({
    user: "root",
    pwd: "password",
    roles: ["readWrite"]
  })
}

In your MongoDB instance logs you will find something like the following output where you can see execution result from the init-mongo.js file. If you are looking for errors or the users are not created at the end then check your logs for this kind of outputs.


your-container | /usr/local/bin/docker-entrypoint.sh: running /docker-entrypoint-initdb.d/init-mongo.js
your-container | 2019-12-11T12:15:34.998+0000 I NETWORK [listener] connection accepted from 127.0.0.1:53322 #3 (1 connection now open)
your-container | 2019-12-11T12:15:34.998+0000 I NETWORK [conn3] received client metadata from 127.0.0.1:53322 conn3: { application: { name: "MongoDB Shell" }, driver: { name: "MongoDB Internal Client", version: "4.2.1" }, os: { type: "Linux", name: "Ubuntu", architecture: "x86_64", version: "18.04" } }
your-container | 2019-12-11T12:15:35.000+0000 I SHARDING [ftdc] Marking collection local.oplog.rs as collection version:
your-container | Successfully added user: { "user" : "root", "roles" : [ "readWrite" ] }

 

Test your results

Login into the container and execute mongo with you root user to test that each db has the write users.


root@5289e2d16b5a:/# mongo -u root
MongoDB shell version v4.2.1
Enter password:
connecting to: mongodb://127.0.0.1:27017/?compressors=disabled&gssapiServiceName=mongodb
Implicit session: session { "id" : UUID("44ff055f-a4dd-42bc-bf23-9b74533ffb8e") }
MongoDB server version: 4.2.1
Welcome to the MongoDB shell.
For interactive help, type "help".
For more comprehensive documentation, see
http://docs.mongodb.org/
Questions? Try the support group
http://groups.google.com/group/mongodb-user
Server has startup warnings:
2019-12-11T12:15:36.349+0000 I STORAGE [initandlisten]
2019-12-11T12:15:36.349+0000 I STORAGE [initandlisten] ** WARNING: Using the XFS filesystem is strongly recommended with the WiredTiger storage engine
2019-12-11T12:15:36.349+0000 I STORAGE [initandlisten] ** See http://dochub.mongodb.org/core/prodnotes-filesystem
---
Enable MongoDB's free cloud-based monitoring service, which will then receive and display
metrics about your deployment (disk utilization, CPU, operation statistics, etc).

The monitoring data will be available on a MongoDB website with a unique URL accessible to you
and anyone you share the URL with. MongoDB may use this information to make product
improvements and to suggest MongoDB products and deployment options to you.

To enable free monitoring, run the following command: db.enableFreeMonitoring()
To permanently disable this reminder, run the following command: db.disableFreeMonitoring()
---

 
> use your-database
switch to db
> db.getUsers()
[
  {
    "_id" : "your-database.root",
    "userId" : UUID("7989dd38-ca7e-4ffc-9af2-7e328ddb11f7"),
    "user" : "root",
    "db" : "your-database",
    "roles" : [
      {
        "role" : "readWrite",
        "db" : "your-database"
      }
    ],
    "mechanisms" : [
      "SCRAM-SHA-1",
      "SCRAM-SHA-256"
    ]
  }
]

That will be enough to make sure you will have access from remote to that database with that user. I hope this helped you in creating a working MongoDB instance with docker and let me know any feedback about this tutorial whether it worked or not for you.

 

Further help