CODEWITHSUNDEEP
docker
Guerrilla
Guerrilla

Reputation: 14846

How to network multiple stacks in swarm

I have multiple stacks running in my swarm. The stacks are created from compose files. For illustrative purposes let's say I have the following:

Stack 1
  - Nginx container
  
Stack 2
  - Web App Container
  - Database Container
  - Cache Container
  - SMTP Container
  
Stack 3 
  - Web App Container
  - Database Container

When I deploy these stacks docker creates an overlay network so I have 3 independent overlay networks for each stack.

What I would like to do is make it so the Web App Container in Stack 2 & 3 have access to the Stack 1 overlay network so that I can proxy_pass incoming connections without having to expose the port to the internet.

The docker website only seems to have an explanation for the legacy swarm networking: https://docs.docker.com/compose/networking/

That page says for stacks networking to refer to this page: https://docs.docker.com/engine/reference/commandline/stack_deploy/

I cannot see any information about networking on that page so i am a bit stuck.

Inside the web app service definition I have tried adding:

networks:
 - nginx_default

This is the network name as shown by running docker network ls but I get an error message that this network is not defined.

What is the right way to get my web app containers and my nginx container on the same private network?

Upvotes: 1

Views: 1235

Answers (1)

Guerrilla
Guerrilla

Reputation: 14846

My issue was I needed to declare the network as external. Here is working sample config for stack 2:

version: "3.8"
networks:
  stack2:
  nginx:
    external: true
services:
    db:
        networks:
            stack2:
        image: mysql:5.7
    webapp:
        networks:
            stack2:
            nginx:
        image: webapp

This will connect webapp to the nginx network but the database wont be exposed to it.

Upvotes: 2

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