How to restrict connections to dockerized MongoDB from other dockerized application in the same server and deny public access to 27017

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I am using Orion Context Broker (in docker container) and I need it to connect with MongoDB (which is in its own docker container). At the same time I must deny all incoming traffic to 27017 from external sources, because after running the docker-compose the port 27017 is "exposed" to public.

All of the above using Ubuntu 20.04.

This is my docker-compose.yml file

version: "3.5"
services:
  orion:
    image: fiware/orion-ld
    hostname: orion
    container_name: fiware-orion
    expose:
      - "1026"
    ports:
      - "1026:1026"
    depends_on:
      - mongo-db
    command: -dbhost mongo-db -logLevel DEBUG

  mongo-db:
    image: mongo:3.6
    hostname: mongo-db
    container_name: db-mongo
    ports:
      - "27017:27017"
    networks:
      - default
    command: --nojournal
    volumes:
      - mongo-db:/data

volumes:
  mongo-db: ~

172.18.0.3 is the internal IP given to Orion's docker container. So I tried adding --bind_ip 172.18.0.3 to command mongo_db parameter in the docker-compose file, but this breaks the docker-compose up process with this error:

db-mongo | 2022-01-12T13:17:56.650+0000 E STORAGE [initandlisten] Failed to set up listener: SocketException: Cannot assign requested address

And this is my ubuntu firewall rules (which I just learnt that docker bypasses[*])

OpenSSH                    ALLOW       Anywhere
1026                       ALLOW       Anywhere
27017                      DENY        Anywhere
27017                      ALLOW       127.0.0.1
27017                      ALLOW       172.18.0.3
OpenSSH (v6)               ALLOW       Anywhere (v6)
1026 (v6)                  ALLOW       Anywhere (v6)
27017 (v6)                 DENY        Anywhere (v6)

[*] https://www.techrepublic.com/article/how-to-fix-the-docker-and-ufw-security-flaw/ I have also made the fix suggested by the tutorial but if restart the docker then (for some unknown reason) I stop getting access to 1026 port which should be the only public port.

fiware-orion docker-compose docker mongodb ubuntu
2 Answers

The Compose ports: setting is what makes a container accessible from outside Docker space. It's not necessary (or used) for connections between containers. Deleting this should meet your needs.

version: '3.8'
services:
  orion:
    image: fiware/orion-ld
    ports:
      - "1026:1026"  # accessible from host port 1026
    depends_on:
      - mongo-db
    command: -dbhost mongo-db -logLevel DEBUG
    #  same hostname ^^^^^^^^ and default MongoDB port 27017
# vvvvvvvv
  mongo-db:
    image: mongo:3.6
    command: --nojournal
    volumes:
      - mongo-db:/data
    # no ports:, not accessible from outside Docker

volumes:
  mongo-db:

(I've also removed unnecessary container_name:, hostname:, networks:, and expose: options from this setup; they make no difference and the Compose stack should work just fine without them.)

user_100081730

Put it on its own network (i.e. new docker network: orion_net) and only expose the ports you need. Currently you are on "default" network, which is shared.

user_41184340
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