How to store MongoDB data with docker-compose

Question

I have this docker-compose:

version: "2"
services:
  api:
    build: .
    ports:
      - "3007:3007"
    links:
      - mongo
  mongo:
    image: mongo
    volumes:
      - /data/mongodb/db:/data/db
    ports:
      - "27017:27017"

The volumes, /data/mongodb/db:/data/db, is the first part (/data/mongodb/db) where the data is stored inside the image and the second part (/data/db) where it's stored locally?

It works on production (ubuntu) but when i run it on my dev-machine (mac) I get:

ERROR: for mongo  Cannot start service mongo: error while creating mount source path '/data/mongodb/db': mkdir /data/mongodb: permission denied

Even if I run it as sudo. I've added the /data directory in the "File Sharing"-section in the docker-program on the mac.

Is the idea to use the same docker-compose on both production and development? How do I solve this issue?

Answer 1

Actually it's the other way around (HOST:CONTAINER), /data/mongodb/db is on your host machine and /data/db is in the container.

You have added the /data in the shared folders of your dev machine but you haven't created /data/mongodb/db, that's why you get a permission denied error. Docker doesn't have the rights to create folders.

Answer 2

I get the impression you need to learn a little bit more about the fundamentals of Docker to fully understand what you are doing. There are a lot of potential pitfalls running Docker in production, and my recommendation is to learn the basics really well so you know how to handle them.

Here is what the documentation says about volumes:

[...] specify a path on the host machine (HOST:CONTAINER)

So you have it the wrong way around. The first part is the past on the host, e.g. your local machine, and the second is where the volume is mounted within the container.

Regarding your last question, have a look at this article: Using Compose in production.